Chain post

I've started getting a repetitive clicking sound the engine of my 380sl , particularly when the engine is cold, and I haven't been able find out where it was coming from with a stethoscope. So, I decided to check the timing chain stretch by rotating the engine until the mark on the passenger side (right) cam lined up with the mark on that cam tower, and the mark on the driver's side cam to lined up a hair-off with the mark on that cam tower, as I believe it's supposed to.

However, I was surprised to find that the harmonic balancer was at app. 10 degrees when, IIRC, it should have been at zero, especially because I replaced the double chain less than 100k miles ago, and I change the oil every 3K miles

So, before I change the chain again, I was wondering if:

(1) My having removed the tensioner before I rotated the engine and checked the stretch could have had anything to do with the chain being 10 degrees off,
(2) It's possible that the IWIS chain I used somehow stretched more than an OE chain would have; and if
(3) Anybody here has ever used a chain made by SWS.
Thanks very much in advance for the quick responses, since my car will be sitting in my garage until I am confident that I can fix it properly.

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Bill
1981 380sl

chain stretch can't be accurate if the tensioner is missing. reinstall it and try again. good luck, chuck.

From what I have heard the IWIS chain is what you will get from the dealer, just with the dealer mark up.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

I have never checked chain stretch with the tensioner out.

IWIS is top notch stuff, I have used them with great success in all of my vehicles. Even with a new chain and new rails in the 560, the cams were still about -1° late... tossed in some +2° woodruff keys. Now they are +1°, I figure the chain will elongate and I will be fine.

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I'm not a doctor, but I'll have a look.

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

Six others from BMW, GM, and Ford.

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Thanks very much for the fast and informative replies. I ‘ve posted pictures of the right and left cam shaft marks and their tower marks, as well as a picture of the harmonic balancer mark, showing that it is approximately 10 degrees off.

As it turns out, I thought I had removed the tensioner. But I only loosened the bolts slightly to see how difficult removing them would be. So, the tensioner is still putting its regular pressure on the chain.

At this point I’m assuming that the prudent thing to do would be to change the timing chain, but I’m still wondering whether I need to change the tensioner and its rail, considering that I change them when I changed the chain less that 100K miles ago, and AFAIK the tensioner rail doesn’t break? OTOH, since I replaced the two plastic, top rails, which I’ve heard are most prone to breaking, with metal rails at that time, I’m assuming that they’re still good.

Since I’ve already removed everything that needs to be removed to replace the chain, I’d hate to have to put everything back together to drive it to an Indy for him to replace it, and I’d also hate to have it towed there. But I’m afraid to replace the chain myself, considering the problems that screwing the job up can create. So, I was wondering if that’s something I can do alone, considering that I’ve done a lot of other stuff before.

Any additional help would also be greatly appreciated.

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Bill
1981 380sl

life expectancy is aprox 100k on any chain, including oe mercedes. replace the chain, tens and rails-all 4. i replace them anywhere after 7 when i see them. 10 means it may jump a tooth or 2. good luck, chuck.

I think the chain tensioner would have no impact on chain stretch measurement. The chain is tight on the pulling side. The tensioner just takes up slack on the backside. I had a tensioner fail on a 240D - ran fine until the chain double wrapped around the crank sprocket and broke.

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1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold