Yes, the plastic/nylon that support and route the chain. PN is 1160521716 for the upper three. The tensioner arm replacement liner is PN 1160520083.

Depends how mechanical you are in the end and if you have a decent set of metric tools. They are easy to me, but that does not mean for you. I would buy the guide rail pin puller, it is $40 well spent. You would have to do at least:

pull air filter assy
camshaft covers
remove belts
PS pump with backing plate
remove then reinstall tensioner

Would need to order at least:
guide rails
camshaft cover gaskets
camshaft cover crush washers
camshaft oiler tube retainers
rails and liner

I think there are some writeups on this site on how it is done and of course refer to the factory service book (it is on CD). If you are worried, I cannot imagine a shop charging more than 3-5 hours for the work. I do believe the rail swap is a great way to 'get your feet wet' as the job is not very complex.

PLUS while all apart you can check the timing chain elongation and replace if necessary. Figure about $150 for the chain and if you need woodruff keys, order THREE! Do not make that mistake I did.........



Plenum gaskets are considerably more convoluted. Think of doing an intake manifold swap on an old carb V8... but FAR more indepth due to removal of the EFI assembly and keeping all organized.

That is not for the faint of heart.

__________________
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'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

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