Chain Jumping Teeth

Jun 28, 2003 5 Replies

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Larry 23 years ago

I just replaced the timing chain on my 380sl, and the cam marks aligned perfectly with the 0 mark on the vibration damper. However, when I was rotating the chain manually to reinstall the rockers, before installing a new tensioner, I noticed that the chain would ocassionally jump on the passenger side, and now the cam marks and vibration damper are off by app. 18 degrees, which I think correponds to 1 tooth.

Can anyone tell me what's causing the new chain to jump like this, and how to correct it?

Thanks a lot.

Larry

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T.G. Lambach 23 years ago

There was no tensioner installed to control the new chain's slack.

The right cam's lobes controlled the cam as the lobes sought to avoid opening their respective valves. The lobes prevailed over the slack chain and the chain jumped a tooth.

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T.G. Lambach 23 years ago

Additional thought, turn the engine to TDC or whatever mark you previously used to check the cams' synchrosity with the crank. That's to ensure the cam is restored to its correct position and not 36 degrees - as would probably happen to me!

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Larry 23 years ago

Thanks very, very much for the help, T.G.. After pulling the chain back, the left cam marks are aligned, and the vibration damper is at

0, but the right cam mark is still about 1/4 - 1/2" past the cam tower mark. However, I haven't installed the tensioner yet, and i'm assuming that when I do, hopefully tomorrow, it will take up the slack, and cause the right cam marks to also align. Am I correct about this, or should the left marks also be aligned, even though the tensioner isn't in there yet?

My sincere thanks again, T.G..

Larry

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T.G. Lambach 23 years ago

Good point - that the tensioner may bring the right cam to TDC.

It may be so, I don't know.

I read your first post as affirmatively stating that the cams were at TDC but then the right cam had jumped, thus my suggestion to cheat the cam back one tooth.

Install the tensioner and see how it looks, worst case the tensioner must be removed and the cheat method employed.

Tom

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FatHead 23 years ago

TG --

Amazing.

You really know your stuff.

Just a joy reading the exchange. Worth the price of my high-speed connection.

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