HELP!!!!! Overheating Issue!!!

90tbird4.7l

Registered User
My 90 SC keeps sucking air in from somewhere and i cant seen to find out where. I would have to warm it til it forced 1/2 to 1 gallon of coolant into the overflow (doesnt even let the thermostat open), shut it off, drain the overflow, refill the system and it was good to go til it sat for 6 or more hours (Otherwise I would have to do it all over again, big hassle!). The other day I noticed it was leaking from the T-stat housing, so yesterday i installed a new T-stat (made sure it was sealed up this time). It keeps sucking air into the motor causing it to blow the antifreeze into the overflow, practically emptying the radiator. Everything it sealed and I cant figure out where the air is coming from. Radiator cap is new. Car is my daily driver, 117,000-ish miles runs and idles fine, no signs of a blown head gasket. Is it possible for the pump to cause this issue? I am not losing any coolant, just cant keep it in the motor. Please help, if i cant get it fixed soon i will be forced to get rid of the car, and with it being my only car, i am kinda screwed.
 
Yes it's possible for a pump to suck air in try the weep hole and not leak.
I had the same problem your describing. It was te head gaskets. There was no oil mixing with coolant, or vise versa. It would just push enough air into the system to make it bubble and after driving it would push it out until it got really hot.
Pop the cap and see if it smells like exhaust gas.

I did a leak down test, replaced the thermostat, watched the fan kick on and off at right command temp, and even checked temps thru the radiator. All checked fine until it got super warm. Did a compression check. One cylinder had 70psi while all other on that bank had 100psi. The other bank was at 130psi.
 
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It's always possible that you have a slight manifold gasket leak and your getting boost into the coolant system.
I've seen that happen before.
 
My 90 SC keeps sucking air in from somewhere and i cant seen to find out where. I would have to warm it til it forced 1/2 to 1 gallon of coolant into the overflow (doesnt even let the thermostat open), shut it off, drain the overflow, refill the system and it was good to go til it sat for 6 or more hours (Otherwise I would have to do it all over again, big hassle!). The other day I noticed it was leaking from the T-stat housing, so yesterday i installed a new T-stat (made sure it was sealed up this time). It keeps sucking air into the motor causing it to blow the antifreeze into the overflow, practically emptying the radiator. Everything it sealed and I cant figure out where the air is coming from. Radiator cap is new. Car is my daily driver, 117,000-ish miles runs and idles fine, no signs of a blown head gasket. Is it possible for the pump to cause this issue? I am not losing any coolant, just cant keep it in the motor. Please help, if i cant get it fixed soon i will be forced to get rid of the car, and with it being my only car, i am kinda screwed.

Sounds exactly like a leaking head gasket allowing combustion gasses into the cooling system. When you say "no signs of a blown head gasket", what all have you checked to make that determination ?

Are you using MLS gaskets or the stock style composite gaskets ? Have you done a compression test ? Have you pulled the plugs ?

David
 
this is exactly what happens when a head gasket leaks

if its your daily force on the fan until you can get around to changing the head gaskets

costs about $450 all said and done, that includes getting the heads resurfaced
 
Its the hg's man Same thing mine did ! tear it down have the heads checked and milled ARP head studs felpro gaskets call it done. Don't use MLS unless you start with a fresh block deck surface!
 
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Remove the accessory belt so you can check the water pump pulley to see if the bearings are smooth with no play/wobble in any direction.

Mine ('90 w/100k) was weeping just a bit and overflow tank was doing the same as yours - finally got around to replacing the water pump and the overflow tank drama went away.

Be sure to use a new/good condition straight 16# cap. Don't be afraid to add some cooling system leak sealer when you put it back together. Consider adding Water Wetter as part of the job.
 
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Don't be afraid to add some cooling system leak sealer when you put it back together.

I don't know that I would use any leak sealer. It gums up heater cores and coolers after time, as well as coolant passages in the block.
I know, some people claim that they never have any troubles after they put it in. But, once you've pulled a heater core out because the costumer complained of poor heating and theyve told you that they put sealer in the system and you go pull the heater core and its gummed up to about an 1/8" hole to allow coolant to enter and exit, thats enough for me to NOT put it in my personal cars. They ended up paying for a head gasket job and a heater core job.....$2400 later and they are good, but that could have been a $1200 job if they wouldnt hve bad-aided the problem. Also, when sealer has been ran thru the coolant passages in the block, it does the same thing at the head gaskets, sometimes compleltly blocked.
To me it's not worth using just to band aid a problem that needs to be addressed, and why make more work for yourself later down the road.
 
I don't know that I would use any leak sealer.

If the practice is good enough for the factory, its ok with me. Just be picky about what you use, of course.
 
I know this is a long running debate, I just was curious as to what you meant by the "if the practice is good enough for factory" thing. That's what I was wondering about.
 
I know this is a long running debate, I just was curious as to what you meant by the "if the practice is good enough for factory" thing. That's what I was wondering about.

Bar's Leak has been installed at the factory in recent vehicles from several different OEMs.
 
Bar's Leak has been installed at the factory in recent vehicles from several different OEMs.



I was unaware of this. I have heard about it, and some customers have asked/told me about this, but the Ford rep that came to the dealership a couple months ago confirmed this was not the case. But, who knows.
 
I was unaware of this. I have heard about it, and some customers have asked/told me about this, but the Ford rep that came to the dealership a couple months ago confirmed this was not the case. But, who knows.

They may not be adding to vehicles right now, but I am pretty sure they did a few years ago. Same with GM.

Also, there are a couple of "flavors" of the stuff. The powdered ginger one may have less risk than the "aluminum" one, but I don't know.
 
Update: head gasket is blown, luckly it will only cost about $120 to fix. Thanks all for your replies.

At a minimum, you will need to resurface the heads and buy a new set of head bolts or some head studs, because the original Torque to Yield bolts are not reusable. Plan on replacing the motor oil and engine coolant too.

David
 
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