I am one of the unfortunate souls who purchased the 3.5 engine diesel.
At 70K, the car is using one qt every 300 to 400 miles. I am now
dealing directly with MB. The local dealer performed a compression and
leaks test with the following results: the cylinder # will be followed
by the compression/leak down: (1)400/5% (2)440/10% (3) 460/10%
(4)480/70% (5)480/40% (6)450/10%

Anyone have any ideas about what these values reveal?

David M. Stagner

was wondering year, model, and make

------------------
'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

It is a 1993 300SD

1993 300SD

Davidtoo,

Try searching this forum for 350SDL, oil consumption, and whatever else you can think of that relates, like engine family, whatever it is.

There were some good posts on this engine a few months ago. Until that time, I didn't know that there were problems with it. This doesn't mean that everyone has had problems with this engine.

From your cylinder test, I'm led to wonder about valve stem seal problems. However, I've never done leakdown tests, so I'm not sure how to relate these. I do know that for the oil consumption problem in a diesel to be related to the lower end, the compression typically is very low. Your compression readings are good. I've always only been able to do a compression test. If I ignore the leakdown numbers as if I never saw them, my reaction is that the oil consumption problem is in the top.

How does the engine run?

Good luck,

------------------
Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

If you have a 300 SDL, no need to worry, at least about somethings. Are you sure you don't have a 350 SDL?

Could somone please clarify the models discussed here. My records (Canadian sales) show that Mercedes sold the W126-bodied 350SDL in 1990 and 1991. The engine was the 603.970 and was rated at 134 HP.
In 1992 and 1993 they offered the W140 300SD. In 1994 and 1995 they called the same model S350 TurboDiesel. All W140 cars had the 3.5 L6 SOHC turbo-diesel engine that was rated at 148 HP. Were US sales different and what engine did the W140 have?

The engine(s) are described in a paper by John Blazer:

THE ENGINE

The problem engine is a 3,449 cubic centimeter displacement in-line
6-cylinder turbo-charged diesel engine. Diesel engines were first used
in the W-116 300SDL S-Class beginning in 1978, continuing through 1980.
That engine was a 3 liter 5 cylinder turbodiesel, model 617. The W-126
S-Class debuted in 1981 with that same engine, which was changed to a
3.0 litre 6 cylinder (the 603.96x) in 1986-87. This same 3.0 liter
engine was also used in the W-124 300D and 300TD in model year 1987.
These engines are NOT the problem. That engine block and head, however,
were the starting point for the 3.5 liter version. For comparison
purposes it will be helpful to know how many of these 6 cylinder 3.0
liter versions were in use:

Year Body Model Engine Model # Sold

1987 W-124 300D/300TD 603.960
6,022
1986-87 W-126 300SDL 603.961 13,830

Source: Robert Nitske's book "Mercedes-Benz Production Models Book,"
Motorbooks International.

MODELS INVOLVED

The problem engine was first installed in 1990 and, with minor
modifications, was used through 1995. The models, with number of cars
sold in the U.S. and the list price, are as follows:

Year Body Model Engine Model # Sold $ MSRP

1990 W-126 350SDL 603.970 855 56,800
1991 W-126 350SD/SDL 603.970 3,914 53,900/57,800
1992 W-140 300SD 603.971 1,131 69,400
1993 W-140 300SD 603.971 1,005 69,900
1994 W-140 S350 603.971 672 70,600
1995 W-140 S350 603.971 425
65,900

Source: MBUSA Web Site, 12-Year Model Overview