M271 Chain reaction.

[Oldspanners]

Been thinking about the chain problem and what the best course of action is if and when the time comes with my C180 with about 65K miles at the moment.
Change the chain with an open chain, new link and tensioner or strip the front off and use a closed chain and new guides but by going that far should you change the cam sprockets too. After all that it still leaves the crank sprocket and the chain for the oil pump.
How far to go and when to prevent any damage is the question.

 

[alexanderfoti]

It is my understanding that the cam gears are made if metal that has slipped the hardening process and as such wear quickly.

You must change the chain and that sprockets otherwise its a false economy. I believe that the lower gears are not affected and don't need to be changed.

I wouldn't change the chain only. I understand it's less work but I think you will have to do the job twice if you do.

 

[Arudge]

I would change the cam sprockets and chain.

I haven't seen these sprockets in the flesh but they look sintered to me, which would fit in with Mercedes apparent cost cutting on the day. Powder metallurgy has a lot of applications for sprockets but has no where near the wear resistance of heat treated steel. I believe Harley Davidson used to use sintered sprockets in their gearboxes, but since changed to reduce noise. I'd change them but leave the bottom sprocket alone.

 

[alexanderfoti]

Sintered parts can be heat treated after casting too.

 

[Arudge]

Sintered parts are pressed and then cooked to bind the material together. The clip below is pretty much all there is to it.
What the clip doesn't show is the fact the parts shrink in the furnace, and not a bit either, 30%-40%.

But yes, they can be further heat treated to harden or add other properties.