Shop Porsche Head Gaskets

This isn't making much sense. How can the cooling system maintain pressure overnight? NOT. Compression is not so great. You mention rad cap releasing pressure - any coolant loss? Smell it? NO - you could test it for combustion gasses would be one of many tests.

If you just release pressure when cold. Feel a radiator hose or have a pressure tester on it. Be quick if using pressure tester and ready to release over pressure instantly and if pressure builds up fast not just expansion by warming up that is damning of combustion gasses getting into cooling system. Damning of head gasket or flaw with head perhaps which you really can't know without being there. If those two lower cylinder's pressure reading are abutting each other one may be leaking to the other via head gasket or metal flaw/crack.

You didn't say but it must be overheating? Head gasket highly likely IMO,

T

Did you pressure test the radiator cap to make sure it was venting off at the rated pressure?

Right on DS - test cap too. Any decent pressure tester will test caps too. Many can just be cleaned but the one little thing is quite important to the system. If I understand back a couple, then as said it really can't do anything but lose pressure when cooler as the coolant lost volume due to decrease in temp.

If going by just squeezing a hose and it still feels firm it may be the hose somehow got to be hard, most go softer with time,

T

no i had not tested the cap yet, i was looking into why there is always so much pressure in the cooling system, i will change that cap once i find the issue.

seems to me to be a head gasket issue but without the head gasket symptoms.

i am not overheating and has not overheated and to make sure the gauge was working correctly, i released the coolant and let the car run and it began to overheat, shut the car down, added the coolant back and bleed it and then started the car again and it would not overheat.

on the way home from work the other day i was getting fluid on my windshield and thought it was drizzling outside seeing it had rained and the road was wet so i turned my wipers on and looked around to see that no other vehicles on the road had their wipers on so i knew then it was coolant out of the cap coming back onto my windshield and have parked the car since trying to determine if it is the head gasket.

i am 95% sure it is but i am looking for other opinions or experiences similar to mine before i pull the block down.

i am no certified master mechanic but i can fix just about anything i need to including the head gasket but all the years i have been working on cars i have never seen this.

so my main theory as of right now is that exhaust is leaking through into the water jacket and pushing itself into my cooling system, what is your thoughts on this happening without the usual head gasket symptoms being shown ?

NO! Do not test overheating by letting coolant out - OMG! Sensor for car's gauge could be late if in air not liquid. Keep that up and YOU WILL need a head gasket even if not now.......

T

i never let it all out just enough to speed up the process, once the gauge hit above where it is supposed to be i cut the car off, i am not going to kill my car, i was just testing the gauge.

i will be tearing the block down tomorrow and looking into my head gasket and seals, valves and pistons, etc and will let you all know what the problem is.

i will be tearing the block down tomorrow and looking into my head gasket and seals, valves and pistons, etc and will let you all know what the problem is.

That's not how you find a problem. You do your testing before you take it apart.

Sport - Some common sense before you attack this thing to never run again. Look at your first post. Excessive pressure. How did you come to believe that? Again how could it hold that pressure overnight? NO.

Pressure testers that I'm familiar with if just left on a cold engine warming up do not release pressure by themselves if that's what you did. Perhaps some do? That would go as high as the system would allow and the weakest part would blow if just left on.

As Hammer just said. Do all you testing now as you can't know much more with it apart unless something is really obvious. If head does need to come off send it out to get checked anyway even if nothing seen by you,

T

usually when pressure builds up in the cooling system it is due to the coolant expanding, so after sitting overnight and cold to the touch the hoses should not be hard and the pressure should have released due to the coolant cooling and contracting to normal which it may or may not be doing, if it is then there is air/exhaust in the system coming from somewhere.

somehow air or exhaust is entering the cooling system, there is only 2 ways this can happen and either comes from a bad head gasket, to break the 2 ways down it is either exhaust or compressed air from the turbo, seeing boost is not what it used to be and i do not have a boost or exhaust leak visible on the exterior motor it has to be inside the block.

after doing a compression and a leak down test and coming to the conclusion compression is fine and it is iffy on the leak down there is either a bad head gasket, bent/stuck valve or bad piston rings.

since there is no white/black smoke it is hard to determine and the block has to be torn down.

i will test the radiator cap and thermostat but since i am not overheating and i know the temperature sender is working i have no other way to go but inside the block for examination.

hopefully it is just the gasket and the head itself is not cracked or warped, over a 100,000 miles and having the head milled usually ends up in disaster.

i can tell you this for a fact if it is the gasket then it just started and i caught it early enough to possibly have the head milled and not have to worry about issues in the bottom half of the motor due to improper compressions, etc.

usually when pressure builds up in the cooling system it is due to the coolant expanding, so after sitting overnight and cold to the touch the hoses should not be hard and the pressure should have released due to the coolant cooling and contracting to normal which it may or may not be doing, if it is then there is air/exhaust in the system coming from somewhere.

somehow air or exhaust is entering the cooling system, there is only 2 ways this can happen and either comes from a bad head gasket, to break the 2 ways down it is either exhaust or compressed air from the turbo, seeing boost is not what it used to be and i do not have a boost or exhaust leak visible on the exterior motor it has to be inside the block.

Your logic is because you think you have pressure holding overnight that you have a blown head gasket

Dude, you are lost here. Your logic is way out in left field. You need to let a professional look at this before you turn it into a pile of scrap steel.

i know my car and i can tell you that the hoses are rock hard and cannot be squeezed when the engine is at operating temperature and when cool should be somewhat squeezable.

when driving after a while there is fluid being blown up onto the windshield from the radiator cap.

this morning after the car has been sitting for 3 days the hoses were still rock hard and when i opened the radiator cap the fluid blew out of the radiator.

there is no question in my mind it has to do with air or something entering the system somewhere and the pressure is not easing off, there is no leaks, holes, tears, cracks in my hoses.

i have checked the coolant, the oil and the gearbox oil and none of it is mixing with each other, if i am lost and the 3 other opinions i have gotten are way out in left field then
asking another mechanic would do me no good seeing my brother-in-law is a mechanic and thinks it is head gasket or valve related.

i know this place is not a help hotline, i am merely using it for other opinions, so based on what i have mentioned what is your opinion tom and hammer ?

Thread now locked and is over a year old never mind another's thread and type of car. Please read rules to post and start your own thread with your own specifics not hijack another,


T

Coolant shouldn't be blowing out of the radiator cap onto your windshield. Even if the cap was blowing off excessive pressure, the pressure should be purging off into the overflow bottle. You might want to inspect the seal inside the cap and test your cap's pressure rating.

When you did your leak down check, was there any bubbles in the radiator?

We are ALL just volunteering our time for free - know that w no mal intent and nothing to gain.

Have you tested the pressure cap yet? How could you not be losing coolant if it can spray all over windshield? The holding pressure if really so for now up to 3 days seems impossible but I suppose since you released pressure after that time the cap can hold WAY too much pressure that even as engine cools off still hold some. THAT WILL USUALLY BLOW HOSES, WATER PUMP, RADIATOR OR HEATER CORE NOT A GASKET AND HAVE NEVER SEEN A CAP DO THAT EVER. That cap should be marked with it's pressure rating and testing it should let go by that #. If not toss that one. If your tester can't test it then just toss it as it's the regulator for cooling system pressure and release.

Can't know much more till that issue alone is fixed or known. If you take it apart you could still test the cap but no more system checking as already said,

T

Just a query mate, does your car has a factory fitted turbo.
Also if you fitted a turbo in it , the coolant will be at higher temperature and the radiator cap should be of high rated.

Just a query mate, does your car has a factory fitted turbo.
Also if you fitted a turbo in it , the coolant will be at higher temperature and the radiator cap should be of high rated.

OK, some more completely flawed logic

"usually when pressure builds up in the cooling system it is due to the coolant expanding, so after sitting overnight and cold to the touch the hoses should not be hard and the pressure should have released due to the coolant cooling and contracting to normal which it may or may not be doing, if it is then there is air/exhaust in the system coming from somewhere."

What on earth could be adding pressure overnight - please inform me of much of anything but water freezing that stays the same hot or cool/cold. I sqeeze hoses too if only to quick know that it's ok to remove a pressure cap. If it held overnight and you could realease pressure and hear it at the cap something I've never heard of is happening. That's unless someone sneaks out and is playing tricks on you. The hose could just be hard all the time for all I know.

This is the observation you began with. It doesn't overheat if full of coolant, no symtoms mentioned (sorry if I missed something now) except this excessive pressure. Probably if things are tight it would build up to ~ 15 PSI which does feel like a good bit of pressure - Normally. You certainly can drive a common tire on that much.

Seems not much is conclusive yet to me or flawed observations? - Tom

(just know we volunteer and not always on line waiting so don't think the site is some 911 call 24/7 so if no quick response wait or another jumps in)