Uses oil

Mac · 04-22-2000, 06:50 PM

The motor has 7K on new rebuild, but the car (944T) has 100k. The car doesn't leak oil, but I use about one qt. of oil in 500 miles. The oil and antifreeze is clean.I looked into the intercooler and found a very very light trace of oil.The car doesn't seem to be burning it,no smoke I have been told. Can the turbo be problem ?

Pilot_951S · 04-22-2000, 09:57 PM

If I remember correctly (and I may not) the 951 turbo is oil and water cooled. If there is oil in the intercooler the only place I can think that the oil is coming from is the turbocharger.

What side of the intercooler is the oil on, is on the turbo side or the intake side?

I'm just taking a stab in the dark here.
Anybody else?

Of course if the turbo isn't the culprit it could also be a bad piston ring (I have that problem currently) my car burns oil about every 400-800 miles depending on how much boost I use. (bad ring lets pressure through, when the car is under high boost the cranbkcase gest pressurized and then oil spews up past the ring as the pressure diminishes.)

Is your oil consumption boost dependent?

Mac · 04-23-2000, 08:20 AM

Thanks for your ideas. I did check both sides of the intercooler, along with inlet/outlet tubes, to find about the same amount of oil present . The oil consumption doesn't seem to vary on the amount of boost it sees in the 500 miles. My other concern is the cat. , could it be clogging with this amount of oil consumption. NOTE: The car runs very,very strong ,with 1.9 bar boost (.9 bar actual)I'm using Mobile 1 oil 15-50W .The turbo is both oil and water cooled.

Pilot_951S · 04-23-2000, 11:04 AM

Well I'm out of ideas.

1.2gees · 1.2gees's Garage

I have a 944 that I had a valve job on, though mine is not turbocharged, your problem isn't the turbo itself, so this might be helpful:
Before my valve job, I used to burn quite large amounts of oil, with not really visible smoke coming out the tailpipe. Afterwards however, I can't tell the difference in oil level after sustained high speed driving for a good 1500miles, holding the car at more than 4000rpm for more than 95% of the time, with frequent downshifts to 4th. I do recall that for about the first 1000miles or so consumption was higher.

I know of a 944 that had a valve job as well, but he drove his car hard from mile 1, and burned oil pretty bad, his car didn't seem to loose any power either, but the valves didn't seat right, so they let oil past them, not a good thing.

It sounds to me like you run the car hard, I hope that's not how you started driving it without breaking it in...Valve seals more specifically would cause this, and according to my mechanic, this would increase the oil consumption with no change in power/noise. I hope this helps.
Ahmet

1.2gees · 1.2gees's Garage

Oh by the way, the car's fuel/air mixture has been checked/adjusted at not too infrequent intervals, according to the records but my cat is falling apart! (Getting a test pipe soon)

Pilot_951S · 04-24-2000, 01:38 AM

1.2gees,

Seeing that my problem is boost dependent could I be having the same problem you just described. I tried to be easy on the boost after having my head done, (I needed a new gasket so I had the head ported and polished) but maybe I wasn't easy on it long enough? Maybe I have a valve seat problem only at the #2 cylinder? I had a leak down test performed (1,3,4 all at 2% but 2 at 8%).

jody · 04-24-2000, 04:53 AM

Do a spark plug test ( look for oil ). Try regular oil. Do a compression check. Thats what I would do anyway. Good luck.

1.2gees · 1.2gees's Garage

I agree with jody here, that's a little too much for #2, if indeed you need a piston ring, you're in for a huge bill+ not all places can rebuild a 944 bottom end, so be careful, but first, do a compression check, if you have the Haynes manual, it gives a pretty good idea about how to determine if it's valves or rings that you need. I've seen many 944s that needed 4 or even 5 valve jobs, but the bottom end hasn't been apart, up to say 250-300k. Again I don't have much first hand experiance with the 951, (hope to change that with my next car) but both cars have a very similar bottom end other than the different compression ratio, so I would say the turbo has a durable bottom end too, but that's just what's common, you might as well need a piston ring, lets hope not... Anyway, so if you've got a Haynes manual, you can find out if it's piston rings or valves that's leaking, but you need a compression gauge, also don't forget to tell the place that did the port&polish on your car that it's burning oil that bad, see what they say.

Pilot_951S · 04-24-2000, 08:54 AM

Well there is oil on the #2 plug, at tleast there wwas last time I checked it. I replaced it with a new one. The place that did the head can do the whole motor, can actually do anything I want to the motor. (they build 951 Race Cars for fun, and for customers, best 944 technicians I have ever encounterd, PCA memebrs too) Anyway the first scenario (the bad ring, or a a score in teh cylinder wall) was suggested by them after they gav it a thorough going over. (as I recall they also di a compression test so that would acccount for their assesment about top end vs bottom end, pressurize the cylinder and see where it is going right?)

Also I should note that the car runs alot of boost using the Weltmeister dual chip set. And the guy who owned it before me beat the snot out of it. I fixed all kinds of ridiculous problem when I bought it, bhut I knew I was goignt o have to tear it down sooner or later. I'll probably build a 2.8 out of it, or a high boost 2.5.

1.2gees · 1.2gees's Garage

Sounds like the shop you're going to know what they're doing, I'm glad you were ready to tear the engine down, as suggested by the mechanic. Also, I hear that the 2.8 is a much better set up for high boost=high horsepower, I'm sure they'd tell you that too, however I would take my time before the tear down, I doubt you'd hurt anything besides the cat. (that's if you're going to use a different block, if not I suppose you could damage the engine you've got now if indeed it does have damage at the cylinder wall)By the way, oil in the #2 cylinder does not necessarily mean it's the rings, ask the shop, they should be able to tell you valves/ or rings. Do a compression check, and recheck with a couple of drops of oil (drop em in through the spark plug hole), if the reading goes significantly higher, than it's rings.
Ahmet.

Pilot_951S · 04-24-2000, 11:34 AM

Thanks for the advice!

To my knowledge the 2.8 setup is better because the longer stroke afffords a more powerful exhaust pulse, and hence drives the Turbo better.

I can't hurt the cat. The previous owner hollowed it out (he was a fool, I fell like I rescueed the car from him) so it isn't going to get clogged, cause there is nothing to clog. When (not if) I tear down the motor I'm going to put in a new cat cause hey I like clean air, but the car still passes emmissions so it is running well.

I'll just call and ask them they keep great records, when I spoke to them I seem to remeber them saying it was either a bad ring or a cylinder score cause the leak was on the bottom end. Anyway the car needs to go in soon for the 1st,2nd, adn 3rd gear syncros, and some suspensionmods I've been planning so I'lll have a chat with them then.

(They have access to Bilstein Race dampers custom valved for 951 applications, complete with adjustable spring perches. I can't wait to get them on the car.)

1.2gees · 1.2gees's Garage

Sounds like you already know what you're doing, ask them if running the car as it is would damage anything else, and good luck with your car, as I've said earlier, keep us updated, you might want to give the excite 944 club a try too, I think I've posted a link to it under "Angry Transaxle"

Pilot_951S · 04-24-2000, 01:47 PM

They figured if I didn't track the car (limit my craziness to autoX) I should be able to get about two years out of it before I need to mess with it, they also said the average street driver wouldn't notice cause they woudln't get into the boost nearly as much as I do, they were very adamant about the fact that I am NOT an average driver (probably something to do with me complaining about vibrations at 150mph, we fixed them btw). They figured an average driver would not need to bother with the bottom end until maybe 200k miles (car has 98K on it now)

Also I joined the excite club a few days ago, haven't had time to check it out much.

Lawrence Coppari · 04-24-2000, 03:16 PM

Had a 1986 300E MB. At 70K it suddenly began using oil at a rate of 500 miles/quart. No blue smoke from exhaust at any time. Took it to dealer. They said it was worn valve guides due to bad metalurgy. Replaced guides. Problem fixed. No charge by the way - one of those unpublicized recalls...

1.2gees · 1.2gees's Garage

Pilot, I'm glad you joined excite, there is lots of useful info, as well as lots of useless info, but I think you'll like it,

A friend of mine had a nissan 300zx, at 166k it started using about 1 quart every 200 miles or so, no blue smoke coming out the tail pipe(previous to that), and no leaks, two days later the car wouldn't start. We took the engine apart, and didn't do a proper teardown, but did find a broken crank/rod as well as totally screwed up bearings, I don't think this helps you any, but it's interesting so I posted it...