On most MB engines, Arthurs recommendation would be valid, but not on the 103. This engines timing chain system is simple and bulletproof.

Marking the chain as it relates to its cam sprocket position may get you in trouble. If it were to slip on the crank sprocket during the process, you would be out of time. One notch retarded will make the engine run bad, one notch advanced will cause piston/valve contact!

Before removing cam sprocket, turn the engine to TDC as marked on the harmonic balancer and then remove the chain tensioner. ONLY THEN should you remove the cam sprocket. Use some wire to hold the chain and have someone feed the chain and wire through the head then tie the wire off to hold the chain and keep it from dropping in the cavity.

When reassembling, put the camshaft in position on the head with the timing marks at the top of the front cam bearing stand aligned with the cam mark. Tighten all the cambearing stand bolts and rocker arm stand bolts down evenly across the head. Tightening one stand all the way without slowly running all of them down a little at a time can break the cam and strip the bolt holes.

Once the chain is back in place and the cam and crank are properly timed. Push the toothed plunger in the tensioner all the way through and out. Then start it back through slightly. When the engine starts, oil pressure will push the tensioner to the proper position. Failure to do this can cause serious problems.

Good luck,