Timing Chain Stretch and Tensioner?

[Philoprof]

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.

[Frank Reiner]

Originally Posted by Philoprof

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.

10 deg. BTDC, or 10 deg, ATDC?

Sad to say, rotating the engine, even very carefully, and only in the direction of normal rotation, without tension on the chain, is an invitation to jump a tooth. One tooth, however, is ~20 deg.

[gear-head]

I've personally never heard of an SWS brand timing chain, but that doesn't mean much. However IWIS brand IS OEM Mercedes so you're good there. I've never heard of checking for chain stretch by removing the tensioner first. I'd have to say that's not the right way. I've always been instructed to do it pretty much just the way you said you did it, however with the tensioner in place.

[Philoprof]

Thanks for the reply gear-head. However, I also posted my message on another forum, and the discussion there has gone way beyond this one:

Timing Chain Stretch and Tensioner? - Mercedes-Benz Forum