Timing Chain Upper Guide

[mototools]

Hello Diesel Forum,

My 93 300SD is making a thwacky/clacky sound near the front of the engine, and since it has traveled 153K miles I decided to inspect/change the Timing chain. On visual inspection all looks well, but I noticed that the upper timing chain guide has 1/8-inch lateral play (sliding on its mounting pins), and if you give it a poke it will make a clacky sound when it bounces back and forth.
Question: how much play is normal?
I purchased a new guide with the chain so was planning on changing it.
Question2: How are the Guide pins located and secured?

Thanks,

Rob Little

[billrei]

You want to check chain stretch which is detailed in the Mercedes Workshop manual, available on a CD. Check eBay. As the robot said: Warning! Warning Will Robertson!! danger lurks for those who venture into motor without proper documentation...

[sixto]

Are you sure it's not the belt tensioner shock?

Sixto
95 S420
87 300SDL

[mototools]

Originally Posted by sixto

Are you sure it's not the belt tensioner shock?

Sixto
95 S420
87 300SDL

Hi Sixto,

I replaced the tensioner shock first (upper bushing shot)and that did eliminate some of the rattle, but other rattle(s) remains. I also have run a can of Moly Lubro through the injectors.
The upper guide definately makes the type noise noise I am hearing if you snap it back-and-forth on its pins, but maybe this noise is being drowned-out by another noise when the engine is running.

I measured the chain elogation and it was 2 1/2-deg (within specs) so I buttoned things up. Maybe a italian tune-up is all she needs.

Rob