I've been informed by my mechanic that my engine tapping may be due to a wrist pin in one of the cylinders in the lower end. Can any other 603 owners comment on this problem and their experiences with it? I'm particularly interested in determining what to listen for. TIA.

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Chris

'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
'99 C280 Sport sold
'85 190E 2.3 sold

The keyword in your statement is "maybe" The only way to be sure is to drop the pan and check. You may have an out of round cylinder usually caused by a bent rod and what you hear is the piston skirt slapping against the cylinder wall. does you car burn a lot of oil?

If your car isn't burning any oil and is running fine I wouldn't worry about it. Your going to need a short block if it is a wrist pin so just drive it. I don't believe that a 603 in as good as condition as yours would have a bad wrist pin.

Lets see my 603:
Hum's in the morning, alternater or power steering pump going south?

But wait first it skip's I need to get my rebuilt injectors tested.

Then the lifters tick away, althoug Delvac 1 is helping.

Then their is another sound I can't quite trace. I think it is coming from injecter 4 or 5. Sounds like an injector is not working right. Maybe related to skipping problem?

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Wrist pin will be a metalic knock about half way up the cylinder, unlike a rod knock, usually definitely at the crank level.

Never heard of a 603 with a bad wrist pin, though. Repair would be a new sleeve in the piston rod unless the piston itself was worn, and I don't believe this will happen on a turbo 603 -- oil spray cooled pistons! No way to get a lubrication failure when everything is bathed in oil, to say nothing of the fact that the wrist pin is pressure lubed from the crank....

More likely you have a bad injector or bent rod. Bent rod will be obvious, they clank like crazy as the piston flogs the cylinder to death, burns HUGE quantities of oil.

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!

Guys - the 3.0L engines DO NOT bend rods. Only the 3.5L engines do that. I have not heard of a single 3.0L with a bent rod.

That said, my white 87 had a light tapping that I thought was a wrist pin noise myself. It was not valvetrain and not injection noise. It was quiet enough that I could only hear it at low speeds with the window down, under light load. The noise was not present at idle. The car was wrecked so I never got to see if it would get worse. I have heard of a bad wrist pin on a 603 before. I think AJ had that on his original engine. Peter is correct about the repair (IF it gets bad enough to bother with!), pull thatpiston & rod, sleeve the pin or otherwise fix it, re-install.

It's still an odd failure though... I'd want to get a second or third opinion from a few different OM603 experts before messing with this at all.

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Dave
Boise, ID
Check out my website photos, documents, and movies!

Are 603 wrist pins pressed or floating?

Sixto
95 S420
87 300SDL

Thank you all for the input. I've put 1,300 mi on the new head in the last two weeks and can report zero oil loss, so I'm confident it's not a rod issue. I'm going to drive it long and hard the next couple of weekends before taking it back to my indy for a follow-up diagnosis. If he still believes it may be a wrist pin I'll take it down to AJ and Gary, certified local 603 experts, at MB of Sac for a second and third opinion.

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Chris

'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
'99 C280 Sport sold
'85 190E 2.3 sold