6.9 chain tensioner replacement vs rebuilding

[s class]

I bought one 6.9 chain and tensioner which I fitted to the AMG. The tensioner in particular was rather expensive. I'm now faced with repeating this job on trusty rusty.

I have stripped and examined the old tensioner that came off the AMG and I really cant see any reason not to reuse it. In the interests of thoroughness, I would however still replace the tensioning spring and rachetting circlip - I believe these are available separately from Mercedes. With those two items replaced, and the unit reset to the assembly position, it seems to me it should be as good as new - or am I missing something?

 

[WGB]

I have heard on the M-100 site that there is a serviceable item in this tensioner but otherwise they are re-usable.

I will be awaiting any replies with anxious anticipation as I willbe in the same boat.

Bill

 

[Styria]

Hi guys, I really cannot see any reason why the tensioner would ever wear out. The only item of concern would appear to be the steel sealing ring that could wear out the bore of the tensioner body, but I reckon you'd have to do a million miles before that would happen. Regards Styria

 

[s class]

thanks for confirming my opinion styria. I think that for trusty rusty I will pick the best of the two (the original ones from each of the two cars) for the time being, and if I ever go to the expense of rebuilding the engine, then I would probably fit a new tensioner.

 

[s class]

On a related vein, I have stripped the tensioner of my 450SL - this is the early cast iron one with separate closing cap. Apparently the later alloy tensioners are not serviceable. Anyhow my 450SL's tensioner has gone 'soft', and I can see only two possible causes for this - loss of temper of the spring, and wear in the rubber o-ring in the bore (the 6.9 unit lacks the o-ring). Again, it would seem logical to me that if the o-ring and spring were replaced, it should be serviceable. Anyone have experience or opinions on this?

 

[WGB]

I just remember how soft and floppy the old tensioner was on my 450 motor vs the tightness of a new one and that the cost was not that bad - about AUD$150 from memory.

I have just ordered a new 6.9 timing Chain and tensioner from Tom Hansen at the Classic Centre in Irvine California and with the 15% discount for M-100 members the chain is US$105.40 with link and the Tensioner is US$189.60 with gasket.

Seems pretty economical peace of mind to me.

Bill

 

[s class]

Bill, those prices from the classic centre are competitive. I think I will go that route when I get another 6.9 chain for trusty rusty.

 

[Styria]

Hi Bill, when you get the chain, any chance of letting us know the brand - I am really curious what MB supply. Regards, Styria

 

[WGB]

I'll let you know Styria - but as far as I know they usually use IWIS.

Bill

 

[s class]

I recently bought chains for the 4.5 and 6.9 from the dealer, and both were IWIS.

 

[s class]

Today I partially stripped a scrap M110 I had in my garage. I thought it may be of interest that the tensioner is very similar to the 6.9 in design, though the parts are slightly larger in diameter than for the 6.9, and so are not interchangeable. The M110 tensioner is entirely housed in the cylinder head, thus eliminating the need for the separate flange that the 6.9 uses.

The M110 tensioner is also apparently ratchetting in design. I will hopefully take some pictures tomorrow.

 

[WGB]

Hi Bill, when you get the chain, any chance of letting us know the brand - I am really curious what MB supply. Regards, Styria

My new chain and tensioner arrived today from the Classic centre. I was surprised that it had arrived so quickly as they said there was a delay.

Yes Styria the chain is an IWIS and it has the single clip joiner.

Bill