Nahpets

Hello!

Ive discovered that my coolant finds its way to the oil circuit. My car had been standing for 6 months and the reservoir was empty.
I found 1,5 litres of coolant found in the pan before starting the engine in order to move it.

Engine ran very well, coolant temperature was OK during driving and idling, no (visible) oil in coolant. And I let it run for quite some time, driving almost 100 km.

When I drained the coolant from engine there was no (visible) oil.

So it´s confusing ... just having the car standing, coolant finds its way into the oil, ending up in the oil pan. Not good...

In general what could cause this issue?
Checking the head gasket sounds like one way to go, but before going there what could be other possible leaks?
(I hope not a defect engine block or similar ...)

Look forward to any advise!

Cheers
Stephan

huskerick1

head gasket

Tom M'Guinn

If that much (most) coolant is just draining into the oil pan when the motor sits for extended periods, then you might also check/change the oil thermostat seals (aka oil seals, oil cooler housing seals) on the side of the block. They are lower in the system and would allow more of the coolant to drain into the pan versus the head gasket. There's a write-up on changing these seals (and the HG) in the link at the bottom of this post.

Nahpets

This has struck my mind, but the car runs very well and no smoke. No coolant consumption during driving, coolant temperature fine and I drive pretty hard. Use my car 90% for trackdays.

If the head gasket would be bad, it should be two ways then so during engine operation, oil should enter coolant circuit (no oil in coolant). But this isnt the case.
What do you think?

Nahpets

Thanks,
but this doesnt apply on my Turbo engine if I understand it correct.
I have an external oil cooler (as all turbos), thus the gaskets in the oil filter housing in the engine block is purely for oil lines. The N/As has a heat exchanger in the oil filter housing with water and oil lines/passages.
Or did I miss anything?

... even bought the gasket replacement kit to find the hard way .
Below images from my engine. Top is engine block. Bottom is the filter housing.

Nahpets

Latest news I have from a (very) experienced 944 mechanic is that there is a crack in the engine block where water cant meet pressurized oil.
This would be on the bottom of the block.

During driving, the crack closes.
When "resting" crack opens....


Does anyone have/know of pictures of an opened engine block where you can see it from above and below?

huskerick1

I was in the process of dwelling on this when I read the note about the cracked block, which sounds totally plausible. This would also explain why the coolant is not being burned in the combustion chambers and lack of white smoke.

Tom M'Guinn

Check out the oil seal replacement procedure in the link below this post. Even though the oil cooler is external, there are still seals that need to be replaced to prevent oil and water from mixing. You need new o-rings on both sides of the small aluminum pipe shown in your second picture. A cracked block is always possible, but significantly less common than bad oil seals.

Nahpets

Hi again,

thanks for your input both of you.

Ive checked your link for the replacement.
Im just about to reassemble everything with new seals. Thanks for the link(s)!

I pray that this will do the trick ...

Thanks!

Nahpets

Follow up after replacement: things looks good so far !

931guru

So, I guess this "very experienced 944 mechanic" was blowing smoke???