This repair manual is your best friend. It's the only one I've found that covers the M102.980 engine. Available at the usual sources including Amazon.

I don't know about the single-to-double conversion kit but would be interested in knowing more if you find out anything.

 

I've done this job a couple of times if you need some more detail. But I used the manual Eiderdown shows above with success. Back when this job was fairly common, a Mercedes Benz agent told me he insisted his mechanics (somewhere in SE Asia) fabricated two plates that were to be bolted on the cylinder head and which trapped the two ends of the chain on the cam chain wheel as the crank was rotated to make it a one person job.
I didn't do this and I don't know where the plates would be bolted but its worth thinking about. You need to have an assistant that knows what you are trying to achieve. I used my wife, she got it right first time, dropped the chain the second time.

As far as a double row conversion goes, I too would like to know more. The later 102's used in the W124 had double row so maybe those parts are interchangeable.

Is your chain stretched? I was searching on this forum and saw an owner of a 102 motor had 400k km on his chain and I wondered if I was changing the chains out too soon.

 

Thanks for the info! Mine has 250k km on it and I’ve heard it was a weak spot on the m102 engines.

 

Yes I have heard the same but never read of any actual occurrences. The Haynes 190E (W124) manual has a good write up on changing a single row chain on a 102 motor, and that part of the engine is identical to yours. At 250km it might be time.

The only extra I would add to the published procedure is that prior to starting, be thoroughly conversant with the valve and ignition timing of your engine (if you are not already). Because if you stuff it up and drop one end of the chain into the guts of the motor, its a lot less stress to get back to where it needs to be if you are prepared. Valve timing is easy: set the crankshaft at TDC and check the line on the camshaft lines up. Ignition timing at TDC; take the distributor cap off and observe the rotor pointing to the line on the distributor plate, use a rule to accurately measure the gap either side of the adjustment lock down bolt. Take photo's if necessary.

These are an interference motor, without a chain you will have problems winding over the crank independent of the cam and vice versa.

Also, before you grind off a rivet, wind the chain through its length just to make sure it does not have a quick link fitted; originals won't have but a few after market chains do.

When I first did this job I got advice from an MB agency supervisor (it was a small town in a small country) and he said they always fit a new timing chain tensioner when fitting a new chain because it avoided potential problems with warranty claims. I now have a bag of chain tensioners that look fine to me, but it may be worth thinking about.

 

Thank you so much for the info! How about the chain guides? Is it possible to change them without pulling the chain cover?

 

You can do the top one quite easily but not the bottom, that requires the front cover and sump off.

I've never done a bottom except when I took the engine out for overhaul and it was replaced as part of the job. I am told the plastic can go brittle but I have never seen it myself.

 

I’ll put a new chain and tensioner in it, a valve adjustment and send it. They day the M102 gives up a diesel will replace it. Even though I like the M102