PeachParts Mercedes-Benz Forum - View Single Post

tcane · #4 01-16-2002, 10:37 PM

You check timing chain stretch using the following procedure (for a non-turbo 300D, you'll need to get the specs for you turbo):

1. remove valve cover
2. adjust #1 intake valve to 0/zero clearance
3. mount a dial gauge so it contacts the valve spring cap at a
perpendicular angle (or as close as you can with a
preload of greater than 2mm, 3-4mm is best)
4. turn engine to TDC #1 cylinder
5. carefully continue to turn engine until #1 intake valve opens
2mm
6. read the degree marks on the harmonic balancer

On the non-turbo 300D a new timing chain will show 11.5 degrees ATDC (after top dead center)

A chain with 20,000 km or more will show 13.5 degrees ATDC

M-B uses/sells offset woodruff keys to adjust cam timing for used timing chains in good condition, offset woodruff keys come in 4, 6 1/2, 8, and 10 degrees of cam timing (cam turns at 1/2 speed of the crankshaft)

You cannot use the notch in the cam washer and the timing mark on the cam support/bearing to determine how much chain stretch you have. These marks are used to assemble and time the engine when assembling it and/or replacing components and the crankshaft, cam, injection pump or the IP timing device have been moved and everything needs to be re-timed.

Your turbo 300D uses a similar method to determine timing chain stretch (and from what I've read in the Tech Forum and at the library a lot of the M-B gas engines also use the above procedure to check chain stretch). What I do not have is the degrees ATDC specs. for your engine. Perhaps one of the other members has this info and will share it with you.

Good Luck!
Tom