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Thread: Overheating

  1. #1
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    Overheating

    So what's the best way to figure out if the water pump is gone? And is there a way to check the thermostat without having to pull it? I guess I can pull the thermostat to determine if that is the problem, but I'm not sure if there is a way to check the pump. All I know is that if I pop the radiator cap and let the car heat up I don't see any flow in the top of the radiator. I know it isn't the fans because they are working just fine.

  2. #2
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    Ira, when the car warms up from cold and then hits your installed Thermostat temp, do you see the gauge temporarily drop or pause? With a decent gauge you can usually see the Thermostat open.
    Making woosh sounds since 2010!

  3. #3
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    The water pump is mechanical. It can't not work (ok well *nearly* impossible for it to not work). If it was bad it would be pissing coolant all over the place. Coolant can't move until the thermostat opens. Close the cap and let it run until the gauge starts to move. You'll be able to feel the radiator get warm starting with the top first, then the bottom. If it's getting hot and no coolant flow into the radiator, then you have air pockets in the system. Pop the lever on the cap and let the bubbles out into the overflow tank. Then monitor the overflow tank and make sure it always stays at least half full. The fans will come on when it gets up to temp and when the fans come on the thermostat will already be open and the radiator will be hot.
    Last edited by XR7 Dave; 06-07-2017 at 07:25 AM.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  4. #4
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    Quote Originally Posted by XR7 Dave View Post
    The water pump is mechanical. It can't not work (ok well *nearly* impossible for it to not work).
    You mean like the one we (the stepson and I) pulled from a Taurus, that had about 1/2 of one of the vanes left, due to previous owners not taking care of the cooling system properly?

    RwP

  5. #5
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    Quote Originally Posted by XR7 Dave View Post
    The water pump is mechanical. It can't not work (ok well *nearly* impossible for it to not work). If it was bad it would be pissing coolant all over the place. Coolant can't move until the thermostat opens. Close the cap and let it run until the gauge starts to move. You'll be able to feel the radiator get warm starting with the top first, then the bottom. If it's getting hot and no coolant flow into the radiator, then you have air pockets in the system. Pop the lever on the cap and let the bubbles out into the overflow tank. Then monitor the overflow tank and make sure it always stays at least half full. The fans will come on when it gets up to temp and when the fans come on the thermostat will already be open and the radiator will be hot.
    Well I don't know what to make of this. Started the engine with the radiator cap on. When the temp gauge started to move I felt the radiator and it was starting to get warm on the left hand side, so I cracked the lever on the cap. The engine warmed up to 195 when the fans turned on and the temp continued up to about 210-ish. At that point coolant began to flow out of the overflow tank. It held temperature at idle, all the while the coolant was at the top of the overflow, sometimes coming out sometimes not. I let it idle for a good 20 minutes but there was no change. At that point I closed the radiator lever and more coolant flowed out of the overflow. But it did hold temperature at 210-ish. Before I shut it down I turned the heater on high and the temperature very slowly went down by about 8 degrees.

    I shut it off, let it sit for about an hour and then started it up again with the system closed. Temp gauge went straight up to 220 and was climbing when I shut it off. I am at a loss. Did I not let it bleed long enough? If it was holding temp that long in the first place, and then it responded to me turning the heater on, I have to think that water was flowing, right? Should I have been pouring coolant directly into the radiator when it was flowing out of the overflow tank as if I was flushing the system? What am I missing?

    Maybe I should just open the bottom valve on the radiator and flush the entire system.

  6. #6
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    >Maybe I should just open the bottom valve on the radiator and flush the entire system.

    I would do that and pull both radiator hoses flush there as well. Dirty system can then be checked off the suspect list.
    Creighton
    Last edited by Creighton; 06-07-2017 at 09:46 PM.

  7. #7
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    Quote Originally Posted by Ira R. View Post
    So what's the best way to figure out if the water pump is gone? And is there a way to check the thermostat without having to pull it? I guess I can pull the thermostat to determine if that is the problem, but I'm not sure if there is a way to check the pump..
    The best way to check a thermostat in place is with an IR temp gun.

    Quick test on the water pump is to look at the weep hole under the snout to see if it's wet - seal/bearings are shot if so. That, and does the shaft rock w/the belt removed. I think these pumps are pretty stout tho, and yes, if the vanes are gone from corrosion, it might not as well be there.

    As for flow at the neck, you might have a hard time seeing action without significant RPM. I'd leave the cap on and use the temp gun to survey the thermostat housing, hoses and radiator tank(s), instead.

    I'd plan on a fresh thermostat and radiator cap, unless they're new recently...not a big fan of the lever type for the SC, tho. Get a straight 16# cap, not one that is rated from 13 ~ 16, as an example.

    Be sure to use the coolant bleed standoff when filling, and a couple decent drives to be sure all air is purged. Watch the upper hose to confirm it hardens up when the engine is up to temp, and stays that way for a while until the engine cools. Check to confirm it doesn't go negative and collapse after the car sits over night, as an example. If it does, check the tube to the expansion tank.

    Shine a light thru the radiator core to confirm it's not junked up. Blow it out w/compressed air from the rear to be sure.

    Ken

  8. #8
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    In my 94 SC (and I haven't worked to resolve this yet) it will overheat in the summer unless I turn on some sort of A/C or heat. Either way climate control must be on or the fan behind the rad will not turn. Before I realized this I would have my temp gauge at about 3/4 of the way to max. I know that's not a scientific measurement but when I first got the car it never got past half. Now that I run the system on lowest fan before auto and any temp it is fine.

  9. #9
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    Quote Originally Posted by Ira R. View Post
    So what's the best way to figure out if the water pump is gone?
    They usually leak a lot.. you can also test them by taking the serp belt off and turning it by hand to feel for any hitchs, or grinding, rough spots, or wobbling.

  10. #10
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    Most of you may not know many details about Ira's car, but the water pump, thermostat, radiator, rad cap, etc. are all pretty new. The entire engine was recently rebuilt with MLS headgaskets etc. and it does not have any crap in the cooling system. It does have an MP FMIC and aftermarket fans, pusher and puller, both wired together to come on at about 190 deg. and everything working as designed/intended. At least that is how it left my shop.

    Since then something went wrong with the fan wiring resulting in the fans not working and the engine (possibly) severely overheated. The car was limped around with botched fan wiring for some time before they were rewired. AFAIK they are still controlled by the EEC and should both come on at 190 deg. The car has a 180 deg thermostat. The lever cap is a 16lb version and is recommended for ease of purging air from a hot engine.

    Being that in my work we open/drain/refill/purge SC cooling systems on customer cars daily/weekly/monthly for various reasons, we use the lever cap to effectively remove air from the system quickly and with confidence. Obviously you don't need one and yes, they can leak after time so if you prefer to install a standard cap later, so be it, no harm no foul.

    Anyway, I have never recommended to anyone to actually run the engine with the lever up. Doing so just prevents the system from being able to develop pressure and will actually cause air pockets due to premature coolant boiling. I also never recommend letting a high performance engine of any type sit and idle for 20 minutes at a time. Drive the damn thing! Extended idling is not good for any engine, but WORSE for a high performance one.

    And maybe go buy a bigger radiator. The new extra high capacity Griffin wouldn't be a bad investment.

    And lastly, make SURE the fans aren't fighting each other.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  11. #11
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    Quote Originally Posted by Ira R. View Post
    Well I don't know what to make of this. Started the engine with the radiator cap on. When the temp gauge started to move I felt the radiator and it was starting to get warm on the left hand side, so I cracked the lever on the cap. The engine warmed up to 195 when the fans turned on and the temp continued up to about 210-ish. At that point coolant began to flow out of the overflow tank. It held temperature at idle, all the while the coolant was at the top of the overflow, sometimes coming out sometimes not. I let it idle for a good 20 minutes but there was no change. At that point I closed the radiator lever and more coolant flowed out of the overflow. But it did hold temperature at 210-ish. Before I shut it down I turned the heater on high and the temperature very slowly went down by about 8 degrees.

    I shut it off, let it sit for about an hour and then started it up again with the system closed. Temp gauge went straight up to 220 and was climbing when I shut it off. I am at a loss. Did I not let it bleed long enough? If it was holding temp that long in the first place, and then it responded to me turning the heater on, I have to think that water was flowing, right? Should I have been pouring coolant directly into the radiator when it was flowing out of the overflow tank as if I was flushing the system? What am I missing?

    Maybe I should just open the bottom valve on the radiator and flush the entire system.
    Did you observe the temperature gauge pausing at 180F like Corey mentioned? It should heat up to 180F fairly quickly, hang out there for at least a few of minutes, possibly rise to 190F-ish, then drop back down to 180F once the fans kick one (based on Dave's description)....mine is set-up the same way.

    If it heats up and blows right past 180F, I would suspect the thermostat is not opening properly/completely.
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  12. #12
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    Quote Originally Posted by DrFishbone View Post
    Did you observe the temperature gauge pausing at 180F like Corey mentioned? It should heat up to 180F fairly quickly, hang out there for at least a few of minutes, possibly rise to 190F-ish, then drop back down to 180F once the fans kick one (based on Dave's description)....mine is set-up the same way.

    If it heats up and blows right past 180F, I would suspect the thermostat is not opening properly/completely.
    That is, I suspect what we are dealing with here. But I have not been able to get a good look at it this way. Between my eyes and the gauge, I don't trust either.

    As far as everything else is concerned, the two fans are back online, wired up to come on together which they do, pulling or pushing in the correct direction. This has all been confirmed. It's hard to know exactly when they come on because I didn't hook up the computer during this and the gauge is somewhere between 10-12 degrees low, depending on where in the temperature range the engine is running. But my best guess was about 195, and I reported it as such.

    As far as the other comments are concerned, I was doing my best to follow the suggestions of the engine builder. Perhaps I misunderstood the instruction to
    Pop the lever on the cap and let the bubbles out into the overflow tank.
    Which is why, after doing all of this we took the car out on the road, with the results as reported above. The odd thing is that before we hooked up the pusher fan again, when the engine was running on the radiator fan only, this was not a significant problem. Engine ran fine, although a little hotter than I would like with the a/c on, and better the higher the rpms. But as soon as we wired up the pusher fan and startd driving the car again it started running hot and now, even if I pull the power to the pusher fan relay and run it on the radiator fan alone again, it gets hot.

    This weekend I think I'm going to grab a hose, open the radiator and run the engine at a higher rpm to see if I can determine if the water is flowing through the radiator. If it isn't, I have to presume that the thermostat froze, because nothing else makes any sense.
    Last edited by Ira R.; 06-08-2017 at 03:51 PM.

  13. #13
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    how old is that rad??

    If you have a rad that is starting to go south it will not do the job of cooling anything. Also if the fins are coming loose they will not transfer any heat or very little making it get hot.
    Now how to check your thermostat... this is simple, hang it in a pot on the stove,get your wife's cooking thermometer and start to cook the water in the pot. watch when the thing starts to open.. then you know if it is good or not??? Good luck....Rich
    Too many cars,too little time to drive them. Anything less than 500 cubes is a small block. If you slow down in life you will get run over..

  14. #14
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    water pumps do fail.... all the time..

    not just from leaking, but from falling apart.. the fins do come off them for two reasons.. The first is they get eaten away from lack of service, this could have been from before the engine was rebuilt. The second one is even worse.. bad parts when they were rebuilt.. This will make parts of the fins come off and travel thru the system blocking the water as they go.. I have seen this happen, but it is not a normal issue.. just food for someone to work with here.....Rich
    Too many cars,too little time to drive them. Anything less than 500 cubes is a small block. If you slow down in life you will get run over..

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