[520]

Hey guys hows it going, Well one day my car overheated so i took it to Godspeed (now TuningFactory) and they ran a compression and leak test, Both came out fine. The car isnt over heating anymore but when i hit 12+ psi coolant is forced back into the resevoir and shoots everywhere in the engine bay and throught the hood cutouts onto my windsheild. It seems there is too much pressure built up in the system. Thats what Dan at godspeed said. I trust dan over 100% and he said that new radiator caps should do it. I just wanted some more opinions of what you gurus on here think.
Please dont flame this is just a question i have.
Thanks a lot
Amit

[XfactorSTi]

its tuff to say, but any time you over heat a aluminum engine you risk warping the head or the block which is bad, i believe you are the 16 year old with the mag car right? mayb you have a leak some were, just be sure to STOP the leak because any air in the cooling system can over time destroy your engine. built or not.

[siusti]

A new radiator cap should fix the problem. If it doesn't, then you have a mechanical issue.

[Flycaster]

That's a classic sign of a blown head-gasket which is a very common result of overheating. The best test is to have the coolant tested for hydrocarbons: if your gasket failed you will see combustion by-products in the antifreeze.

A "new radiator cap" will only mask the problem, if that's what it is, and it will lead to a blown engine if left unrepaired. Find a real mechanic (not a tuner) and get it fixed.

[520]

Originally Posted by Flycaster

That's a classic sign of a blown head-gasket. The best test is to have the coolant tested for hydrocarbons. If your gasket failed you will see combustion by-products in the antifreeze.

Find a real mechanic (not a tuner) and get it fixed.

Its not a blown head gasket, they tested for it.
I am hoping that the radiator cap should fix it. And they did not find any leaks.
Oh by the sometimes when i let off the gas the BOV goes off then i hear a rush of air. Is this just the wastegate or something else??
Thanks a lot for the quick replys
Amit

[Flycaster]

Originally Posted by 520hpSTi

Its not a blown head gasket, they tested for it.
I am hoping that the radiator cap should fix it. And they did not find any leaks.

Really? So what does Godspeed say has suddenly pressurized the radiator in a way that just happens to vary with the amount of cylinder pressure your engine is producing?

[520]

I honestly cant tell you what caused it. I sense some aggression in your post lol, not sure if it was meant to be there. Thanks for the input though. Also i drove it home about 130 miles but didnt really get on the boost much. Then i got on it the next day. It seems that when the coolant sprays out of the resevoir, a substantial amount is lost. Therefore i have to refill the coolant if it happens, this stops the overheating.

[Stee]

I would say that it was a defective thermostat. If it isn't opening, it would cause pressure buildup to everything before it causing it to seek exit via the radiator cap.

[520]

Originally Posted by Stee

I would say that it was a defective thermostat. If it isn't opening, it would cause pressure buildup to everything before it causing it to seek exit via the radiator cap.

I thought the exact same thing. Then i called Dan and he told me that i have a failsafe thermostat that only fails open.
Thanks though, maybe even the failsafe is defective.

[Flycaster]

Originally Posted by 520hpSTi

...I sense some aggression in your post lol, not sure if it was meant to be there...

Nope, just given the symptoms as you've stated them, nothing else makes any sense. What were your leakdown numbers and did you see them pull the radiator cap to check for fluid surge or bubbles when they pressurized each cylinder?

Try a new oem radiator cap - if it doesn't work, get someone else to run a leakdown.

Originally Posted by stee

I would say that it was a defective thermostat...

That would certainly cause the block to overheat, but not to pressurize the radiator; if the thermostat is frozen shut, the radiator is totally out of the loop. Remember, the kid says it is no longer overheating and that the loss varies with boost [cylinder pressure] - that's a dead give away for blow-by induced pressurization. It'd be the same thing if it were oil loss through the breather tubes, except it'd be the rings not the head-gasket.

[BoostJunkie]

this is why I would never buy a car that was heavily modded by someone else. It makes it tough to diagnose problems when you're not 100% sure what mods are on the car.

[520]

Originally Posted by Flycaster

Nope, just given the symptoms as you've stated them, nothing else makes any sense. What were your leakdown numbers and did you see them pull the radiator cap to check for fluid surge or bubbles when they pressurized each cylinder?

Try a new oem radiator cap - if it doesn't work, get someone else to run a leakdown.


That would certainly cause the block to overheat, but not to pressurize the radiator; if the thermostat is frozen shut, the radiator is totally out of the loop. Remember, the kid says it is no longer overheating and that the loss varies with boost [cylinder pressure] - that's a dead give away for blow-by induced pressurization. It'd be the same thing if it were oil loss through the breather tubes, except it'd be the rings not the head-gasket.

Thanks a bunch
I did not see them do it because they do all tests and work in the back and dont allow anyone in. But i trust Godspeed with 100 confidence

[Flycaster]

Originally Posted by 520hpSTi

But i trust Godspeed with 100 confidence

Since you keep repeating this, just pay him to "fix" it and we can kill this useless thread.

[reid-o]

This shouldn't be very hard to diagnose.
You just need to verify whether it's coolant flow or not.

This is fairly easy.
With the car nice and cool, open the radiator cap and let the car idle.
Wait till the car reaches operating temp.
You should be able to see the coolant "flow" through--a noticeable diffference between when the fluid was stagnant and when it's moving. If you see no water flow, you can suspect the water pump or thermostat.

If it's moving, then you can rule out water pump, and thermostat.
Next wait a bit longer and see if the fans come on. They should kick on with either the ac or when the car starts to reach 200ish--not sure what the kick on point is for Subarus, but this is a rough guideline. If your fans are not coming on, then you'd better check the sensors for failure.


If all of this checks out, then it may be your radiator cap. Replace that and try it out.
If everything checks out, and you can't figure it out what it is, I'd suspect headgasket.


Turbo cars are generally hard to diagnose when it comes to headgaskets. Compression checks and even leakdowns will generally show only really bad failures, when it's already pretty obvious. I've had cars with minor leaks before that checked out okay with even a leak down. But after full throttle runs, the car would "push" coolant. And there were days when I'd drive with no overheating. I'd pull the head and find a pinhole breach...very minor..but enough to pressurize the cooling system.


One sign unique ]of a headgasket breach on a turbo car is that you'll overheat particularly under boost, the exhaust gas working their way into the cooling jackets under extreme combustion chamber pressure.
Most people think headgasket leaks need to be catastrophic failures, oil and water mixing. This kind of breach is only for average cars that aren't maintained and where the owner doesnt know jack and just runs the car until it dies. It's common to have a leaking gasket hold most of the time.


One possible way to check the headgasket besides leak down is to check your plugs. If coolant is getting in the chamber, one plug should be way cleaner than the other. The real way I learned, but this doesn't apply to flat fours, is to stick a scope in the cylinder and see if one piston top is super clean.

[520]

Originally Posted by reid-o

This shouldn't be very hard to diagnose.
You just need to verify whether it's coolant flow or not.

This is fairly easy.
With the car nice and cool, open the radiator cap and let the car idle.
Wait till the car reaches operating temp.
You should be able to see the coolant "flow" through--a noticeable diffference between when the fluid was stagnant and when it's moving. If you see no water flow, you can suspect the water pump or thermostat.

If it's moving, then you can rule out water pump, and thermostat.
Next wait a bit longer and see if the fans come on. They should kick on with either the ac or when the car starts to reach 200ish--not sure what the kick on point is for Subarus, but this is a rough guideline. If your fans are not coming on, then you'd better check the sensors for failure.


If all of this checks out, then it may be your radiator cap. Replace that and try it out.
If everything checks out, and you can't figure it out what it is, I'd suspect headgasket.


Turbo cars are generally hard to diagnose when it comes to headgaskets. Compression checks and even leakdowns will generally show only really bad failures, when it's already pretty obvious. I've had cars with minor leaks before that checked out okay with even a leak down. But after full throttle runs, the car would "push" coolant. And there were days when I'd drive with no overheating. I'd pull the head and find a pinhole breach...very minor..but enough to pressurize the cooling system.


One sign unique ]of a headgasket breach on a turbo car is that you'll overheat particularly under boost, the exhaust gas working their way into the cooling jackets under extreme combustion chamber pressure.
Most people think headgasket leaks need to be catastrophic failures, oil and water mixing. This kind of breach is only for average cars that aren't maintained and where the owner doesnt know jack and just runs the car until it dies. It's common to have a leaking gasket hold most of the time.


One possible way to check the headgasket besides leak down is to check your plugs. If coolant is getting in the chamber, one plug should be way cleaner than the other. The real way I learned, but this doesn't apply to flat fours, is to stick a scope in the cylinder and see if one piston top is super clean.

Thanks alot man;very informative
Ill try that stuff tomorrow!
by chamber i am assuming you mean combustion chamber correct?
Well thanks alot
Amit