[W126 Coupe] timing chain question

[Richard Hallberg]

I think he quantity and quality of mileage on the engine should be 
factored in to replacement decisions.  The bottom line is a careful 
inspection for wear on the sprocket teeth and valleys along with the 
resultant valve timing reading after the new chain and/or rails and 
tensioner are fitted.  The drive sprocket is bathed in oil and, I 
suppose, should wear far less than the cam sprockets.  A corollary is 
written and verbal recommendations I've received of not replacing the 
lower chain guide rails with each new chain as they also are well oiled 
- and are much more labor-intensive to access.  These will be my 
considerations, along with consultation with Jonothan Hodgman, when it 
is time to do the chain on my 91 560 SEC.

Richard

Josh Allen wrote:

> Attila wrote:

>>

>> Has anyone replaced the crankshaft gear, when

>>

>> doing a timing-chain ?? We plan on doing both

>>

>> camshaft gears, but not sure about the crankshaft.

>>

>> Is it a good idea as a preventive measure ?? This

>>

>> is an ’89, 420SEL, with around 180k miles. Thanks.

>>

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>>

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> I know I left the sprockets in place on my 500SEC when I replaced the 

> guides and chain, but I saw no signs of wear on the cam ones, and 

> they'd be the first to show wear due to the smaller size.

>

> I'm not sure just how necessary it is thought to be, though.

>

> -Josh Allen

> The MB Coupes Website!

> W126 SEC Mailing List

> Postings remain property of MB Coupes, L.L.C.

>

>