How to check chain stretch on a 603?
 

I have been doing searches on how to check the chain stretch on my car, but haven't come up with a definitive answer. Can anyone describe the proceedure for doing this? I have a new chain to go into the car, but am having second thoughts about changing it if it's not necessary.

The eyeball method is to align the cam TDC mark with the pointer on the #1 cam bearing tower, then see how far off the crank pulley TDC mark is from the pointer on the timing chain cover. Take several readings to be sure.

The FSM method is more precise but also more complicated. Requires measurement with a dial gauge and 2mm of valve lift or something like that.

Sixto
93 300SD

I did the eyeball method, tried it a few times to see how close. It was about 2-3° on mine.

First purchase a FSM.

Try this
 

http://mb.braingears.com/124_DISC1/Program/Engine/602_603/05-6015hw.pdf

You'll need a dial indicator.

Check out this thread in the MBCA forums. Dr Booth has attached the TSB.

Basically you will have to remove the charge air pipe, the valve cover, and the fan, and probably the belt. Rotate the engine using the crankshaft nut (don't rotate it backwards!) until you line up the mark in the top sprocket as shown in the TSB. Read from the dial down at the crankshaft. You may need to clean up the dial a bit with a rag (taking car not the move the indicator) and it will be easier to rotate the engine if you pull a glow plug or several. Rotate the engine through several times to verify your reading. If you don't line up the mark on the sprocket with the indicator then your reading can be way off on the dial. While you are rotating through you should check for wear as shown in the TSB.

In the attached picture you can (just) see the score in a the top of the sprocket and the nub that you line it up to. It is actually aligned in this picture, but I had to take the shot at an angle so it doesn't appear so.