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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: micahadams on February 08, 2010, 11:51:55 pm
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84 C30 454/th400
I have been having cooling problems and now I am ready to do almost anything to solve it. I have changed to a new aluminum 3 row rad, 160 stat, then changed to a 160 high flow stat, dual e fans, new water pump, new hoses, flushed the system 3 times, disconnected egr, then re connected it. Straight water, then tried adding water wetter. Not much has helped.
It will idle cool(160), run on the freeway cool, but anytime there is a hill or I am pulling my trailer it will climb to 210+.
I was talking to a guy today who said Chevy in the 80's needed to conform to smog laws and to get the motors to pass needed to retard the cam timing -9 degrees. I have also heard that 80's heads have small water ports.
Here is my question. Has anyone has a cooling problem and found a way to fix it? I am thinking maybe a cam change will help, or a adjustable cam gears. I haved owned several small blocks that ran fine. This problem seems to happen to a lot of BBC's
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Do you have a spring in the lower radiator hose? Do you have the belt routed correctly? Is it actually overheating or are you just seeing your gauge rise?
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these trucks are just so hot anyway they naturally run hot lol
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Does you truck have cats on it and is it possible that they could be stopping up. I have never seen 200 on any of my bigblock trucks when pulling, so I was curious if maybe your exhaust is restricted.
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Yea I have the spring in the lower hose. No cats. Thorley tri y's with x pipe and flowmasters. Timing is 36 degrees total. In the summer w/ the A/C on or off I can get it to boil over.
It has to be something to do with all the smog stuff. I just dont get how new cars these days have radiators the size of school books and they run perfect, but I have a monster of a radiator and it still runs hot. I think I am going to try to change the cam and intake and see what happens.
Any other thoughts?
Choptop, tell me more about your motor.
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coptop may be on to something. I know in my 79, years ago, it would overheat without any apparent reason. I found out the cat was clogged with junk and restricted the exhaust flow, which backed up the pressure and caused the engine to overheat big time.
It should not overheat just because of smog stuff unless you have real problem.
You can have reverse rotation water pumps, bad t-stadt (even though it's new), clogged radiator paths, timing is off, bad exhaust flow, etc...
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Does the radiator also cool the trans fluid on your? If so the trans runs ALOT hotter than the engine. I had an overheating issue once when i got my 2wd almost stuck in the snow. By shifting from forward to reverse so many times and not having adequate airflow the tranny heated up and transferred the heat through the radiator to the coolant causing the engine to overheat. Might be worth looking into. Check your tanny fluid level and smell it to find out if its burnt. If it smells burnt The problem would be caused by the tranny. Just a suggestion.
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I have checked the t stat by boiling it, if opens fine. Radiator is brand new. I even drained the bottom drains on the block incase there was any crud in there. The trand fluid runs into the rad 1st, then into a aux cooler. Fluid looks and smells fine.
Part of the problem is a 454 that only put out 245 hp. The throttle is open pretty far just to get the truck moving with a trailer.
I check the a/f with a wideband o2 and it never runs lean either.
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Run it with a spill free funnel on it and see if you are getting any bubbles.... If you're positive everything is correct and it's still overheating you probably have a head gasket on it's way out or some seriously clogged coolant jackets. Don't blame your cam
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The only reason I blame the cam and its timing is because my parents in 1986 bought a Deluxe 20 with the same motor trans combo 454/400 and it would overheat on them all the time. They owned the truck up until a few years ago and always had problems with it. They added a custom made huge radiator, ran the stock clutch fan with aux e fan pusher. It only has a temp warning light so no way to tell if its running hot till its too late but while towing the light would come on.
A friend on mine also had a mid 80's Chevy dually and it would over heat. I remember someone saying that in the 80's the ford 460 needed to be ran at 6 degrees BEFORE tdc to pass smog.
I dont think its the head gasket because there is no water in the oil and vice versa, and it only happens when pulling a long hill. Its not like the cylinder pressure is pressurizing the cooling system, as for as I know.
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Is the fan shroud intact? Is it the correct fan and clutch for the truck?
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Correct fan shroud and a 180-195 t stat. betting the 160 isn't leaving the water in the radiator long enough to cool off.
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I have dual electric fans now that pull 2600 cfm. But with the old setup I did have the correct shroud and fan.
I though about the higher temp t stat but am not convinced it will solve my problem.
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It won't fix your problem unless you have a faulty t-stat now. The polarity of your fans is correct right? Did you have this problem with the fan shroud and clutch fan? If a head gasket is leaking it doesn't mean you will mix coolant with oil.
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Yea i am just trying to think of everything. Yes fans are wire correct. They are on an adjustable thermostat. What I did to test them is turn up the adjustable knob till the truck got to about 200 degrees at idle, then turned the knob till they turned on. It cooled the water down fast, but thats at idle when the motor isnt making much heat. With the stock fan and shroud it ran hot too. The e fans helped, it just seems like when putting a load on the motor nothing will cool it.
I was joking with my buddy about putting my old radiator in the bed of the truck and using the dischage line of the heater core to circ the water from the "bed" radiator to the main raidator. I know if doesnt really help the cooling of the system with removing heat, but it would add cooler water for a certain amount of time.
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One other thing about your fans even if the polarity is correct, make sure the blades are not reversed. Many come set up as pushers and require the blades to be flipped and the polarity reversed to actually work correctly.
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Hmm, so I guess I am just trying to understand...In the first post you said it goes to 210 while going up a hill. Later it was that it will boil over. Does it boil over at 210? What temperature does it get up to?
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What shape is your radiator cap in? If its not holding correct pressure then the engine will boil over at lower temps. The pressure in the system is what keeps the coolant from boiling at lower temps.
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Its nothing simple like the cap. I have tried 3 different caps and I can feel the pressure in the system(squeezing the rad hose) when its hot
It will shoot up to 210 pretty quick up a hill, if the hill is long enought it will boil over. I think the hottest I have ever remember driving it at was 235 range. After driving it hot around 210, when I shut it off I can hear water boiling in the head/manifold area. It does not boil over at 210
My plan is to pull a valve cover and set up my magnetic dial indicator, bolt up a degree wheel and see what the cam timing is. The guy I talked to said the timing chain and gear are cast so the cam is retarded.
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I had tried everything, but my 454 would still overheat when I hit a hill. I finally decided to pull the motor and freshen it up.
The PO wasnt much for maintenance. The water ports going into the heat were completely sealed up with build up. Another reason running straight water is a bad idea.
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84 C30 454/th400
I have been having cooling problems and now I am ready to do almost anything to solve it. I have changed to a new aluminum 3 row rad, 160 stat, then changed to a 160 high flow stat, dual e fans, new water pump, new hoses, flushed the system 3 times, disconnected egr, then re connected it. Straight water, then tried adding water wetter. Not much has helped.
It will idle cool(160), run on the freeway cool, but anytime there is a hill or I am pulling my trailer it will climb to 210+.
I was talking to a guy today who said Chevy in the 80's needed to conform to smog laws and to get the motors to pass needed to retard the cam timing -9 degrees. I have also heard that 80's heads have small water ports.
Here is my question. Has anyone has a cooling problem and found a way to fix it? I am thinking maybe a cam change will help, or a adjustable cam gears. I haved owned several small blocks that ran fine. This problem seems to happen to a lot of BBC's
Sounds normal to me for a 454. My 454 is the same way. Its got a 195 T stat in it. runs the guage at about 200, but if I am towing and climbing a grade, its get to 230 or so and even 240 on a long grade. I knew my timing was a bit advanced, so I put it back where it was supposed to be, and now its normal to hit 220 climbing a grade, and as high as 230, but never seen it above 230 since I set the timing back down. You may check your timiing and see where its at. Sounds dumb I know, but it could be our issue. I also do not have have any Cats either.
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Timing definitely impacts the temperature.
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Thanks for the back up Capt. Many don't beleive so, and why I said, I know it sound dumb. But that was the only thing I could think of could be my problem, and it seemed to cool it down about 10 degrees. But I think these 454's just run warm by nature. Also, 230 in not really overheating. With antifreeze and a 13lb pressure cap, your boiling point is raised up quite a bit higher, and running 230 should not hurt anything. But, an added trans cooler would be a good idea since the radiator tank is going to be hotter, and not be as effective as cooling the trans fluid.
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Timing definitely impacts the temperature.
so does biger cam and small exhaust valves., leaned out..
i have a 180* t-stat adn a 208/214* cam .475/500 lift(smallest aftermarket cam) with 049 heads... with a 19" 6 blade mech fan i saw 210* in 4000lb vehcile cruising
valves were 2.06/1.72 rebuilt the engine went to 1.88 exhaust.. i am now runign within 1-2* of t-stat temp. BTW my coolant prob is in the cylinder head between #3 and #5 cylinder b4 and after engine build
aslo were is yout collant temp probp at? by the t-sate or in the cylinder head? the cylinder head will read hotter then the manifold since it sitting between two exhuast ports..
also i would get a infra red gun and reading off the t-stat housing.