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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 74chev4x4 on August 30, 2010, 01:39:04 pm
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OK just got my new 350 in the truck took it over to have the headers fit to the pipes and noticed my temp gauge in the cab is not working now when it was with the 454 before motor swap. I bought a new sender for the 350 but is there one for a temp light and one for the gauge, this was the case on my toyota and I blew the guage because I hooked up the sender for the light and not the gauge. Hopefully this makes sense. Also I ran if for prob 15 min each way barely doing 40 mph noticed my rad hoses never got up to pressure not sure if the tstat is not opening or if I didn't drive it enough to get it to open, just scares me cause the temp gauge is not working and I dont want to warp heads on a brand new motor by overheating. Any adivice from u guys is always appreciated thank you!
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OK just got my new 350 in the truck took it over to have the headers fit to the pipes and noticed my temp gauge in the cab is not working now when it was with the 454 before motor swap. I bought a new sender for the 350 but is there one for a temp light and one for the gauge, this was the case on my toyota and I blew the guage because I hooked up the sender for the light and not the gauge. Hopefully this makes sense. Also I ran if for prob 15 min each way barely doing 40 mph noticed my rad hoses never got up to pressure not sure if the tstat is not opening or if I didn't drive it enough to get it to open, just scares me cause the temp gauge is not working and I dont want to warp heads on a brand new motor by overheating. Any adivice from u guys is always appreciated thank you!
There are specific "dummy light" and specific gauge sending units. If I remember right, they do have different connectors between the two. It's possible to have gotten a new bad unit; it happens from time to time.
It sounds like possibly the thermostat may be stuck open. when stuck open it makes the engine take a lot longer to get up to operating temp. If the thermostat was stuck shut, it should have overheated pretty quickly.
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I would have known if I overheated it right I was taking it real easy coming back from the shop?
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ok fixed that the wire was loose and temp gauge is working now. So the gauge goes right to red after a few minutes of idle. I have no pressure in my radiator hoses, but there is coolant in the block because I had a bunch spill out when I changed the temp sensor. Not sure what else to check the water pump is new and so is the thermostat so I'm guessing its one of the two?
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just boiled the tstat and it opened up so now what is the radiator clogged
?
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i'd run it without the tstadt just to rule it out. see what the guage does.
could be the water pump. since it is a new engine, could be the gaskets (head, intake, whatever) may be covering some coolant arteries in the engine.
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sorry meant new to me, it was rebuilt about 15k ago, I put new valve covers oil pan water pump and intake on it. So I just drained the coolant and ran water from the top of the radiator on the drivers side and it came flowing out the bottom hose on the pass side so the rad is not clogged. The wp is new which means that it can still be bad, anything else I should check before pulling the wp?
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It's not actually overheating just the gauge reads hot? You probably installed the wrong sending unit. There is one for the gauge and one for the idiot light as 78Chevyrado already pointed out to you. What part # did you install? Use the one from the 454 if you still have it.
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vilezombie man I need ur help, I think I have the right sending unit the wire was messed up is all part # wt203 borg warner I believe. There is no flow in this system, I pulled the water pump looked down in it with a light and can see all the blades moving and they all look fine. I stuck the hose in both ports on the block where the wp mounts and blew water in it and it comes back out, doesn't seem to blow from one side to another though not sure if it should? So Im stumped, I keep hoping in the back of my mind that I didn't overheat it this morning when I drove it. I pulled the heater hose going to the wp and there is no coolant in the heater hose? Also does it matter which hose goes where on the firewall for the heater core I have the top hose going to the wp. Sorry for the 50 questions man I just wanna get this thing done tonight. Thank you
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Did you fill the system and bleed it before you closed the system?
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When I first filled it I didn't burp it if thats what u mean. It was too loud with just headers to do that and I didn't think about it this morning :'( . I should have been able to do it anytime after that right?
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Fill it through the intake manifold with the t-stat removed. Put the thermostat in and fill it the rest of the way through the radiator. Run it until the thermostat opens then put the cap back on. Get one of these too
http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=4111
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gonna go get one right now, thanks man! So would I have known if I messed my motor up this morning? didn't get on it at all and pulled over a few times. 15 min drive there and 15 back with about an 45 min cool down in between? Thanks again
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I guess you'll find out when you get the system filled up
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yea true, one more thing, when I was running water throught the coolant holes where the wp mounts up should it have come out the other side or do those jackets just go on one side like the one on the left only goes around the left cylinders and does not connect to the right collant jacket or is this my clog?
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So put the new wp on filled it with coolant through the intake, put tstat back on filled the rad started it and nothing. It doesn't even act like its trying to flow anything. I don't know what else to check its so frustrating. Truck has been sitting for 5 months and I just want to drive it now and I can't. Well if anyone has any ideas I'm open to them, thanks guys!
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Any thoughts on it being or needing a reverse flow pump?
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thats a good point! Does anyone know what kind of application a reverse pump is needed. Mine possibly.
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Usually on a serpentine belt system. What's the part # of the water pump? I doubt that's the problem, but it could be!
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I think they are only needed when the belt reverses the direction, like in a serpentine setup, which makes it CCW. The block wouldnt matter.
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yea just looked that up and saw that, shoot
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It must be blocked somewhere than right? If I put the wp back on and filled the coolant throught the intake Tstat hole then the wp should be full of coolant and shoot just start shooting it down the rad hose and into the rad? I dunno.
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not sure about the part # on the wp, just asked for one for a small block and told them what truck I have. It must be something simple?
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Im pretty sure you would have known if your engine got hot, might have had steam and coolant everywhere, but might not have.
It doesnt matter which hose goes to which end on the heater core, except I think they are two different sizes, so technically it does matter.
Do you still have the box for the water pump to get the PN? Shouldnt matter, but its something to rule out.
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I just R and R my radiator, and to make sure everything was tip top, I filled the radiator with fluid and ran the truck with the cap off. The water level dropped because it was replacing the air inside the engine. I kept topping it off until it was good. I knew my WP was good because I could see the heater hose line shooting water back into the radiator. After a few days of driving it, i topped the radiator off again.
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yea right where the cap is the heater line should be shooting coolant back in i remember doing the same thing with my 454 but I had flow then. 511584 is the part number its a carquest wp.
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that's std rotation then.
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might try filling up the heater lines just to rule that out as an air bubble in the system because nothing has really gone into the heater core or lines yet.
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ran water through the heater hoses then hooked it back up and ran it with the cap off and still nothing, God is it the motor or the truck. If its the motor I will just rip it the heck out of there and put another one in its just money and this truck sure eats that!
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Are you sure you're not installing the thermostat upside down?
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spring down pointed end up right
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right, you want the sensor part in the block's water.
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Should the water jackets where the wp mounts flow all the way around eachother cause I put the hose in the block in the water jacket when the wp was off and sprayed water in each side and they build up water and come back out the same side. I thought it should have came out the other side of the block. Talking about where the wp flow coolant.
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just looked on my 454 thats in the garage and I don't think they are supposed to so its fine in that respect.
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What makes you think there is no flow? how are you checking it? Are you saying if you pull off a heater hose and start the engine no coolant comes out?
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Cause the hoses have no pressure and I can open the cap and see nothing moving. Nothing in the heater hoses its not flowing. Now motor has a noise like a loud exhaust leak but it sounds internal this sucks.
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Again, if you pull off a heater hose with the engine running no coolant pumps out is what you are saying correct? You will not see coolant flowing through the radiator unless your heater core return goes into the radiator and the level is low.
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Yea no coolant comes out correct.
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Then there is either no coolant in the engine or the impeller is broken. As soon as the water pump starts rotating coolant is pumped into the heater core. This is the bypass side of the circuit.
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OK update, pulled the tstat out and ran it without and it pumps fine? Truck does not get hot now and is pumping coolant fine. What should I do when I go to put a new tstat back in or what kind to buy dont trust the new old one?
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Put it in a boiling pot of water and see if it opens. They also make fail safe t-stat that if they do fail they stay open there a little more but if you want to be stafe. me I just use autozones haven't had bad luck with them
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yea that was the first thing I did before I changed the wp or anything else, it opened up in boiling water but wouldn't up in the truck? Took it out and the cooling system is fine.
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It does take longer to open in the engine than a boiling pot of water. Just put it all back together and run the truck for a few minutes.
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with a new tstat right, I have been running it with out the tstat and its great.
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The only problem with that is it might run cooler in the winter it might not heat as well as you want
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There is no reason to run without a Tstat.
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OK so I just got a new fail safe tstat and put it in tried to keep the rad cap off for as long as possible then put it back on. The temp gauge said the truck was hot but I let it go for a few min longer cause it was just idling in the driveway. The hoses pressurized so the tstat must have opened. The only thing is its still saying the truck is running hot. If i start to drive at all it says hot, stop and it goes down a bit, truck showed no sign of getting hot rad cap did not blow( brand new cap also). I did notice that the top rad hose was really hot and the bottom was not really hot at all? So do I have an air bubble or what? Not gonna drive it till I get some feedback. thanks
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If the top hose is hot, and the lower hose is cooler, then your radiator is working.
I might go to your parts store and buy a cheap 25 dollar temp gauge and use that. Or buy a laser style temp reader and read how hot the radiator is.
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There is no reason to run without a Tstat.
not saying its a bad ideal but when winter hits it will be bad since it wont warm up as much on newer cars its a can cause it to run rich but on ours right now theres no problem
OK so I just got a new fail safe tstat and put it in tried to keep the rad cap off for as long as possible then put it back on. The temp gauge said the truck was hot but I let it go for a few min longer cause it was just idling in the driveway. The hoses pressurized so the tstat must have opened. The only thing is its still saying the truck is running hot. If i start to drive at all it says hot, stop and it goes down a bit, truck showed no sign of getting hot rad cap did not blow( brand new cap also). I did notice that the top rad hose was really hot and the bottom was not really hot at all? So do I have an air bubble or what? Not gonna drive it till I get some feedback. thanks
whats hot to you and your gauge?
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the radiator should be fine it was working great when I ran it today without the tstat, not sure how hot is hot its on the factory gauge in the truck and the sender is brand new. It just gets into the red but if you shut it down or let it just idle it will go down a bit.
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with the rad cap off does the coolent just flow or are there allot of bubbles?
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I didn't look when I just did it with the tstat in, but this morning when I ran it without the tstat it was moving through the radiatior really well had a nice flow to it.
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are you using strait water?
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also you ran it at highway speeds with no tstat with no problem?
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got it up to 45 mph, this is the same rad I used with my 454 and never had any problems. No using a 50/50 mix of coolant and water.
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and what spped with the stat in till it over heats?
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It is almost hot just sitting in the driveway, take it out on the road maybe 20mph and the gauge says its hot? I dunno why its such a difference with the tstat in, the thing ran super cool without it, didnt even get up halfway on the gauge without the tstat.
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Thermostat is to maintain temp. (basically)
How's the fan and shroud? How accurate is the gauge?
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Ok here's what I think. Your Rad is restricted or the water pumps fan blades are worn causing inadequate flow its enough flow with out the thermostat. But the thermostat it self restricts flow so. Red that's flow is restricted + thermostat = over heat or worn water pump blades +thermostat = over heating. I would say flush the system try it then or flush it and add a new water pump. Does that make any sense what ever the problem is its not bad enough to cause over heating unless its restricted with the thermostat and when you idling you engine doesn't require allot of water and your probably flowing just enough to keep it cool
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Its a brand new water pump actually the second brand new one I have put on it in a week just to be sure. I almost think its an air bubble in the system, but how do I get it out? The coolant is ready to come out the fill hole on the rad by the time its hot enough to start circulating through and I cant really get the air out if its not circulating. God this truck stumps me all the time, I seriously think it likes to be in the driveway with the hood up more than it likes to be driven.
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Sometimes a loose fan belt can be the cause of cooling problems. Make sure there's no more than 1/2 " deflection in that belt. Also, a bad radiator cap can cause cooling problems. There's a small vacuum valve in them and if the valve fails then the system pressure won't be equalized. A hose can partially collapse and restrict coolant flow back to the radiator. When flow is restricted the system overheats.
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If you are draining everything just enough to do the t stat swap, then you wont have air bubble problems. A quick drive around will get rid of them. You will only have air pockets if you drain the block.
You first came here to discuss your broken temp gauge. What is the status of it. Do you trust it is working now?
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If you fill it like vile said through the thermostat house then once that's full put it I'm and fill the rest up through the Rad cap. I would then bet its a dirty rad
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The temp gauge is working not sure how well? Yes let just enought fluid out to do the tstat, I did fill it originally through the block. Just tightened up the fan wp belt and still same crap. It can sit and idle for like 3min and the gauge says it hot and overheating. The radiator on the sides it hot to the touch not super hot, but hot the cap is cool however. I don't get it, guys I will just let this one die I am sick of messing with it and putting money into it with no results. Thank you all for your help.
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Your radiator is hotter on the driver side because it is supposed to be. That is where the HOT water is coming in.
I would go buy a cheap temp gauge and set it up temporarily just to make sure your getting a correct reading.
http://sunpro.com/product_detail.php?pid=16323
What kind of fan do you have, and do you have a fan shroud?
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clutch fan, and shroud, the shroud is from the 454 so the fan is not totally inside but 95 % inside if u know what I mean. Might try the new temp gauge just have some much money in this thing I am going crazy, thanks man.
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same setup on the 454 never a problem, dam thing ran cool all the time.
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Wait it over heats at idle?
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Yep just sitting at idle it says its hot overheating?
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http://www.harborfreight.com/infrared-thermometer-93984.html
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Is the gauge bad?
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Well you came on here asking about your temp sensor and gauge. I would use a outside source to determine if the gauge, wiring, or sensor is faulty. Then you will know if the engine is getting too hot or not.
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Without a thermostat at idle its ok
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yea no tstat at idle the gauge was saying its fine
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That could be because it isnt getting a chance to warm up enough. How hot is it where you live? Is it staying cool in the driveway, or are you driving down the streets? Driving to the end of the block and back wont count.
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nope drove it alot with no tstat and she was fine, just put a new temp gauge on it and it says at idle its running about 200-205 degrees?
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is that with or without the stat
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you got a cheap temp gauge?
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With the tstat, that's what its running. Yea new guage
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whats it running at at highway speeds?
200 is a little high but it could be worse my truck is at about 170 idle and goes to 180 driving
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Did the gauge come with a new sending unit? What was the condition of the engine when you put it in, rebuilt?
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Motor was rebuilt 15 k ago I was told, I only had enough time to piut the gauge in last night no time to drive it. I was thinking maybe I should put in a 160 tstat?
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yea the gauge came with a new sending unit, I was thinking if I put the 160 degree tstat in it would probably run the truck about 180 or so, that would be better, any thoughts on that?
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ok drove it this morning, if you are barely on the gas it will stay about 200 get on the gas what so ever and the gauge climbs like a speedo, this is the new gauge by the way. On a flat I got on it some and the gauge almost hit 240 degrees. I feel like just going out and spending 2k and getting a crate motor and new radiator and throwing taking this pos up for scrap metal.
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It sounds like your radiator is working fine if it worked fine before the swap. Since it is a used engine, there is no telling.
Is it a 350? Get the casting number on the ridge above the oil filter. You have to look down behind the valve cover. I wonder if you got ripped off and it is a 400, which has a history of cooling issues. Just a thought.
Have you checked the oil to see if there is water/coolant mixed in?
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I wonder if someone used the wrong head gaskets...
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see im thinking the other way since it runs fine with out the stat in and with it in it hold the water back more causing more restriction and with a restricted rad it would cause it to over heat water in the oil wouldn’t cause it to over heat since if it was coming out the exhaust then yes it would over heat and since hes not losing antifreeze I don’t see that being likely. Also blow head gasket would bubble out once he took the cap off
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Nope its a 350, I was kinda mad after I bought it cause I found out it has the stupid 305 heads on it, but its a 350 2bolt main. Didn't see any oil in the coolant or any coolant in the oil or any foam under the breathers on the valve covers. So you guys think its the radiator, I am so stumped on this one and I just want to drive my truck so I'm willing to throw so money at the problem. If you guys think its the radiator then hey I will go buy a new 3 row alluminum tomorrow just wana drive my truck after all this work. Thanks guys, for everyone else sick of seeing this thread sorry just had to do it again :)
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I suppose it could be possible the 350 block dumped some crud into your radiator. Hate to see you dump $ for a new one. Maybe pull the radiator and flush it?
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Beastie, anything else I can check for a blown hg, I will flush it.
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I'd try rodding out the old one before I bought a new one.
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yeah test it while our at it also
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came home today to work on the truck and radiator is down about 1/3 of the way and I topped it off last time I ran it, tried flushing the heater core and it was fine hooked everything back up and topped the coolant off again. Ran the truck for 5 min and up to 210 degrees felt the hoses and they had very little pressure at all finally at 220 degrees they when I squeeze the top hose I can feel some coolant kinda surging through not a steady flow, but also not enough to really pressurize the hoses. Checked the exhaust and has a little white smoke, but wasn't sure if this is because the truck has only been running for 10-15 min probably about 45 degrees outside. Not totally sure but the exhaust on the pass side almost smelled a little sweet but not 100% sure what it should smell like if burning coolant. If I give the truck any gas the temp climbs really fast 230 or so. Is it the head gasket? I was driving it the day I noticed the cooling system was not working correctly. Has the 305 heads on should I just change them out for some decent rebuilt 350 heads how much work and how much $ will this be? Or should I just get another cheap 350 to get me by for now? Thanks
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it almost smells the same as coolant out of the bottle if you put a tester on it while its running the gas pressure would cause the reading to rise and you should see allot of bubbles in the rad while its running. Make sure since you saw it was 1/3 down that there’s no leaks in any connections or in the rad
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45 degrees out? You know its summer.....
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45 degrees out? You know its summer.....
was
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have not seen any bubble while its running. The coolant just sits there. Yesterday when I was running it the rad did get very hot on the drivers side and was cooler on the pass side, but why would it only do this with the tstat in, it flowed through the rad fine it seemed when there was no tstat in?
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FINALLY GOT IT, it was the dang heater core. Thing was leaking and I just sat there and filled the rad and it kept taking it and then I saw coolant coming from inside the cab. Blocked the heater core off and new 160 tstat new coolant took filled her up drove it and stayed right at 170. Got on it really hard once and it went to 210 then dropped super fast back to 170 and stayed there. Thanks for all the help. Now I just have a bad leak from the new oil pan and gasket at the back so sorry to say I will probably have a new thread in a day or two. Thanks again.
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