1994 350 s diesal oil burn? - PeachParts Mercedes-Benz Forum

jjohn81602 · #1 07-08-2006, 01:41 PM

i have a 1994 350 s turbo diesal. that runs perfect.but have a small problem the car consumes oil very fast. it does not leak out. it must burn thru exsaust.any ideas. would be greatly appreciated!

stephenson · #2 07-08-2006, 02:32 PM

How many miles on it?

This engine is known for serious oil burning, following an internal event that slightly bends a rod ... once this happens, it's engine rebuild or replacement time.

Might be something else, but my understanding when it happens you go from normal ops to massive oil burning very, very quickly.

raMBow · #3 07-08-2006, 03:20 PM

Might be time to check compression

My brother has a '91 350SDL with over 250k on it and supposedly no problems yet.

#4 07-08-2006, 03:22 PM

Sounds like it's rebuild/replacement time.

Hatterasguy · #5 07-08-2006, 08:15 PM

I'd sudjest a quick trade in, unless you are in love with the car.

That engine is a real dud, worst diesel MB has made to date.

You may get lucky and it may be the turbo seals.

How much oil are you burning??

Rick Miley · #6 07-08-2006, 09:23 PM

Quote:

Originally Posted by Hatterasguy

You may get lucky and it may be the turbo seals.

YES! For goodness sake, check the easy stuff first.

stephenson · #7 07-10-2006, 11:51 AM

Agreed - did not mean to imply should just run ... however, it sounded as if the oil burning started quickly and was extreme ... if extreme if could be the turbo seal, but the 603 engine ... aack ... some are lucky (as I have been with mine), but most aren't.

If a slow increase in oil burning it could be valve seals, etc ... but, again, the initial post did not sound like this ...

guage · #8 07-10-2006, 11:56 AM

Quote:

Originally Posted by jjohn81602

i have a 1994 350 s turbo diesal. that runs perfect.but have a small problem the car consumes oil very fast. it does not leak out. it must burn thru exsaust.any ideas. would be greatly appreciated!

I thought these were only produced in 90 & 91?
350SDL & 350SD.
Or is this something different?

dieseldiehard · #9 07-10-2006, 12:06 PM

hold on a sec!
the 603 came in several varieties, the 603.960 is the 2.995 liter engine use in the used in the '87 300D, '86 and '87 300TD and the SDL turbos.
It's not a "bad" engine, if you get the trap oxidizer off of it and the owners replace the radiator when its plugged and use the right coolant and R&R the vacuum pump, all those models are prone to problems related to those things.

The '90 and '91 350SDL and '91 350SD both use the 603.970 engine. That is however a sad story and a blemish to MB's engineering skills. What with the rod problems its another thing altogether so please don't classify everything as a 603 problem
the '94 (W140 chassis) used the 603.971
I don't have any direct knowledge of what changes were made to the engine but presume they modified it, but its still suspect

andmoon · #10 07-10-2006, 12:27 PM

Why did MB make this engine for 4 years?
You'd think by 2 years the rod bending was known.

stephenson · #11 07-10-2006, 04:38 PM

Aacckkk ... sorry, I shortened it ... the 3.5 in 90/91 was 603.907 and then 603.971 in the W140, right? It was this engine that was bad juju ...

Mine appears to be OK as I pass the 185K mile mark - that said, who knows ...

Many of these "bad engines" start the massive oil burn much earlier in their cycles - 60-80K miles or so from my reading ... but, the lead in appears to be quite similar - everything is generally OK and then the "event" happens, then massive oil burning - a quart every couple hundred miles, or worse.

I was a bit proactive in mine after trying to come up with anything that might make a difference ... I pulled the entire intake system (it was 75% blocked in the area near the EGR valve cover vent into the intake system) ... took days to clean out - multiple dips at machine shop followed by hours of pulling rags and brushes through it. My experience with the car had been that it would, on occasion, under hard acceleration, pause with a puff of brown smoke - my thought was that the engine was ingesting chunks of the coked oil (from the valve cover fumes) into the 1 and/or 2 cylinder since that was closest to the blockages (and, are reportedly, also the rods that bend most often).

Just some thoughts!

t walgamuth · #12 07-10-2006, 08:10 PM

just to confuse us they called the 140 diesel a 300sd but it had the 3.5 motor too.

i have a 90 350sdl. i bought it right with a blown head gasket and did that and an extensive valve job. it uses some oil but not excessive. my compression cold is 300 on 1-4 290 on 5 and 280 on 6. it is smooth powerful and quiet. a real dream to drive and not much slower than my 500sec. and will do up to 26 mpg hiway.

tom w

Hatterasguy · #13 07-11-2006, 07:10 PM

The 300SD can be a 1992-93 W140 with the 3.5L 603 fitted.

This car continued in production until 1995. Although it was called the S350D from 1994-95.

At some point in the late 90's MB fitted the turbo charged, intercooled, 606 into the W140 body. This created probably one of the all time great diesel cars they offered, to bad they didn't sell them here.

How quickly did this problem come about?