I bought this car about 2 mos. ago. Took it to my local shop and had them look it over. Replaced serpentine, glow plugs, changed oil and air filter and I was on my way. I noticed a noise between 2000 & 2500 RPM's that sounded like a slapping of something, and it accelerated/decelerated with RPM increase/decrease. So back to the shop I went... it was also burning oil... so I'm thinking this is indeed a lemon like everyone says the w140/603.971's are...

Had them check injectors. the "tip" was bad on #1 cylinder, so I had them all replaced. It ran better but still was not right, burning oil still. So they have now pulled the head, are having it fluxed and machined, new valve guides, etc. being installed. The #1 cylinder was the source of the burning oil. Seems the head gasket was blown out and allowing oil into the cylinder. So new gasket, machined head new valve guides and they think it'll be good to go with no oil issues, etc. Turbo checked out fine, not oil seal issues there....

Does this sound like something experience before by others? Would a bad injector cause the un-atomized fuel to compress and blow the head gasket out somewhere, i.e. to allow oil passage into the top end?

Thanks,
JMH

While waiting for the official word from Dave/gsxr...

There is a design problem with the early 603 heads or head gaskets with the effect of having oil leak into the #1 cylinder. I don't know if there's a fix short of replacing the head.

With the head off, have the shop check the cylinder bores for excessive wear. Have them check as well that the pistons crest per spec.

You might want to educate yourself on the experience of other 92-95 SD owners before opening your checkbook further. I mean make sure you're aware of what should be checked rather than spending on temporary relief.

Sixto
95 S420
87 300SDL

Dare I say it? Sixto stayed away from it well.

Rod bender.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Okay, I hear you both and thanks for posting up. Have either of you ever owned a car with this engine in it? I would not think that the piston bores are bad as the car started up perfectly fine with only 3 of 6 glowplugs working (state of condition when I bought it)............. if compression was out of tolerance, I would think it would have trouble starting or at least it would sputter and spit and vibrate. Despite the glow plug issue, this vehicle did neither.

Mechanic said the injector cause the gasket blowout, result of good compression and nowhere for the fuel to go... there is not any oil in the antifreeze nor antifreeze in the oil so I think there won't prove to be any cracks in the head.

I'm going this far with it, if that doesn't fix it or the odd sounds don't go away then this baby is headed for trade-in. As odd as this may sound, it actually runs great at highway speeds and the passenger compartment is so insulated that you actually cannot hear much if any engine noise without really tuning your ear.... it accelerates good, a/c blows cold... I think Mercedes blew it by switching away from the 617 engines though... my 1984 300D was bulletproof and was for the most part a joy to DIY on the routine maintenance stuff. Loved that car. Hope that proves to be the case with this rascal too...........if I can get these first bugs worked out of it.

Thanks for the replies... I appreciate.

JMH

I have a 1993 300SD with 233,000 miles on it.

I blew the head gasket at 102K miles and had the head
replaced. It was a different design! The old one had a
channel in front of the #1 cylinder and the gasket had
a channel worn through it letting oil into the cylinder.

I had to have the engine rebuilt because of a bent
connecting rod for the #1 cylinder. The pistons are
sold as sets.

At the same time, I had all the accessories checked and
rebuilt, etc. at the same time.

I haven't had any engine issues since. I also switched to
synthetic oil (Shell) at about 160,000 miles.

Considering the cost of redoing the head, you may want to
consider replacing it with a new head assembly. It will
cost you a little more but you should get the latest
design specification. When I did it, the difference was
about $300-$400.

Also, I recall that all the headbolts have to be replaced.
The old ones cannot be reused.

-Ralph

__________________
Ralph Burnette
1993 300SD (286k + miles)
2000 SL500
2001 ML320

You must, absolutely must do this. Just because you don't see oval bores doesn't mean a rod isn't bent. If you don't have this done, then you could be throwing away all this money you're spending on the current repairs.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

I would dispute this hypothesis. You can crank your engine all winter long with no glow plug relay and the head gasket shouldn't blow. The volume of liquid fuel in the combustion chamber is insignificant to the static compression ratio.

Sixto
95 S420
87 300SDL

A footnote to my comments and the other comment concerning connecting rods and pistons.

When we pulled the head we could see how the piston
came up crooked because of the oil marks near the top
of the cylinder.

When we pulled the piston the connecting rod looked
straight. HOWEVER, when it was gauged, it was found to
be bent. Add the bent connecting rod to tolerences in
bearings, etc. and you can find a piston quite a bit out of
alignment.

BTW, my car would start and run with the bent connecting
rod. I never new it was bent. However, oil usage keep
increasing and then all hell broke loose one day when I
was getting a few miles to a quart of oil.

In the process of rebuilding my engine, my mechanic
sleeved the bores.

Before tossing the car, I would look hard at the cost of
rebuilding it, total miles on the car, etc. As I said earlier,
I now have over 233,000 on mine and the engine is fine.

As a maintenance note, I did have to have the valve seals
replaced at 186,000 miles due to some leakage. The
engine generates a significant amount of heat which tends
to harden valve seals, etc.

-Ralph

__________________
Ralph Burnette
1993 300SD (286k + miles)
2000 SL500
2001 ML320