Darwantae951

Hey guys,

Here's what's happening. Whenever I drive my car and don't get on boost, everything is fine. It's only when I hit boost a few times that this starts happening. I always let the car cool down if I hit the boost, but it always seems to push coolant out of the overflow tube...and I don't know why. Like I said, if I don't get on it at all, it doesn't do it. Last time I had the expansion tank cap off, part of the rubber lip broke...and it only started happening after that. My worst fear is my head gasket is starting to go and it's pressurizing the cooling system. Any ideas? I don't burn any coolant and have no white smoke coming from my exhaust.

-Darwin

cb951

I assume you replaced the damaged cap?

Running harder, especially on boost, causes the engine to run hotter and, thereby, at greater pressure. If the cap seal is damaged, it may not hold the pressure as well. Loss of pressure will cause higher temps yet. You'd likely lose coolant through the overflow.

Darwantae951

Currently waiting on a new cap, so can't rule that out yet. I hope that solves everything tho. I have an 84 944 I can borrow the cap from, are they the same?

-Darwin

89951DREAMER

Dude, sounds to me like you have a bad headgasket. There are a couple of ways to diagnose this. One is a leakdown test which pressurizes a cylinder at tdc. This is used to diagnose valve, ring, piston, and headgasket problems. The other way of testing is called a block test. This consists of a liquid that is poured into a device that goes onto the expansion tank. The engine is run with this device installed, and any combustion gasses that are in the coolant system will change the color of the liquid. The color change would indicate a combustion leak into the cooling system. Either of these tests would be the first thing I would do if it were my car. Good luck.

Ian

Darwantae951

Thanks Ian, where do you buy these things for a block test?

-Darwin

89951DREAMER

The shop I used to work at had one. I'll see if I can find out exactly what it was and PM you.

Ian

cb951

According to the Porsche PET, the later cars use #944 106 257 00, while the early cars use #928 106 257 03, so the caps are not the same.

I think a damaged cap seal would definitely cause the problem you're having. Try a new cap first. If that's not it, then Ian's suggestions might be the next step.

89951DREAMER

I found the block test kit at NAPA auto parts.

http://www.napaonline.com/MasterPage...f+Engine+Block

Ian

RKD in OKC

I replaced my cap when that was happening and about 6 months later I lost the head gasket.

Darwantae951

I hate you...(jk)

Thanks for all the input guys, first will be a new cap, but if it still does it then I'll get the block tester. Thanks for all the input! (even you RKD...)

BTW RKD, when you replaced the cap (and before you totally lost the HG) did it stop pissing everywhere for a while?

-Darwin

Tom M'Guinn

Have you read the diagnostic portion of my head gasket write-up (linked below)? Are you still mixing oil and coolant after the oil seal replacement?

Chris Prack

I doubt you have a blown headgasket.

Replace or remove the turbo thermostat in the water pump. I can promise you it's broken or stuck shut. It won't allow coolant flow through the turbo so the water that is in there overheats and vents out the overflow. I have seen this a thousand times.

Easy repair.

Loquat15

A headgasket isn't the end of the workd if thats what it is.

A bad cap will cause this issue you're having, but a bad headgasket would do the same.

Just keep your head up high and if it's a headgasket, i hope you've done one before or have someone around that's done one before.

Reguardless of all this, maintain your cars life, whatever you do :-)

Darwantae951

Oil and coolant were never mixing, just had a really nice leak coming from the housing. It's been dry ever since!

The turbo thermostat in my car is brand new. Not even half a year old, do you seriously think that could be the culprit?

I'm not afraid to do a head gasket job, I just don't want to do it out here in Cali (I get out of the military in 6 months).Between my dad and myself, we've done many MANY head gaskets!

Thanks for all the input guys!

-Darwin

Chris Prack

Yes I do. EVERY time I have had a 951 that did not run hot, had no leaks, was fine under normal driving but puked a couple of quarts of coolant after say a 20 minutes session on the track (or being run hard on the street); that little t-stat was the culprit.

Did you possibly install it backwards? I have seen that quite often as well. It fits inside the plastic cap, it does not go into the pump.

Try removing it and see if the problem goes away. You can do this in about 15 minutes or less.