What causes high cooling system pressure?

KpSupra

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The upper and lower hose pressure is such that I cannot squeeze them even a little bit when the car is running, or even a good while after it is shut off. I have coolant leaks appear in a different place every week. Could it be the head gasket? I had the block decked and the head checked out before they installed the HKS metal head gasket.
 

TooGoode

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The upper and lower hose pressure is such that I cannot squeeze them even a little bit when the car is running, or even a good while after it is shut off. I have coolant leaks appear in a different place every week. Could it be the head gasket? I had the block decked and the head checked out before they installed the HKS metal head gasket.
there is a decent possibility that the mhg did not seal properly and is letting some exhaust gasses into your colling system and creating more pressure than normal....i would suggest a leakdown test...
 

figgie

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nope

the cooling system is infact pressurized. What happens is that you take a 17 year old car that has never had hoses replaced, add some normal pressure of the cooling system, insta-broken hoses.
 

black89t

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high as in pouring out the overflow or what you think is high by feeling a hose?

if the pressure isn't getting high enough to pour out the overflow i doubt his hg is leaking. i have seen some old hoses that bulge and look all haggard like the shit is going to pop. then with a new hose that isn't worn and thin it holds its shape and doesn't appear as if there is to much pressure in the system.
 

KpSupra

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I'll look at all these. I took it to the shop with no leaks after the rebuild to let them look at it. Immediately after I got it back, the water pump, the metal tubing flange that bolts to the back of the thermostat housing and the turbo hose were leaking. Fixed all those and a coolant line that goes to the throttle body started leaking. Fixed that and the lower radiator hose started leaking. The radiator hose doesn't start leaking until about 3 minutes after the engine is shut off, (after a one minute cool down idle). It also leaked the same with no thermostat.
 

j3pz

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sounds like old/inadequate hardware. check your radiator cap also to see what kind of condition it is in and nothing is keeping it from opening/closing. i was having problems with my cooling system. upon noticing my cap was in bad shape, i replaced it and alot of my cooling/over flowing problems went away.
 

cjsupra90

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^^^^ Im surprised that no one has said the cap yet until now.... That would be my first suspect if pressure is extremely high being as how the cap is what controls the pressure.....

I'd even more suspect the cap being that it seems as though there is a lot of old equipment and also the fact that the radiator hose leak started after the car was shut down for a few minutes....

If the head gasket was leaking, the pressure would drop pretty quick once the car was turned off but insted cause of leaking back into the cylinder, but insted it increased which is normal (so to speak).. Here is why, when you shut a car off, for the first 5 minutes or so of no coolant flow, the coolant temp increases in the engine. As most know, as it heats up, it expands well if there is no room for expansion to accure, then it increases pressure.. The cap regulates pressure by bleeding off the pressure and created form the expansion to the coolant overflow bottle.... If the cap cant relieve the pressure, then something has to give, thus leaks form..