350SD, oil consumption worsens - PeachParts Mercedes-Benz Forum

DslBnz · #1 12-29-2004, 07:56 PM

I own a '91 350SD with 286K miles on the clock. For those that don't know, I have been monitoring oil consumption tendencies from over 1 year ago in August. From there, consumption was 1500 miles per qt. on average. Consumption has steadily increased, and the last fill noted the 250 mile per qt marker. I have no idea what's going on. Could valve seals be out of the question for cylinder #1?

Here is a comparison.

One soundclip is in normal speed. Comparing a 3.0 liter OM603(not mine) that needs a new set of injectors to my 3.5 liter(2nd half of sound bite).

http://www.ejzcars.com/350soundnorm.wav

The next soundclip is 50% the speed of normalcy. I suppose it would help to isolate the sounds of the engine.

http://www.ejzcars.com/350sound.wav

The car is starting to blow oil smoke embarrassingly heavy right now. Just happened as of today. Any speeds below 2K rpm cause it to smoke excessively. At an extended idle, upon taking off, the vehicle behind me is engulfed in the blueish, foul smelling haze. At the very least, on the optimistic side, I don't have any tailgaters anymore. However, there are no noises from the engine. Except excessive injector knock from cylinder #1. It looks like <100 miles per qt. if this keeps up.

Should I be concerned?

DslBnz · #2 12-29-2004, 08:04 PM

Oh, I forgot to add. The engine longblock was replaced in 1995. Engine has about 198K miles, I believe.

sokoloff · #3 12-29-2004, 09:20 PM

See my reply on the Tech Forum.

Len

Hatterasguy · #4 12-29-2004, 10:22 PM

Would a compression or leak down test tell you anything? I would imagin if a rod was bending that badly either blowby would be going up or the rod is probably about to go through the block.

I would start to hunt for a used engine or a new short block.

DslBnz · #5 12-29-2004, 10:32 PM

Quote:

Originally Posted by Hatterasguy

Would a compression or leak down test tell you anything? I would imagin if a rod was bending that badly either blowby would be going up or the rod is probably about to go through the block.

I would start to hunt for a used engine or a new short block.

Yeah. I did a semi-compression test the other day. It was 13 degrees outside, and it wouldn't start! Glowed it three times in fact! The starter locked once or twice due to the wetness inside the system, I assume.

Last year at -10 degrees, it started without much ado.

See, why I am a little concerned?

I suppose I still have my other cars if this one goes down. Hattie, this car has gotten downright obnoxious. Something has to be done. I have a feeling she'll be burning more oil than what's from the tank pretty soon.

Hatterasguy · #6 12-29-2004, 10:35 PM

Well take your time and find a good used engine. Or stop running that one, maybe you could re sleeve the block if it isn't to far gone. I would stop driving it and figure out what to do.

DslBnz · #7 12-29-2004, 10:50 PM

Thanks.

I will be driving this one ONLY for in-town usage. When it fails, at least I won't be stranded out in the boondocks. I guess my SDL will inherit the heavier driving.

To be honest, Hattie, I don't really need this car. I have enough cars as it is. As much as it hurts, it might be time to put it to rest, afterall. Its probably easier and cheaper to get a used 3.0 liter engine than pulling my 3.5 apart for a random diagnosis.

Funny, after all the trips with this car, it has never failed me once. Even when running its roughest. From its quiet and serene cabin, to it's smokiest battle with death, its never failed me, yet. Da**!

You know, of course, this engine is manufactured the 95 model year? The year with the modifications done to the rods?

Rick Miley · #8 12-30-2004, 10:00 AM

Well, knowing the history of the 350, one would naturally assume that #1 bore is now oval and leaking a whole bunch of oil. However, that amount of oil use could also come from bad turbo oil seals. This should be easy enough to check - take the intake apart and see if it is loaded up with oil.