The other day a few times after parking from normal driving, I noticed a lot of coolant draining out. After my heart stopped pounding I realized it was only coming out of the over flow hose.

But I have not filled it up in a while so not sure why it was "overflowing" ???

Everything that came out was just water/coolant so no alarms there; ie no oil, milkshake, etc. No over heating, fans working fine, etc.

Any thoughts?

 

Pressureized coolant system, your headgasket is probably on the way to give in.

 

Pressure test the system. Every 944 owner should have one of these tools at their disposal:

 

Pressure test was done recently and held 15/16psi for 30 min and no drop.

 

Wouldn't there have been oil noticable in the coolant that driained out?

 

Other obvious thing to consider is that your pressure cap isn't holding pressure. Cheap and easy to replace.

 

Not necessarily.

 

After 15 years of owning Porsches I ALWAYS assume the worst first. LOL

So, thanks for reminding me to keep it simple first and then think worst case.

 

I'm with Duke on this one. Your headgasket is on it's way out. It's kinda acting like a check valve allowing combustion pressure into the coolant system but not leaking under coolant pressure.

 

See if it gets worse under a good hard driving session. If so, Duke is probably correct.

 

Yea, I will change the cap and then go do some boost runs and check again for drainage.

 

I'd pressure test it with the spark plugs pulled and check the cylinders for coolant before doing any hard boost applications. Last thing you want is to blow out the gasket and then have to deal with milkshake or worse.

You said it was pressure tested already, but was that before or after the coolant puke?

You could always bleed the system, take it for a short drive, then bleed it again. If there's air in the system the second time (and a pressure test shows no other leaks) then it's probably the HG.

FWIW, the exact same thing happened to me, and it turned out to be the head gasket beginning to fail.

 

Sidebar: Can the pressure testers also work on boost/vac leaks?

 

If there was a way to seal the system, sure. I can't think of one, however.

 

just thinking, but you COULD have a slight leak, in a hose somewhere, which should cause a similar symptom, right? If it's small enough, you may not see a puddle yet, because you are losing coolant when moving.
Am I wrong here?