Need HELP
Drifting
Joined: Aug 2006
Posts: 1,624
Likes: 2
From: Canandaigua New York
You can also lay on the ground in front of the car and check up inside the air scoop.
I have to pull leaves out of mine every year.
If you haven't checked the thermostat lately, I would do that too.
If might be sticking.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
If the 280 is with the air on, ....don't turn it on till you get this fixed.
first of all, open the radiator cap, and look inside. if the water level is low, ad either antifreeze or water for this phase. do not replace the cap just yet.
start the car and watch the temp climb. when the temp gets to approx. 170, go out and look at the water in the radiator cap hole.
the water will start to circulate, and the level will rise.
If the water does not circulate, put the cap back on, and shut it off.
If the water level circulates, have the antifreeze handy, raise the RPM of the car by moving the underhood throttle, and watch the water level drop down up to about 2 inches. with your free hand, add water to the radiator.
Before you let go of the throttle, put the cap back on. then let go of the throttle.
drive the car, don't let it get over 250.
Oh, by the way, did you just change the lower radiator hose? does it have a spring in it? If it doesn't, the hose may b collapsing when the pump is sucking water into it.
first of all, open the radiator cap, and look inside. if the water level is low, ad either antifreeze or water for this phase. do not replace the cap just yet.
start the car and watch the temp climb. when the temp gets to approx. 170, go out and look at the water in the radiator cap hole.
the water will start to circulate, and the level will rise.
If the water does not circulate, put the cap back on, and shut it off.
If the water level circulates, have the antifreeze handy, raise the RPM of the car by moving the underhood throttle, and watch the water level drop down up to about 2 inches. with your free hand, add water to the radiator.
Before you let go of the throttle, put the cap back on. then let go of the throttle.
drive the car, don't let it get over 250.
Oh, by the way, did you just change the lower radiator hose? does it have a spring in it? If it doesn't, the hose may b collapsing when the pump is sucking water into it.
Last edited by coupeguy2001; Oct 7, 2012 at 11:15 AM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
How long does it take to get to those temperatures? Does it do it all the time or only under certain conditions? The thermostat could be stuck closed.
You belt tensioner could be defective/worn. The belt could be stretched. <-- Maybe the belt is slipping on the water pump pulley.
Could be air in the system. Is the radiator full of water?
Is the radiator cap in good condition?
Overflow tank full of water?
You belt tensioner could be defective/worn. The belt could be stretched. <-- Maybe the belt is slipping on the water pump pulley.
Could be air in the system. Is the radiator full of water?
Is the radiator cap in good condition?
Overflow tank full of water?
Last edited by Cliff Harris; Oct 7, 2012 at 11:05 PM.
Thread Starter
2nd Gear
Joined: Sep 2012
Posts: 2
Likes: 0
From: Miami FL
The radiator is full to the cap.
I had the car running a couple of days ago, with the cap off
and the water looked like it wasn't circulating, it was actually
spilling out of the inlet of the radiator cap, when I would rev the idle
from the front.
I had the car running a couple of days ago, with the cap off
and the water looked like it wasn't circulating, it was actually
spilling out of the inlet of the radiator cap, when I would rev the idle
from the front.
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Drifting
Joined: Feb 2008
Posts: 1,535
Likes: 177
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
let it run until hot with cap off. It should circulate when it gets to 199*. If not your thermostst is stuck. Time to replace.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You have a stuck closed thermostat. Replace your thermostat. You get air out of the cooling system by removing the filler cap, warm engine until thermostat opens and race the engine slightly which will make the coolant drop out of sight and fill the radiator, put the cap on and let the engine back down to idle.
Safety Car
Joined: Aug 2009
Posts: 3,745
Likes: 275
From: Melbourne, Victoria, Australia
I agree that your t/stat could be dead 
Put it in a pot of water and see if it opens before the water boils, they are cheap just replace it with a 190F one i think that is the standard one.
Also the temperature sender i have had them go bad after overheating them (but never to 280 f it will be toast for sure) they will show way higher than actual, the oil temp should be within 10 to 15 deg of the coolant temp so see how it tracks with that.
The engine temperature sender is on the driver side, on the cylinder head between cylinder 1 and 3(has a flat spade terminal)
With the cap of the water should only flow when at operating temperature, then rev it (water level should drop a bit)to top it up and replace the cap.
Put it in a pot of water and see if it opens before the water boils, they are cheap just replace it with a 190F one i think that is the standard one.
Also the temperature sender i have had them go bad after overheating them (but never to 280 f
it will be toast for sure) they will show way higher than actual, the oil temp should be within 10 to 15 deg of the coolant temp so see how it tracks with that. The engine temperature sender is on the driver side, on the cylinder head between cylinder 1 and 3(has a flat spade terminal)
With the cap of the water should only flow when at operating temperature, then rev it (water level should drop a bit)to top it up and replace the cap.
Last edited by gerardvg; Oct 9, 2012 at 12:05 AM. Reason: More info
Drifting
Joined: Aug 2006
Posts: 1,624
Likes: 2
From: Canandaigua New York
In the case of a possible stuck thermostat, the simplest thing to do is to pull it out and run the car without it.. If the temps drop drastically, then the thermostat was your problem.
If not, then you've got much bigger issues.
If not, then you've got much bigger issues.
Drifting
Joined: Feb 2008
Posts: 1,535
Likes: 177
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
If you go that far just put a new one in. You won't have to tear it apart again.
Drifting
Joined: Aug 2006
Posts: 1,624
Likes: 2
From: Canandaigua New York
What happens if you put a new one back in and it still over heats?
Not the thermostat. You just replaced it... right?
Actually, I've had two (2) new aftermarket thermostats that were stuck closed, right out of the box.
Luckily, I run and Edelbrock intake and thermostat housing that uses a rubber o-ring seal.
5 minute change and no gaskets or sealer to buy.
Besides, the idea of removing the thermostat is to verify the coolant flow.
With a thermostat in place, you have to wait for it to open to check the flow and by then it may be getting too hot and coolant could blow out when you remove the radiator cap.
I'd rather remove the thermostat and then check for flow on a 'cold' engine, rather than a hot one.
But, that's just me...
Drifting
Joined: Feb 2008
Posts: 1,535
Likes: 177
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
True to a point.
What happens if you put a new one back in and it still over heats?
Not the thermostat. You just replaced it... right?
Actually, I've had two (2) new aftermarket thermostats that were stuck closed, right out of the box.
Luckily, I run and Edelbrock intake and thermostat housing that uses a rubber o-ring seal.
5 minute change and no gaskets or sealer to buy.
Besides, the idea of removing the thermostat is to verify the coolant flow.
With a thermostat in place, you have to wait for it to open to check the flow and by then it may be getting too hot and coolant could blow out when you remove the radiator cap.
I'd rather remove the thermostat and then check for flow on a 'cold' engine, rather than a hot one.
But, that's just me...
What happens if you put a new one back in and it still over heats?
Not the thermostat. You just replaced it... right?
Actually, I've had two (2) new aftermarket thermostats that were stuck closed, right out of the box.
Luckily, I run and Edelbrock intake and thermostat housing that uses a rubber o-ring seal.
5 minute change and no gaskets or sealer to buy.
Besides, the idea of removing the thermostat is to verify the coolant flow.
With a thermostat in place, you have to wait for it to open to check the flow and by then it may be getting too hot and coolant could blow out when you remove the radiator cap.
I'd rather remove the thermostat and then check for flow on a 'cold' engine, rather than a hot one.
But, that's just me...
Leave the cap off and just watch to see the flow. If you loose fluid step up idle and top off. You are going to need to top off hot anyway. Probably 15 more ways to do the same. Nothing wrong with your way.
Le Mans Master
Joined: Jul 2004
Posts: 6,213
Likes: 694
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Definitely change the thermostat first.
If it still gets too hot your radiator probably looks like mine did. Get it out and clean it up.
Safety Car
Joined: Aug 2009
Posts: 3,745
Likes: 275
From: Melbourne, Victoria, Australia
When you have cleaned between your radiator and a/c condenser put a mesh screen to stop it happening again
You slide a mesh in between the X frame and in front of the air filter as i have done on mine,
or buy a one with instructions from ebay
http://www.ebay.com/itm/84-91-CORVET...&forceRpt=true
http://www.ebay.com/itm/91-96-CORVET...&forceRpt=true
Last edited by gerardvg; Oct 13, 2012 at 08:10 AM.