Sudden oil consumption - PeachParts Mercedes-Benz Forum

#1 10-25-2002, 02:43 AM

Over the last 10,000 miles I have been slowly but steadily increasing oil consumption.

At 272,000 miles I replaced my timing chain, it had ~13 degrees of stretch. I screwed up a bit and the chain was one tooth off.

At 276,000 I corrected the chain, and had the injection pump retimed.

Here is where I noticed the oil consumption. Until this point I used ZERO oil in 4,000 miles, I do mean zero. It started at adding a 1/2 qt in 3,000 miles now most recently the oil light is coming on as soon as 1000-1500 miles after an oil change, which is atleast 1qt. I am very concerned.

I have no more than usual visible smoke (very little). 99% of my driving is highway at 80 to 90mph - I have noticed it is using more oil the faster I drive.

Maybe it's my turbo? I really have no issues with the engine, it starts on a 1/2 crank and it's been 35F here one night. Still has good power, sounds great, I don't get it. There is no more oil on the street than usual, so I don't think I'm leaking it.

Help!

psfred · #2 10-25-2002, 08:37 PM

Turbo is a possibility -- look for excessive oil in the intake with a dry blowby tube (that means check blowby, too).

The other things to check are leaking front cover (these are a real pain to seal) and a dead valve cover gasket. Those will leak more at speed than around town, and you can dump quite a bit of oil off them -- and it will not show up on the drive, it stays in the tray until you get up to speed and it blows off.

My 300D uses about a quart in 8000 miles -- last oil change was put off a bit....

Peter

#3 10-25-2002, 09:35 PM

I actually removed the belly pans on my car quite some time ago for ease of access. When I was under the car looking at my pass side motor mount, there was some fresh oil at the turbo hosing connections, can I tell if the turbo is worn by wriggling the shaft? It still seems to work fine, makes no loud noise, etc.

psfred · #4 10-25-2002, 10:43 PM

Yes, you can check. Turbo shaft must turn freely with no rough or sticky spots in rotation, and must not have any axial play. Some will have radial play due to the nature of the bearing (it's a floating design).

If it is bad enough to leak oil, it will have rough spots, will have excess play, and will be coated with oil.

And, a dead turbo is VERY quiet, since it won't spin until you really stand on the accelerator.....!

Peter

kerry · #5 10-26-2002, 12:51 PM

I have read on this forum that a bad vacuum pump diaphragm can cause oil consumption.

#6 10-26-2002, 03:48 PM

Vacuum pump replaced @ 239K. I don't think it would be bad already..

Aaron · #7 10-26-2002, 05:14 PM

Two BIG spots to watch on the turbodiesels (particularly the 617) are the turbo drain seal and the oil filter housing-to-block gasket. My '83 is leaking like a sieve from both spots now so I've got the necessary gaskets and seals on the way. Will tear into it sometime next week. I just changed my oil maybe 500 mls ago and I've already had to put 1qt in!! And it doesn't use oil. I can easily see the puddles forming under the car from maybe as little as 1/2 hour of sitting. Baaad!!

md21722 · #8 10-26-2002, 09:41 PM

I'm VERY interested in the concept of the turbo leaking oil into the intake. I have oil buildup (500 miles after Engine Brite) on the intake pipe right above the turbo. The intake crossover tube & manifold are black oily. there is oil in the line from the intake to overboost switchover. The EGR vacuum line is not working. There is no oil leaking from the bottom of the turbo. I remove my oil filler cap and feel almost nothing, very small puffs of air is the most - so I don't think is blowly. '87 300D 261Kmi - with a internally leaky turbo, what's the easiest way to check the shaft? (I've NEVER messed with the exhaust side of any engine).

Thanks,
Brian

psfred · #9 10-26-2002, 10:26 PM

Brian:

The intake hose from the air filter to turbo is held on by a hose clamp on each end. Remove clamps and slide off hose. Front of turbo compressor wheel is about 2" inside, easy to reach.

Should be easy to tell if it is working properly -- you get a big "kick in the pants" at about 2000 rpm, car takes off! No blast = no turbo!

Peter

md21722 · #10 10-26-2002, 10:40 PM

Hi,

So I can "feel" for bearing play in the shaft without seeing it? That's a LOT easier than removing the turbo! I'll try that first.

I do get a pretty good power out of the car. But I get a lot of oil in the intake, and about 6 times now, I've gotten a LOT of black smoke (4 times WITHOUT a blast, 2 times with). The smoke/power could be ALDA or turbo wastegate problem ?

Brian

psfred · #11 10-27-2002, 11:53 AM

Well, lets see. If you do a lot of stop and go city driving and drive with a light foot, you can get a lot of soot in the EGR and catalyst, so when you stand on it for the first time in a while, all the loose soot blows out. Quite a cloud, but it will only happen once. After than, little or no smoke.

Your EGR valve could be sticking open at low speed after running a while -- this will cause a funny muffled rattle in the engine and HUGE clouds of inky black smoke from incomplete combustion. My old Volvo did this all the time before I repaired the EGR -- great for getting idiots to back off -- floor it, downshift the auto, and the car behind would usually dissapear in the smoke cloud! Must have been nasty back there! I no longer get more smoke that a little black flickering up above the trunk. The easiest test here is to disconnect the EGR line at the valve and plug it, and see if the smoke quits. If so, you must either replace the valve or permanently disable it.

If I really stand on it from a stop, the 300D will poop out a small black cloud, about half the size of the car, once in a while, worse cold. Never more than that.

Good luck -- I'd get on the EGR.

Peter

md21722 · #12 10-27-2002, 01:18 PM

The EGR has been disabled for about 100Kmi.

When this first happened, I was in Cheyenne, Wyoming on vacation, heading home to Tennessee. Twice on my trip, the car idled for about 1-1/4 hrs. Could be a lot of soot built up inside, I guess and it took a while for it to clean up. Hasn't happened in a while.

But cruise is surging two weeks ago, and I think the ALDA is leaking/faulty. I'll probably replace it sinec I have another one.

Will stlll check the turbo.

Thanks.