89 944NA Oil Consumption

[ChrisN]

OK

I have lived with this problem for 2 years and have to make a decision as to which way to go and am looking for input.

My stock 89 944 burns approx 1 litre of oil for every two tanks of fuel. I originally considered the biggest problem to be leaks which have all been solved, I can now smell the oil burning but only under heavy acceraltion. Absolutely nothing on deceleration or during gear changes.

In addition to sealing all the oil leaks I have done all belts,water pump, tensioners etc. I have also pulled the head and put new guides and guide seals throughout as the guides were close to the limit wear wise. The frustrating thing was when I did the oil pan I also did rod bearings just to be sure !

While the head was pulled a quick inspection of the cylinders was done but I have to admitt that the main emphasis was placed on the head. I have done a compression test (cold) on this engine and it was excellent with all cylinders within 5 % of each other.

So the question is time for rings or is there something I have missed. Any thoughts are appreciated.

Thanks
Chris

[mlue]

If the rings and seals are good then may be this is your problem... take apart the Air box, AFM and J boot and check for oil. There should be oil residue but not alot of standing oil in this area.

If one or both O rings that seal the air/oil seperator is leaking this will cause oil to be sucked into the intake at high RPM through the hose from the air/oil seperator to the J boot. It is not clear why this happens, the air/oil seperator functions somewhat like a giant PCV valve but when the O rings start leaking it starts to function like a siphon and start sucking oil into the intake at high RPM.

Part Numbers are:
Seal 24x5 999-701-661-40
Seal 20x5 999-701-613-40

Your next steps should be:

remove intake manifold
remove oil filler tube from block
replace air/oil seperator O-rings

You may want to replace the large O ring in the oil filler cap as well (O-Ring 999-701-653-40) as that is another source of air leakage that affects the operation of the air/oil seperator.

[Techno Duck]

I agree with Mark.. i was burning about one quart every 1k miles. I changed the two o-rings on the air oil seperator (oil fill tube) aswell as the dip-stick o-ring and adressed a few other things while in the area. I am now only burning about 1qt every 3k miles. Still not spectacular but much better than before.

Just today however i pulled the j-boot (doing the headgasket) and noticed oil had pooled in the throttle body..though the throttle body was not nearly as bad looking as it used to be before i changed the o-rings. I have yet to change the o-ring on the oil fill cap, hopefully adressing that will fix the problem further.

What were the exact numbers on the compression test? Did you do a 'wet' test? Usually if you add a tea-spoon of oil into the spark plug hole and redo the test, if your compression numbers shoot up drastically this usually means you have worn piston rings. However i have read before the piston rings on these cars are fairly tough and do not fail all to often. Addressing the o-rings is a much cheaper job than changing the piston rings. Its a pain in the butt to remove the intake manifold and the fuel rail..but for the piston rings you are looking at removal of most of the front suspension, dropping the cross member and oil pan and a few other things....much more work.

[ChrisN]

Thanks for the input, I'll change the O rings and see what happens.

I know all about the pains associated with dropping the pan etc, I've already done that to solve the pan oil leaks, even did Rod bearings while I was in there !

I did see a very small change in compression readings when I added oil and again the readings were consistant across all cylinders. I have the exact numbers noted somewhere but if my memory serves me they were in the 225 - 235 range dry.


Chris