Timing chain-when to replace it?

[rowdie]

Yes. When I did the '73 I checked the tensioner from it against the one on the '72. The '72 had a lot more tension. Since both engines had marks inside the head from chain slap I decided to not take a chance and bought a new one. The new one had twice the resistance of the best one I had.

[meltedpanda]

the tensioner requires the same amount of dismantling as doing the chain correct?

[450slcguy]

Originally Posted by meltedpanda

the tensioner requires the same amount of dismantling as doing the chain correct?

Assuming your talking about the chain tensioner, a couple bolts and it's out. Maybe 10 minutes. The new one will be stiffer and will require some persuasion to bolt back on. Pretty easy job. But then again, sometimes the easiest jobs are the hardest.

Now the tensioner rail is a different story. That will require removing the alternator, valve cover, pulling the pin, removing the camshaft sprocket, and then fiddling around with the chain to gain access. Aligning the new rail with the pin can be a PITA because it's done blindly deep inside the head.

[meltedpanda]

oh really, where and how accessed , do you have a link ( no pun ) you could point me to??

[450slcguy]

Originally Posted by meltedpanda

oh really, where and how accessed , do you have a link ( no pun ) you could point me to??

On my engine, 117.985, manual say's to remove right exhaust manifold and pipe. I have no idea why they would suggest that, as access to the tensioner is not an issue and quite easy.

On your engine, they suggest removing the upper engine shock mounting bracket . Maybe yes, maybe no. You'll have to see what access you have to get at the bolts. I believe the early tensioners such as yours can be rebuilt by removing the large hex nut on top of the tensioner and swapping out parts. Might be easier to just but a new one as it's not that expensive and alot easier.

chain tensioner.pdf

Sometimes I think the MB manual is designed to pad the dealers repair bill. It is an invaluable guide undoubtably, but don't take everything it say's as gospel. Sometimes the recommended procedures are quite vague, leave out steps or add in steps that aren't required. Example... The procedure for swapping out the upper chain guides doesn't even mention removing the camshaft sprockets, but it's just plain impossible to do without that step. And thats a real BIG and vital part of the job.

[meltedpanda]

thanks, this for me is knowledge for the future, I dont see a need to do it now, everything seems fine, no slap , noise, but my luck, next time I start it ........lol
thanks. and thanks for the PDF

[coleyjf]

Hi all

Just looking at some other stuff and came across this in wikipediawhich I think puts the point quite distinctly:

"Next was the 380 SL imported from 1981 to 1985. The 380 SL was the least powerful of the US imported R107 roadsters. This engine came with a single row timing chain. These models were plagued with chain failure problems and the problem was corrected by Mercedes-Benz, free of charge. Some models, however, escaped retrofit and may at some point fail as a result."

So only 380's and only pre 1986 and only if not already done

Cheers

Jim

[rowdie]

Jim.

I seem to be disagreeing with you at every turn right now. Sorry. They are all susceptible to timing chain failure. Usually due to worn or broken upper guides and or tensioner. This is a picture of a '72 450SL where the timing chain was slapping in the head. My '73 was the same way. I have heard of failures on 560SL's as well.

Jim

[ragtopper]

My 82 380 has the single-row chain. After purchasing the car a few years ago (79K miles), I was extremely nervous after reading all of the warnings of the single-row chain. I approached my trusted mechanic and he told me he had witnissed as many double-row failures as single-row, and advised me to just replace with another single row. (BIG difference in cost).

He did add that it would need to be replaced again after about 40 - 50K miles. Since I only put about 2K miles/year on the car, I opted for the cheaper route. But I do have ears wide open every time I start it....

So far so good.

Ragtopper
1982 380SL

[rowdie]

MB experimented with the '81-'83 380SL in the US market. I guess they figured with the lower compression and and such from the Euro 380, they tried to save a few bucks on the TC and gears. Didn't work out so well so they went back to the double row in '84.

[coleyjf]

Originally Posted by rowdie

Jim.

I seem to be disagreeing with you at every turn right now. Sorry. They are all susceptible to timing chain failure. Usually due to worn or broken upper guides and or tensioner. This is a picture of a '72 450SL where the timing chain was slapping in the head. My '73 was the same way. I have heard of failures on 560SL's as well.

Jim

No need to be sorry - just passing on info as I see it. In the UK/Europe (especially with the 300SL) I had never heard of any common problem with timing chain failures and as it's a 300SL that Dave has bought and had asked the question about in the first place I thought that this would be useful info

Cheers

Jim

[rowdie]

I think we all agree that the 300 in line six does not have a problem. I have heard that the DOHC M110 six needs to be checked but not as often as the V/8s. Both sixes are fantastic IMO. I need to find a 280 5 speed that needs an engine.

[meltedpanda]

wish there was a quick and easy way to check chain stretch

[rowdie]

You might try this.
http://www.peachparts.com/Wikka/M117TimingChain