My 951 is experiencing a slow coolant loss, about 6 ounces every 1k miles or so. It never seems to drop down past the low mark. I have checked for signs of leaks and tightened all the clamps. The cap on the expansion tank looks good, there is no mixing of oil and coolant and there are no bubbles in the coolant. There was a small amount of moisture around the water pump for the turbo and some crust around the head gasket of the #1 cylinder. These are the only things I think might be causing the problem.

I have checked the compression of the engine and am getting 120 psi on all 4 cylinders when the engine is warm (idling for 10 minutes).

Any guesses as to what the issue(s) might be? I've searched the archives and I think my compression numbers are decent. The car has 80k.

Thanks!

 

120 across the board seems low to me, but we know the comp. gauges can be pretty far off from one another. Your coolant leak can be a very small one letting coolant come out as a fine mist, only under high pressure/temperature. This is always the hardest type to diagnose. Ofcorse then again they could be related... With all of that said, I would think the cap is most likely the culprit. If the level never drops down below min, I personally wouldn't worry about it much. Is the car overheating, has it ever?
Ahmet

 

Usually if your headgasket goes, only one cylinder will read low. Since yours is all even, the gasket sealing should be OK.

Also check your heater-valve hoses at the back of the engine. The plastic valve can develop cracks and leak coolant onto your clutch.

 

Ahmet/Danno

Thanks for the info. I took three readings on each cylinder and they were all the same. The car runs barely above the 1st mark on the dash temp gauge on hot days, otherwise it runs at or below it. The cap is probably original so I will try replacing it just for peace of mind. I don't see any coolant dripping on the ground, but will also check the heater valve hoses.

Thanks!

 

Does it start OK? Mine was idling very rough for ten seconds or so on startup. Turned out to be small amounts of coolant leaking into a cylinder.

 

"I have checked the compression of the engine and am getting 120 psi on all 4 cylinders when the engine is warm (idling for 10 minutes). "

I got 121 psi when the engine had been setting for 2 days cold...