73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: enaberif on May 15, 2015, 09:11:45 PM
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Trying to figure out if this fan would work on my truck? 74 chev with a sbc 350.
(http://i.imgur.com/qDmN3PV.jpg)
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maybe it's the angle of the photo...but it looks like that fan is either missing a blade or has been the victim of an impact of some sort.
remove the fan clutch and we can tell you if the bolt pattern is correct.
Long or short water pump?
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Some fan have the blades spaced oddly to make it quieter. If they were all equal, it would sound like an airplane.
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This post just made me chuckle...made me think of something I made jokes about quite often years ago, back when just about every car you worked on had a mechanical fan. I'm convinced (not really, just part of the rant) that a young guy started in 1950 with GM in the "Cooling Division" & after a few days on the job...looking at this basic cross 4 blade fan he thought: "How am I ever going to make it to retirement here?" To keep his job, he set out to make "new" fans...curved blades, folded blades. Later 3 blades (in the early Astro vans) MANY 5 & 6 blades, even some of those big Buicks & Caddy's in the '70's had 7 & maybe even 8! more curved blades, big spaces, no spaces (7 blades!) 14", 14 1/2" 16" 18"...this clutch, that clutch & so on.
He retired around 1990 & they said: "Now what are we going to do? Fred the fan man is Gone! Some electrical wiz kid stood up & said: I'll take that department over" ...the rest is history!
Seriously, I'd love to spend a bunch of time with a pile of fans on a dyno & air flow readings (which is what GM did) to see what amount of difference some of them made...I bet MANY of them are so close it really wasn't worth the bother, however they needed .2 MPG or something to get where they needed to be. Lorne
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This post just made me chuckle...made me think of something I made jokes about quite often years ago, back when just about every car you worked on had a mechanical fan. I'm convinced (not really, just part of the rant) that a young guy started in 1950 with GM in the "Cooling Division" & after a few days on the job...looking at this basic cross 4 blade fan he thought: "How am I ever going to make it to retirement here?" To keep his job, he set out to make "new" fans...curved blades, folded blades. Later 3 blades (in the early Astro vans) MANY 5 & 6 blades, even some of those big Buicks & Caddy's in the '70's had 7 & maybe even 8! more curved blades, big spaces, no spaces (7 blades!) 14", 14 1/2" 16" 18"...this clutch, that clutch & so on.
He retired around 1990 & they said: "Now what are we going to do? Fred the fan man is Gone! Some electrical wiz kid stood up & said: I'll take that department over" ...the rest is history!
Seriously, I'd love to spend a bunch of time with a pile of fans on a dyno & air flow readings (which is what GM did) to see what amount of difference some of them made...I bet MANY of them are so close it really wasn't worth the bother, however they needed .2 MPG or something to get where they needed to be. Lorne
::) Laughing my rear end off.....so true!
LTZ C20
Thank you for the insight....I had no idea. Come to think of it, mine does sound like an airplane.....but the stroked block, my particular cam, headers, and exhaust are so loud no one would readily notice ;D
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Your welcome, if I remember correctly, my original fan had 6 or 7 blades, and they were spaced so that the space between blade 1 & 2 was 1 inch, 2 & 3 was 1 1/2, 3 & 4 was 2 inch, etc etc. Not exact measurements but at the end, the space between blades 6 or 7 & 1 was the biggest.
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That looks exactly like the fan on my '75 350 K10 (minus the crusty stuff).
Off Topic:
Times were good for Harold the high beam switch guy too.
Harold was responsible for the same floor mounted high beam switch for decades making only minor changes during his long and illustrious career.
Then came Steve the steering column guy who one day proclaimed “I can move Harold's high beam switch from the grungy floor to my new super awesome turn signal stalk”.
Sadly, Harold retired a broken man however Steve continues to pack more stuff into his turn signal stalk than Harold could have ever imagined. Just ask Wilbur the wiper switch guy, Christopher the cruise control guy, and Horatio the headlamp switch guy.
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That looks exactly like the fan on my '75 350 K10 (minus the crusty stuff).
Off Topic:
Times were good for Harold the high beam switch guy too.
Harold was responsible for the same floor mounted high beam switch for decades making only minor changes during his long and illustrious career.
Then came Steve the steering column guy who one day proclaimed “I can move Harold's high beam switch from the grungy floor to my new super awesome turn signal stalk”.
Sadly, Harold retired a broken man however Steve continues to pack more stuff into his turn signal stalk than Harold could have ever imagined. Just ask Wilbur the wiper switch guy, Christopher the cruise control guy, and Horatio the headlamp switch guy.
LMBO!!! You did forget tho, at first they did not have alot of faith in Steve because the steering column switches kept breaking at the base when they were the fully plastic deaign. Also, Wilbur got a big raise a couple years ago when he figured out the "rain sense" automatic wipers.
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That looks exactly like the fan on my '75 350 K10 (minus the crusty stuff).
Off Topic:
Times were good for Harold the high beam switch guy too.
Harold was responsible for the same floor mounted high beam switch for decades making only minor changes during his long and illustrious career.
Then came Steve the steering column guy who one day proclaimed “I can move Harold's high beam switch from the grungy floor to my new super awesome turn signal stalk”.
Sadly, Harold retired a broken man however Steve continues to pack more stuff into his turn signal stalk than Harold could have ever imagined. Just ask Wilbur the wiper switch guy, Christopher the cruise control guy, and Horatio the headlamp switch guy.
I love it! Oh, the stuff we think of to make it through the day! Wouldn't you love to spend some time as a fly on the wall in some of these engineering rooms? Thank You for the laugh...even got the new headlight switch guy's name "correct"! Lorne
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Well that is the thing. I don't know if the original fixed fan is what should be on the truck. And the fan I got is similar to the one I posted. I know the fan blades are opposite to one another and I had to take off the fixed fan because it was over cooling my truck. I've tried to find pics of trucks of the 73-80 era with clutch fans but they don't seem to exist and I can't find any around where I am.
Also I've learned that any truck that uses serpentine is reverse rotation and the same thing applies to the clutch.
Said fixed fan.
(http://i.imgur.com/gKLVStc.jpg)
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Well that is the thing. I don't know if the original fixed fan is what should be on the truck. And the fan I got is similar to the one I posted. I know the fan blades are opposite to one another and I had to take off the fixed fan because it was over cooling my truck. I've tried to find pics of trucks of the 73-80 era with clutch fans but they don't seem to exist and I can't find any around where I am.
Also I've learned that any truck that uses serpentine is reverse rotation and the same thing applies to the clutch.
Said fixed fan.
Over cooling? ??? hardly seems possible. What is the degree rating of your thermostat?
The direction of the blades indicates the direction of rotation. A standard long water pump will rotate clockwise. Your fan clutch needs to match the rotation of your fan (clockwise or counterclockwise).
It is not true that "any truck that uses serpentine is reverse rotation." GM performance serpentines do use a reverse rotation water pump....and therefore requires a counterclockwise fan and fan clutch. But there are many, many aftermarket serpentine systems. Several companies make serpentine systems that utilize the standard long or short water pump and do not require a reverse in direction.
This whole fan situation is really the most untrivial part your drivetrain....albeit important. The fan bolts up to your water pump pulley with four nuts or bolt. Just put the fan on, start your truck, and determine which way the air is moving.....if the air is being pulled through the rad, then you're good. If the air is being pushed through your rad, then you need a fan that runs in the other direction. Don't worry about the fan clutch for now.....once you know the direction then you'll know if the clutch works for your application or not.
Note: you can't just take a fan and turn it over to make it work in the opposite direction.
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Yes over cooling. With that fixed fan on my truck I could not get the thermostat to open AT ALL. I had to pull the fan off to get it to tempreature high enough to open the thermostat. I am using a stock 195 and with the fixed fan the highest the thermostat would get is around 180. This was all verified with a infrared thermometer gun.
When I pulled off the fan everything worked as it should without a single hitch so that told me the fan is overcooling and not letting things get to where it needs be.
Regarding the fan yes I know that the fan needs to be specific but the fan pitch of the two fans I have is completely opposite. If I could see pictures of someones stock setup with a fan clutch it would be greatly appreciated because I'm spinning my gears right now.
You can even look at this fan http://www.summitracing.com/int/parts/hda-3618/overview/ from Summit Racing which says its a clockwise turning which would say that the fan with the clutch above is the correct one.
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My 83's clutch mechanical fan has uneven spaced blades. The 4.3's fan out of an 86 1/2 ton also had 3 blades.
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Yes over cooling. With that fixed fan on my truck I could not get the thermostat to open AT ALL. I had to pull the fan off to get it to tempreature high enough to open the thermostat. I am using a stock 195 and with the fixed fan the highest the thermostat would get is around 180. This was all verified with a infrared thermometer gun.
There's nothing wrong with your engine running at 180°F. In fact, I strive for that as a running temp. If the thermostat has no reason to open, then all the better. If you are concerned about the water flow...in that you would like the coolant/water to be running through the whole system regularly, then put a 160° or 180° thermostat in.
I'm not running anything stock. I have a higher displacement and a heavy handed street cam. I run a mechanical fan on my long water pump with a new 4-core all aluminum Camper Special rad with a one piece shroud. It all runs at about 183°F on average. When sitting here in L.A. traffic on a 90+° day, I'll watch my digital temp gauge creep.....sometimes to 205°F.....that's when I start getting nervous. As far as I'm concerned, the closer to 250°F, the worse. IMHO, 180°-200° is an ideal operating temp range. Overcooling?....no such thing.
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Well either way I need the thermo stat to open and I need to if the fixed fan about is correct of if the clutch fan is correct. Nobody seems to be giving me that answer.
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EDIT:
response temporarily withdrawn.
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Well either way... Nobody seems to be giving me that answer.
Option A
Step 1. Determine what temp you want to run at.
Step 2. Install appropriate thermostat per your answer to above.
Option A1.
Step 3. Install a mechanical fan that pulls air through the radiator.
Option A2.
Step 4. Install a clutch fan that matches your mechanical fan's direction and operates within the temperature range indicated in Step 1. (note: a clutch fan is optional)
Option B.
Step 3. Install an electric fan.
Step 4. Install a temp sending unit calibrated to the temp determined in Step 1 such that the fan turns on at the appropriate temperature.
Option B1.
Step 4. Install a switch on dash that controls when the electric fan turns on.
Option C.
Step 1. Follow Steps 1-3 of Options A & A1.
Step 2. Install an electric fan on the grill side of the radiator/ac condenser (if applicable) that pushes air through the radiator towards the engine block.
Step 3. See option B.
Option D.
Put the fan that "overcools" back on and drive your truck.
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Well either way I need the thermo stat to open and I need to [know] if the clutch fan is correct. Nobody seems to be giving me that answer.
Most clutch fans look the same. The temp range that the clutch is designed for is determined by the metal coil in the center (like the old mercury controlled heating and cooling thermostats that you may find in old homes). Unless you provide manufacturers and part numbers, no one will be able to tell you if that clutch fan will serve your needs.
Per the link you provided. The fan you show....the listing states that the fan is not recommended for engines larger than 250ci.....so, I would suggest you find one recommended for 350ci or more.
As well, that fan is a "standard, clockwise" rotation. It's not clear if you need that or a "counterclockwise" rotation.
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*sigh still no straight answers*
I am running v belt and need clockwise.
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Well that is the thing....I know the fan blades are opposite to one another and I had to take off the fixed fan because it was over cooling my truck...
(http://i.imgur.com/gKLVStc.jpg)
Option A:
Put that fan back on, nevermind the clutch, drive.
Option B:
Put that fan back on, put a clutch on...
http://www.summitracing.com/parts/flx-5555
http://www.summitracing.com/parts/hda-2747
http://www.summitracing.com/parts/hda-2797
etc...
...drive.
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You can't clutch that fan. That fan will not allow the thermostat to open.
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Ok, now that i thoroughly read your question i've determined that you ARE NOT running a serpentine setup AND you are running a conventional v-belt with conventional water pump. Correct?
Where did you get the fixed fan in the picture?
RE-EDIT:
i guess the better question is where did you get the clutch fan in the picture which has a tag of "76 chevy truck" on it?
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i just checked my 83 fan as well as the one that came with the 305 and they are both also pitched differently than the clutch fan pictured.
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Ok, now that i thoroughly read your question i've determined that you ARE NOT running a serpentine setup AND you are running a conventional v-belt with conventional water pump. Correct?
Where did you get the fixed fan in the picture?
RE-EDIT:
i guess the better question is where did you get the clutch fan in the picture which has a tag of "76 chevy truck" on it?
The fixed fan came on the truck. I know that there was A LOT of previous stuff done to this truck that was very questionable and this could possible be one of those things.
The picture with the clutch fan came from ebay which I know is also not necessarily a reputable source.
Is your 83 serp or v belt?
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1) Ok, in that case i would look for other fans that will fit 73-86 trucks. i think the ebay one may be incorrect. They may have meant 96 truck.
i don't think clutch fans were used until 80's ish, but by looking for fans starting in 73, we can look at the pitch angle.
2) my 83 is conventional v-belt. i don't think serpentine was used on trucks until after 87?
Now, i'm wondering how are you sure that the thermostat won't open? If the thermostat won't open wouldn't this mean the engine would eventually overheat?
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1) Ok, in that case i would look for other fans that will fit 73-86 trucks. i think the ebay one may be incorrect. They may have meant 96 truck.
i don't think clutch fans were used until 80's ish, but by looking for fans starting in 73, we can look at the pitch angle.
2) my 83 is conventional v-belt. i don't think serpentine was used on trucks until after 87?
Now, i'm wondering how are you sure that the thermostat won't open? If the thermostat won't open wouldn't this mean the engine would eventually overheat?
Because the coolant would be low and I would top it off and run the truck and it would be low again. It wasn't loosing coolant. You can tell when the thermostat opens because you can literally see the water flowing BACK into the radiator.
I was able to verify this as I replaced my 195 thermostat and with a temp gun watched as the housing hit 195 and the thermosat opened and the water flowed.
Since your 83 is v belt and you say the pitch is different I'm going to assume that when looking at the front the slant of the blade goes right to left not left to right? Like my original fixed blade?
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Yes---All of my fans are pitched like your original fixed fan.
But i'm a little confused regarding the thermostat issue; i thought that if the thermostat is closed then this means the water is ONLY circulating thru the engine, not the radiator---which means the engine would soon overheat?
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to say you "cant" over cool an engine is kind of a misstatement. keeping the engine temp too low and the fuel wont conver into heat like it normally would. heat is energy released during a combustion, so the cooler the engine runs the more heat that gets removed via water and cooled down in the radiator now and that heat is replaced by more heat from the next combustion. so if you have to remove heat it will get replaced by more heat and youre equivalently waisting energy.if we're talking intake temp thats a little different cause the cooler the more dense meaning more fuel you can add. the reason we have to keep the temps down is cause of metal problems and the most efficient temps would surpass the failure temp of most metals
But back to the fan, whats your coolant:water ratio?
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and has it always ran cold?
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At this point i would like to rescind and nullify all my previous comments and just sit back and observe.
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Yah I replaced the radiator, thermostat and new coolant. Working on the fan now and glad to have you here bd and glad to know I should have a clutch fan.
Now I just need to find one.
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My 74 k5 also the staggered fan with the fan clutch.
Not sure if it is 5 or 7 blades tho, I'm 700 miles from it right now.
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My 74 k5 also the staggered fan with the fan clutch.
Not sure if it is 5 or 7 blades tho, I'm 700 miles from it right now.
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Can you get me a picture of yours so I can have something to reference? Would be greatly appreciated.
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I will but it will be Thursday before I get home. Also it is factory original.
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Will do but will be Thursday befor I get home.
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i just want to interject that i had a 79 blazer with the 4 blade fixed (350) and automatic.
The 79 truck info packet (in the tech section) shows the 350, 305, 267, and 250 straight six as having the 4 blade fixed fan.
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Alright, it appears that automagics and/or air conditioned equipped trucks got the clutch fan while "standard" trucks got the fixed blade. (i'm looking at the 74 truck info packet)
Too sleepy right now, will continue tomorrow.
i'm not trying to confuse the issue and start an argument; i'm trying to learn as well.
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My 74 k5 also has A/C with the clutch fan 350 eng 350 trans.
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GM Parts Wiki: 1973-1978 CKP Light Trucks (http://www.gmpartswiki.com/getpage?pageid=60534)
Navigate forward and backward by clicking the page icons at the upper right and left of the GM parts page. Peruse to your hearts content.
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to say you "cant" over cool an engine is kind of a misstatement. keeping the engine temp too low and the fuel wont conver into heat like it normally would. heat is energy released during a combustion, so the cooler the engine runs the more heat that gets removed via water and cooled down in the radiator now and that heat is replaced by more heat from the next combustion. so if you have to remove heat it will get replaced by more heat and youre equivalently waisting energy.if we're talking intake temp thats a little different cause the cooler the more dense meaning more fuel you can add. the reason we have to keep the temps down is cause of metal problems and the most efficient temps would surpass the failure temp of most metals
::) Agreed. Such is why we seek to warm up our engine's before we drive. My statement was meant relatively....as in yes, if one were to, say, maintain their engine bay full with glacier ice for the sake of cooling, then it is arguable that they are overcooling their engine. Yes, engine heat is important to operational efficiency and yes, engine heat is different from intake heat. In this case, however, we're talking about a mechanical fan on an sbc 350, no? How a mechanical fan can overcool that size motor is a mystery to me. Maybe it's that I live in a warm climate....and so my reference point is different than someone in Alaska, for example. Nevertheless if there's an OE or stock mechanical fan out there that "overcools".....then I want one.
That said, I'm w Griffin now....and am going to just sit back and watch (and hopefully learn) this thread.
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My 1978 350, no A/C, fixed blade fan, would never reach operating temperature during half the year. The bleed on the thermostat was enough to overcool the engine with cold ram air through the radiator and the fan always running. I went to an electric fan that only turns when needed, now no problem maintaining operating temps regardless of outside temps.
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to say you "cant" over cool an engine is kind of a misstatement. keeping the engine temp too low and the fuel wont conver into heat like it normally would. heat is energy released during a combustion, so the cooler the engine runs the more heat that gets removed via water and cooled down in the radiator now and that heat is replaced by more heat from the next combustion. so if you have to remove heat it will get replaced by more heat and youre equivalently waisting energy.if we're talking intake temp thats a little different cause the cooler the more dense meaning more fuel you can add. the reason we have to keep the temps down is cause of metal problems and the most efficient temps would surpass the failure temp of most metals
::) Agreed. Such is why we seek to warm up our engine's before we drive. My statement was meant relatively....as in yes, if one were to, say, maintain their engine bay full with glacier ice for the sake of cooling, then it is arguable that they are overcooling their engine. Yes, engine heat is important to operational efficiency and yes, engine heat is different from intake heat. In this case, however, we're talking about a mechanical fan on an sbc 350, no? How a mechanical fan can overcool that size motor is a mystery to me. Maybe it's that I live in a warm climate....and so my reference point is different than someone in Alaska, for example. Nevertheless if there's an OE or stock mechanical fan out there that "overcools".....then I want one.
That said, I'm w Griffin now....and am going to just sit back and watch (and hopefully learn) this thread.
Perhaps the term "overcooling" is being taken out of context but what else would you call it when you can't get your thermostat to open properly and allow the engine to run at an optimal temperatue?
I live in a cooler region and when the fan was running all the time the radiator would only be at 41* F and never go any higher so the truck could never run efficiently.
With a new rad, thermostat and fresh coolant my truck is cooling to a point where it won't run efficiently and I need to fix that which is going to be done by removing the fixed fan for a clutch fan.
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No I don't believe over cool is the wrong term. But it can be taken a couple different ways. But like said the main problem is the fixed fan instead of a clutch fan.
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I think your plan to add a fan clutch is sound.
My '75 350 K10 does not have A/C, does have a fan clutch, and engine temps run rock steady once warmed up.
Here is a quote from the GM 1973 CK service manual:
"Automatic fan clutches, Figure 6, are hydraulic devices used to vary the speed in relation to the engine temperature. Automatic fan clutches are used with many engines, especially those equipped with factory installed air conditioning units. Automatic fan clutches permit the use of a high delivery fan to insure adequate cooling at reduced engine speeds while eliminating overcooling, excessive noise, and power loss at high speeds."
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What was the original question? ;D
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What was the original question? ;D
Will this fit my....
This has been an interesting conversation to which admittedly I added some BS.
However....
All blame for off topic banter falls entirely on HAULIN IT and his hilarious "Fred the Fan Man" rant.
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This is the stock, original fan off my buddy's 79 GMC K2500 High Sierra. It is exactly the same as the fan off my old 79 Chevy C20 Camper Special.
My truck came from the factory with a 4 core radiator, sb 350, turbo 350 and ac.
His truck came from the factory with a 4 core radiator, sb 400, turbo 400 and ac.
(http://images.tapatalk-cdn.com/15/05/18/ae299d87fe4fc89c2950fed9d16a383d.jpg)
(http://images.tapatalk-cdn.com/15/05/18/57400a7bc5890d697356b533ae381114.jpg)
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Perfect. The pitch is completely different and gives me a good perspective.
Apparently clockwise fans tilt towards the left and counter fans tilt towards the right.
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Here is a quote from the GM 1973 CK service manual:
"Automatic fan clutches, Figure 6, are hydraulic devices used to vary the speed in relation to the engine temperature. Automatic fan clutches are used with many engines, especially those equipped with factory installed air conditioning units. Automatic fan clutches permit the use of a high delivery fan to insure adequate cooling at reduced engine speeds while eliminating overcooling, excessive noise, and power loss at high speeds."
Fan clutches are great. They make for better fan efficiency and motor performance, no doubt.
For the record, some of the earliest automobile fan clutch patents go back to the mid-late 60's. By mid 70's nearly every auto company was applying for fan clutch patents....electro-magnetic, viscous, electro-viscous, electric, etc. fan clutch patents were being applied for....and still are well into 2015. None of the early patents speak of "overcooling" as a problem with internal combustion engines and none seek to solve the "problem" of overcooling. Every one of the patent applications (including those filed in the 21st century) seek to produce a more efficient cooling component in the engine (i.e. the fan). The myriad inventors of the fan clutches (including GM), all discuss the loss of HP when a fan that is directly connected to the water pump pulley and in constant motion and is forced to wrestle against incoming air, particularly at increased speeds.
1. If a fan without a clutch is inefficient but "overcools" anyways....it logically follows that by adding a fan clutch, and therefore producing a more efficient cooling mechanism, then the clutched fan would "overcool" even more.
2. I suppose then, all of the GM autos made before the invention of the fan clutch just simply, never heated up. Thank you Fred the Fan Man....you saved the world of autosports and made driving possible.
3. Despite what the holy grail service manual says...I doubt that "overcooling" was a problem that GM ever had with the sbc 350.
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SBCs tend to run cold, BBCs tend to run hot. The issue with the SBC isn't having it run cold in hot weather, obviously. The issue is getting it up to operating temp when the ambient is (in my case anyway) below about freezing.
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Perfect. The pitch is completely different and gives me a good perspective.
Apparently clockwise fans tilt towards the left and counter fans tilt towards the right.
Welcome. I felt for ya a little cuz we have the philosophy of the fan goin on here and no one yet had posted the pic you wanted. So figured I'de help ya out.
Now we can get back to the movie "Fanology". Lol
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Mines a 7 blades and is slightly staggered.
Pictures are the best I could do without removing the fan.(http://images.tapatalk-cdn.com/15/05/21/fed05e9693307f0640d9b3fbec08ac20.jpg)
(http://images.tapatalk-cdn.com/15/05/21/896369825615075072c6d9909ccbda4f.jpg)
(http://images.tapatalk-cdn.com/15/05/21/fafac72e859cc6f5fb25421768df0365.jpg)(http://images.tapatalk-cdn.com/15/05/21/a2acebc0693f79f0c931d571e071a574.jpg)
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That is perfect. It again shows clockwise fans tilt towards the left not the right!
Thanks man.
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Welcome
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Found a nice 6 blade today at the wreckers. Gonna be installing it in a few.
So I need a few more answers to things. I need some much needed measurements to now check and see if my rad shroud is proper size.
I measured the ID of the shroud for the fan blade and got 21 3/8"
I measure the depth of the fans shroud and got 5 1/2"
I measure the amount of blade sticking out and get 1"
I also have a 4x4 with no AC if that might make a difference.
Part # 6264137
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That little fan in the first pic looks like may be for a 6 cylinder. Never seen one with such stubby little blades before on a V-8. The 6s were a smaller diameter.
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So just thought I would update this thread.
With the new 6 blade fan, new hayden HD clutch fan and heater core I am unable to get my truck to proper temp :(
This is frustrating..
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Thermostat? You can have all the great cooling stuff in the world, but if your thermostat is stuck or not working, it's never gonna warm up.
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thermostat was replaced and tested before. the only way I have yet to see this truck warm up properly is without a fan.
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Did you put the 180 degree thermostat in it? If you put a 165 degree one in it will never blow hot air out of the heater. The coolant will circulate too fast at a low temp.
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BTW- my 79 came with a fixed blade fan and I replaced it with a clutch fan. I have never had the issue that you are having. I also did have a brand new thermostat stick shut on me the very first time I fired a new engine up. You might have to get another thermostat. Yours might be defective.
My shroud dimensions are: 7 blade fan, shroud is 7 inches deep, the fan blades are inside the shroud 1/2 inch and the inside diameter is 22 inches + or - a little bit.
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I put a 190 into it. But using a infrared gun the water neck never gets over 170-175* F
I am going to put a block off plate so less air gets to the water neck to see if it helps.
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195 is stock temp. Maybe a 200 or 210, I know it's higher but maybe it will compensate and get you up too the proper temp. Besides, a 350 will run 210 no problem.
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Sorry yah its a 195 lol.
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If the thermostat isn't opening, then coolant is never exchanging between the block and the radiator, so your water neck will always be the temp of the coolant in the radiator. I would use your thermometer to check the temp of your intake and heads.
The only way the fan can be over-cooling if the thermostat is not opening, is if it is pushing enough air over the block to air-cool it (like a motorcycle or old VW engine). If that's the case, I would begin to suspect how well the engine is running
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These may sound ludicrous, but (1) how are the heater hoses plumbed, and (2) what happens if you pinch off the heater hoses?
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If the thermostat isn't opening, then coolant is never exchanging between the block and the radiator, so your water neck will always be the temp of the coolant in the radiator. I would use your thermometer to check the temp of your intake and heads.
The only way the fan can be over-cooling if the thermostat is not opening, is if it is pushing enough air over the block to air-cool it (like a motorcycle or old VW engine). If that's the case, I would begin to suspect how well the engine is running
Well ironically when I pull the fan off the thermostat will open just fine and work as normal. What would cause a vehicle to not run right to cause this though? You are basically saying the engine itself is running cool.
These may sound ludicrous, but (1) how are the heater hoses plumbed, and (2) what happens if you pinch off the heater hoses?
The proper way... 3/4 to pump
I will check the temps of the heads on the next test.
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Top hose goes to the water pump and the bottom hose goes to the intake. I know you know but just so you don't get confused. Just tryin to help. :)
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These may sound ludicrous, but (1) how are the heater hoses plumbed, and (2) what happens if you pinch off the heater hoses?
The proper way... 3/4 to pump
So does clamping off coolant flow through the heater have any effect whatsoever?
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These may sound ludicrous, but (1) how are the heater hoses plumbed, and (2) what happens if you pinch off the heater hoses?
The proper way... 3/4 to pump
So does clamping off coolant flow through the heater have any effect whatsoever?
Haven't tried yet. Curious what this will accomplish?
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Well ironically when I pull the fan off the thermostat will open just fine and work as normal. What would cause a vehicle to not run right to cause this though? You are basically saying the engine itself is running cool.
Usually an engine will run cooler than normal if it's running rich, it's not firing all cylinders, or the outside ambient temp is very low.
Being June, we'll assume it's not below freezing outside. Running that rich I would expect you'd notice black smoke from the tailpipe. I've seen engine run on only one bank and still feel fairly smooth, so you might check the temp of the exhaust manifold near each valve, those should be decently consistent.
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kind of going of what tim said but just curious whats your timing set at?
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Well ironically when I pull the fan off the thermostat will open just fine and work as normal. What would cause a vehicle to not run right to cause this though? You are basically saying the engine itself is running cool.
Usually an engine will run cooler than normal if it's running rich, it's not firing all cylinders, or the outside ambient temp is very low.
Being June, we'll assume it's not below freezing outside. Running that rich I would expect you'd notice black smoke from the tailpipe. I've seen engine run on only one bank and still feel fairly smooth, so you might check the temp of the exhaust manifold near each valve, those should be decently consistent.
You would be correct and on most days lately its been well above 15 degrees celsius. No black smoke to be seen at all and I will definitely check the exhaust manifolds to see what they say.
kind of going of what tim said but just curious whats your timing set at?
Right now its running at 16* BTDC.
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Ok so I did some testing.
Truck warmed up and running for 30 minutes.
Cylinder temps on the head just above the ports is betweem 280-380 with 7 and 8 running cooler.
Water neck gets up to 182-185. If I wrap the water neck with insulated bubble wrap I will seen a immediate increase in temps of 193-195
Also water pump pulley is smaller than the crank pulley. Water pump pulley is 6.25" and the crank pulley is 6.75-7"
So by wrapping the water neck I am seeing a 10 degree increase of temps which leads me to believe my fan is blowing too much cold air.
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Water pump pulley being smaller than crank pulley is normal.
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Water pump pulley being smaller than crank pulley is normal.
From what I have read it's not. It seems it's normal for the crank pulley to be smaller or have them run in a 1:1 ratio.
With my water pump pulley being small it's turning faster that the crank which pushes coolant faster and I am thinking not allowing it to absorb heat and thus never getting warm enough.
I have tried to find what stick size is normal but I am unable to find that information.
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I went out and measured my water pump pulley and it is 6 1/8 inch diameter. That is the OD of the pulley not down in the V. This has been on the truck since I bought it and I am sure it is the original one.
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I went out and measured my water pump pulley and it is 6 1/8 inch diameter. This has been on the truck since I bought it and I am sure it is the original one.
So your water pump pulley is smaller than mine.
What size is the crank pulley?
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I went out and measured my water pump pulley and it is 6 1/8 inch diameter. This has been on the truck since I bought it and I am sure it is the original one.
So your water pump pulley is smaller than mine.
What size is the crank pulley?
I was afraid you were going to ask me that. I will go back out to the garage and try to measure. I don't know how exact this one will be. I will report back in a few.
OK near as I can tell mine is 7 inches. This is a two groove pulley. It is also a factory pulley that has been on the truck its whole life.
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What kind of water pump do you have on it? Is it some high performance model or something? Mine was bought from O'reilly's last year.
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dang throws that theory out the window. guess it's back to the drawing board.
just a stock water pump as far as I know.
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dang throws that theory out the window. guess it's back to the drawing board.
just a stock water pump as far as I know.
Sorry. :( Just tryin to help. :)
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Well then beats the heck out of me. Hey brain storm idea! What happens if you cover say 1/3 of the front of radiator? Either vertically or horizontally. You probably have to pull the upper radiator support for this experiment but it's only 4 bolts.
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I just keep coming back to the water pump. I think it is circulating coolant too fast. It is either the fan blade, the thermostat or the impeller in the water pump. I don't know.
Possible answers
The thermostat is opening too soon and engine can't get up to the correct temp.
The impeller is the wrong one and the water pump is circulating coolant too fast.
The fan blade is wrong size and spinning too fast- working too good.
I am probably wrong.
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So just thought I would update this thread.
With the new 6 blade fan, new hayden HD clutch fan and heater core I am unable to get my truck to proper temp :(
This is frustrating..
He mentioned he has an HD fan clutch. Is it possible the clutch is working to good just because of the way it's built. Maybe a for a 1 ton truck with a big block or something? Isn't his truck a 3/4 ton? Maybe switching to a new standard clutch would be better. Again, shot in the dark here.
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These may sound ludicrous, but (1) how are the heater hoses plumbed, and (2) what happens if you pinch off the heater hoses?
The proper way... 3/4 to pump
So does clamping off coolant flow through the heater have any effect whatsoever?
Haven't tried yet. Curious what this will accomplish?
Coolant flow through a SBC is radiator to water pump through lower hose - water pump to block water jackets - block water jackets into cylinder heads - cylinder heads to intake coolant crossover, thermostat and water outlet - water outlet to radiator via upper hose - through the radiator and back to the engine. The heater hoses are connected to the intake water crossover and water pump. Heater core plumbing bypasses the engine thermostat, routing coolant directly from the water crossover below the thermostat through a mini radiator under the dash and back to the water pump and engine.
Have you ever pondered why the factory incorporated a 1/2" restriction into the 5/8" heater hose fitting that threads into the water crossover? You posted that on a warm day ambient temperature is ~5° C (~40° F). How do you suppose coolant bypassing the thermostat through the heater core might affect engine temp on generally cold days, especially if your engine is on the threshold of over cooling anyway, because of high heat rejection from a large radiator and high airflow? If you or the PO replaced the 5/8" hose nipple with an open fitting, symptoms could be further exacerbated.
Pinching a heater hose off to see whether it has any effect takes all of one minute. It may have no effect at all. But, until you try it, it remains an unknown. All I'm attempting to do is offer you some assistance based on more than just a little experience. Don't overthink it.
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a) will be doing the radiator cover up test tonight
b) will try pinching the heater line
c) whether I use the hd fan clutch or normal clutch same issue
d) two different fan blades used; same issue
e) if the thermostat was open I would see flow in the radiator which I do not.
The 5/8 nipple is supposed to have a restrictor? How does one know if it does?
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The 5/8 nipple is supposed to have a restrictor? How does one know if it does?
OE restricted fittings are steel and have unusually thick walls, creating an ID of approximately 3/8". If the existing fitting is brass, it's not restricted. If the fitting is steel, you'll need to remove the hose and inspect the ID of the fitting. The restriction is visually obvious. But, first, pinch off the hose to see if there is any effect on engine temp and whether it's worth pursuing.
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That makes sense bd. I never thought about the fitting being changed out. That would explain why the coolant is circulating too fast thus the low temp. I know I would have never thought of the fitting. This problem is a real head scratcher for sure. I think several of us have learned a thing or two with this thread.
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So beyond running cool, is the engine doing anything weird?
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That makes sense bd. I never thought about the fitting being changed out. That would explain why the coolant is circulating too fast thus the low temp. I know I would have never thought of the fitting. This problem is a real head scratcher for sure. I think several of us have learned a thing or two with this thread.
Coolant circulating too quickly generally has the opposite effect - overheating. Diesels are particularly sensitive to this. The coolant absorbs heat from the engine, but circulates through the radiator too quickly to transfer the heat to the surrounding air. High volume water pumps are designed to increase coolant flow below ~3,000 RPM, but can cause cavitation above ~6,000 RPM. Remove the thermostat or constrictor plate from an engine with high coolant flow and it might overheat.
Whether or not coolant bypassing the thermostat through the heater is the cause of the OP's powerplant running cold is yet to be determined. It will be a relief if that simple.
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So beyond running cool, is the engine doing anything weird?
Nope it runs perfect otherwise! Its just really aggravating that its doing this because where I live the temperature can fluctuate enough that this could cause bigger issues.
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That makes sense bd. I never thought about the fitting being changed out. That would explain why the coolant is circulating too fast thus the low temp. I know I would have never thought of the fitting. This problem is a real head scratcher for sure. I think several of us have learned a thing or two with this thread.
Coolant circulating too quickly generally has the opposite effect - overheating. Diesels are particularly sensitive to this. The coolant absorbs heat from the engine, but circulates through the radiator too quickly to transfer the heat to the surrounding air. High volume water pumps are designed to increase coolant flow below ~3,000 RPM, but can cause cavitation above ~6,000 RPM. Remove the thermostat or constrictor plate from an engine with high coolant flow and it might overheat.
Whether or not coolant bypassing the thermostat through the heater is the cause of the OP's powerplant running cold is yet to be determined. It will be a relief if that simple.
Well good news and uh weird news?
Pinching the heater hose still did not help. But placing a chunk of plywood in between the fan and radiator did.
So now I have discovered again that something is over cooling such as my fan or my water pump is being twerky...
Thoughts?
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All this talk about fans, whats the most common size? 18 in. ?
Im putting these two together. Good?
(http://uploads.tapatalk-cdn.com/20160213/b90350d311abd4749f82f49deb267ae0.jpg)
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All this talk about fans, whats the most common size? 18 in. ?
Im putting these two together. Good?
(http://uploads.tapatalk-cdn.com/20160213/b90350d311abd4749f82f49deb267ae0.jpg)
i measured the v-6 3-bladed fan off the 4.3 and it's 18". The v-8 fan that came with my truck is about 20"+ a little bit.
My opinion is that you'll generally be ok as long as you're not towing or hauling heavy----because will that 18" fan fit the stock shroud the way the stock fan did and provide maximum cooling?
Since we brought this thread back i have a few questions of my own:
1) What is the normal operating temp for a small block from the factory?
i believe i put a new 195 thermostat in the 4.3, but it won't go higher than 180 according to the gauge. i "think" i would like to run a little hotter---maybe 195 to 200.
i am using the stock v-8 radiator (yes the hoses from a v-6 basically hook right up, more about this in my swap post) AND i don't have any fan. Yes risky i know, but it's winter and i'm going to be installing an electric fan asap.
Heater works just fine.