Can I follow the advice for checking Diesel timing chain stretch on an M103? If so, what is the allowable strech on an M103 in crank degrees?

Thanks,
Sixto
91 300SE

If the engine has been somewhat maintained, it shouldn't need a chain. I have only replaced two in ten years of working on these engines.

I would allow for 5-8 degrees of stretch on this one, but you will not find that much.

(8 degrees is only 2.5% of crank rotation. ON a gas engine, that is nothing)

[Edited by Benzmac on 07-03-2001 at 09:53 PM]

Donnie had to point out to me about a year ago that these have a ratcheting tensioner. Because of this, it is pointless to replace the chain for preventive maintenance reasons.

Have a great day,

Larry,

Please explain further:

1) Does ratcheting mean that the tensioner adjusts its 'soft' setting as the chain and guides wear?

2) Why does this feature make it pointless to replace the chain as a preventive measure?

3) Does the tensioner maintain cam timing? I can't see how this could work without a tensioner on the other side of the chain as well.

4) <off topic> How does cam timing adjustment work on an M104?

Thanks,
Sixto
91 300SE

The ratcheting tensioner engines just have a history of chain reliability.

Even if the chain wears a good bit, it will not change timing to a detrimental level. Chains are typically not changed because of their effect on timing, but because of their threat of breakage.

I expect that the ratcheting tensioner maintains a tight chain thus preventing slack at any one time. If the slack is allowed at various times a whipping efffect imposes impact loading of the chain.

Have a great day,
Larry