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Has anyone had trouble with their 944 burning oil?  My 1987 944S is burning a quart every 35 minutes on the track. Compression and leak down tests look as good as from the factory new. I replaced the air oil separator rings. I was told to add a crank case breather, but others say if the rings are good, the breather is not the problem and will not help. Others say it is the brand of oil. I was using Liqui Moly Racing Synthetic 10w-60. Any ideas?

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I would ask this question over on the Pelican Parts or Rennlist forums.  If you cannot find an answer at either of those forums, you might want to try the Spec 944 section of the NASA forums.  The PCA may also have appropriate forums, if you happen to be a member.

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Burning oil means its getting into the combustion chamber somehow.  Only 3 ways I can think of.

 

1. Rings

2. Valve Stem Seals

3. Intake System (PCV?)

 

It could still be #1 even with good leakdown and compression #'s, if your oil control rings are gummed up.  Whats the history of the motor?  Have you considered running some diesel or seafoam in the crankcase to loosen any gunk (could be risky)?

 

#2 is hard to test for, but probably a pretty good bet if the motor has high miles

 

#3 you should be able to eliminate pretty easily.  Vent the PCV to atmosphere or add a catch can, see if it gets better.

 

FYI I don't know 944's specifically, but this should pretty well apply to any car

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9 hours ago, Scrappy Grappler said:

Has anyone had trouble with their 944 burning oil?  My 1987 944S is burning a quart every 35 minutes on the track. Compression and leak down tests look as good as from the factory new. I replaced the air oil separator rings. I was told to add a crank case breather, but others say if the rings are good, the breather is not the problem and will not help. Others say it is the brand of oil. I was using Liqui Moly Racing Synthetic 10w-60. Any ideas?

Do you have a good crankcase evac system? if you don't get one.  You aren't putting around on the streets you are running between 3500-6000 (give or  take) for hours at a time. That builds up a lot of pressure in your engine. The oil has to go somewhere. 

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Pulling a vacuum in the crankcase will counteract oil being sucked past weak guides/seals when off throttle at high rpm.

 

A catch can in the middle won't reduce oil migration but will keep it from being burned and reducing your octane level and you can see where the oil is going.

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3 hours ago, Huggy said:

Burning oil means its getting into the combustion chamber somehow.  Only 3 ways I can think of.

 

1. Rings

2. Valve Stem Seals

3. Intake System (PCV?)

#2 is a good bet... after a machinist rebuilt our head with new valve stem seals, our oil consumption rate dropped by over half.

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Are you certain it is burning and not leaking? I have heard of nightmares with the front cover on those motors. Because it is leaking greatest at high engine speed keep in mind it may not show up like a drip as that means you are likely moving fast when it leaks. It's German so of course it leaves spots when you pit, but how significant. You might want to run a test and run a mineral oil for a bit and see if oil loss goes away or slows down.

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