OM 606 Timing Chain Install: Chain is too long? HELP
 

Fellas,
I was hoping you could help me out with a few items:
#1 My mechanic fed the new timing chain through the engine by having it follow the old one. My understanding is that this is standard procedure to install a new timing chain. He is saying that the new timing chain is longer than the old timing chain. Can this be possible? Are there links that have to be removed from the new chain in order to make it fit? I purchased the chain from Fastlane last year in 2011 and I'm sure this is the correct part.

#2 I remember a DIY link with pictures and a description of timing chain replacement for the 606. Can someone direct me to this thread? I've been searching and can't find it.

Thank you,

I appreciate the links and follow up. However, I remember seeing a DIY tutorial with pictures that discusses chain removal and installation. Anybody know where that is?

Also, anyone know why my mechanic would think that after installing the new chain that it looks too long in comparison to the previous chain?

He should mark it. Rotate the engine if there is no interference and count links in comparison to the old one perhaps if he feels it is too long. It of course is possible someone messed up when the chain was fabricated.

Anything is possible in this world I suppose even if not likely. I assume the engine is rotatable in its current state. Even the wrong chain in the right box is not an impossibility.

Great idea. Thanks. The engine is rotateable in its current state. I'll mention this idea to my mechanic.

the pages I linked to, have references to needing to replace the tensioner... if yours is collapsed, it will appear long.

This begs the question of what kind of "mechanic" you have?

If he worked on any M/B in the past, he understands the principle of the chain tensioner and he probably removed the tensioner when doing the job to give some slack in the chain. Until the tensioner builds oil pressure again, the chain is going to appear to be "long".

It would be inconceivable that the chain is actually longer than spec as the chain is the component that keeps the camshaft timing to spec relative to the crankshaft.

Brian has a point. Rather than pre priming the newer ratchating type of tensioner. I suspect he would have had the opposite issue if he had not pulled it and reset it.

Or can it only be reset by oil pressure after reinsertion of the ram? There is still a chance the chain is too long. Overhead cam timing chains have been common for too long if he is a mechanic to miss much I would expect.

Their initial question about timing chain length was because I supplied them with a timing chain. My guess is if they had sourced the chain themselves they wouldn't have asked me about it. I'm pretty confident with my mechanic's abilities. Diesel Mercedes aren't their specialty but they work on tear downs of all types of engines. They are just being careful and just need some guidance to ensure everything is how it needs to be. I don't think they would have asked me for my input if they thought I was just a "dumb" Benz owner. They know I do a lot of DIY myself, and figured I could add some value to the table.

I appreciate the info on the tensioner. Installing a new tensioner and marking the chain and counting links should be what we need to do.

Thanks again, fellas. Definitely appreciated!