Over the years we have seen a number of later 602/603 motors with real high oil consumption. Most got traded.

Last year we bought a 300SDL that had been condemned by another shop. It had so much oil going through the motor that it drained out of the tailpipe. We bought the car for scrap value and decided to examine the engine.

When we pulled the cylinder head we found that the number one cylinder had completely blown its head gasket into the timing chain galley. Every intake stroke sucked a gulp of oil and pumped it into the exhaust. The car had a dead miss.

This week we had a 91 300D 2.5T in the shop. It has a little diesel rattle but runs on all cylinders. The complaint is that it blows smoke so bad that those behind have to pull off the road. We thought we had a turbo problem but were real worried about the blow-by. We dropped the down pipe and it was sooty but dry. We ran the car with the cross pipe from the turbo to the intake; no difference. We hooked up an temp fuel supply and ran it with clean diesel. We TOOK a compression check. We should have guessed when the first time through the #1 cylinder was off 75psi from the others but the second time on #1 looked about the same.

Take a look at this picture and the following reply (I don't know how to do two pictures in one post):

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

If you look closely at the gasket picture and the following of the head, one can see that the oil hole that comes out of the block on the drivers side needs to feed the passage at the center of the head. As a result they gouged a groove from one side to the other.

If you look closely at the gasket it can be seen that the holes footprint on the gasket was real narrow on the ngine side. The gaskes metal plate is blown upward. It is my guess that as the gasket failed the oil from the passage got into the #1 cylinder one time so great that the hydro lock blasted the oil up through the gasket.

I presume that our second compression check that looked even with the rest was the result of filling the cylinder with oil during the checks of the other cylinders.

The reason I post is that this now is appearing to be a pattern failure. Maybe it is one that many know of. We wouldn't have been into this motor except the customer OKed an overhaul. Boy is he going to be tickled.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thank you, I will be looking for an SDL soon. Good info to have.

Does anyone one know what chassis / models these 602 / 603 motors came in?

I'm guessing W124 300E 2.5 and 86-87 W126 300SDL.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

And 87 300D/TD and 90-91 350SD/L and 92-93 300SD and 94-95 S350 and ?? 190D 2.5/t. I suppose there are non-US models to consider.

Sixto
95 S420
87 300SDL
83 300SD

So all of these engines have aluminum heads?

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

This now leaves me to wonder whether a bad head gasket could be the evil cause behind the 3.5L's rash of bent #1 rods and ovaled cylinders. If not a cause then could it be a contributing factor perhaps?

Of course we all know the connecting rods weren't properly beefed when they made the jump from 3L to 3.5L. Out of curiosity, how many miles on that 2.5L Steve?

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Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

And the MB passenger car Diesels since. The OM601 in the 190D 2.2 is of the same ilk.

Sixto
95 S420
87 300SDL
83 300SD

The 2.5 had 170k and the 300SDL had 280k.

I think there is a good chance of this bending rods. The oil in that groove is at operating pressure.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Wow, that's great info Steve. Thanks for posting the pictures and your narrative.

It would seem to make sense to me that a great deal of oil in any cylinder might cause a hydraulic lock condition that would easily bend a con rod.

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John Shellenberg
1998 C230 "Black Betty" 240K

http://img31.exs.cx/img31/4050/tophat6.gif

This is not real unusual in OM60x engines (I think early ones more commonly). I had it happen on one of my 601 engines and know of it happening on other 601 and 602 engines (I've diagnosed it correctly over the internet at least 3 times). I know of it happening on 2, 2.2 and 2.5 liter engines. I had never heard of it happening on a 603 (3 or 3.5 liter) engine. The picture look exactly like the blown gaskets I've seen.

The head gasket between the #1 cylinder and the chain vault blows out. I believe the "new" head gaskets revised in the late '80s reduce the probability a lot! NONE of the 601/602 engines had any con rod problems. This is NOT what happens with 603.97 engines as they burn oil because the rods are bent - not bend rods because they use oil! Their head gaskets ARE fine!

Marshall

Ah. Thanks Marshall. Still on the old MBCA list? Glad to see you've brought your vast MB knowledge here.

Interesting photos! That is probably why MB redesigned the cylinder head in that area - see attached photo, note the different oil gallery between the new (22-01, left) head and the old (14-01, right) head:

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Check out my website photos, documents, and movies!

Now ain't that sumthin! I sure would have started with the turbo, I've seen several blowing huge clouds of blue smoke due to ruined bearings, but I'd never have guessed a blown head gasket sucking oil out of the chaine case!

Guess I'd better have a closer look at the 220 D this week, wonder if I don't have a similar head gasket problem. Hmm. I'm pretty sure that's what has happened to the Volvo, too (also known for head gasket failures!)

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Very true stuff however, any rod can bend given a large enough dose of uncompressable liquid. Once the head is off and the t-chain is swinging, checking deck height is too simple a procedure to pass up. (I found a pair of bent rods in a 302 this way once, car had gotten a set of heads from another shop who could not get it to idle decently)I will always take the time to measure deck height on any engine with evidence of hydro-locking.

Gotta love the .97 mill, that thing would bend rods for the hell of it. Not to mention the number of 'em I've seen as of late with chain stretch causing lots O smoke and noise. I honestly think it was a static compression issue resulting from higher boost numbers and higher fuel loads.



Joe

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Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364