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When is it time For a new Chain?

Started by 500eguy, 06 November 2007, 04:46 AM

Andrew280SEL

Well there's certainly no noises when starting up, ever. So I don't think there's a valve problem. Timing should be right, it was only checked and set a matter of weeks ago.

But yeah, I'll have to drive it again and see.
'79 280SEL- 560,000 Kms
'73 350SE- getting an AMG facelift
'79 450SEL 6.9

WGB

The only real way to check a timing chain is to remove the right cam-cover and check the colour of the plastic "sliders" and the amount of chain stretch. The cam cover is quite easy to remove after removing the air-cleaner and has a re-usable rubber gasket which will hopefully be in good condition (just don't tighten the holding bolts more than recomended when replacing it).

The sliders are milky white when new and slowly go from tan to dark brown as they age and become more brittle.

The chain is checked by setting the TDC marks on the right hand Cam tower by pulling the motor through with a socket and bar on the crankshaft pulley Bolt and then seeing how many degrees after TDC there is on the crankshaft pulley. Maximum stretch is 11 degrees as far as I am aware on a 117 motor - assume a 116 is similar.

While you are there you will see the tensioner slipper and can see if there is sufficient static tension to enable a safe cold start. This - I believe - is the actual major failure causer in the whole system.

The other 116/117 weak point is that the oiling tubes over the camshafts are joined by little plastic connectors. These are dark brown from new (unlike the sliders) and can become brittle with age and heat. The set I purchased for my 117 motor cost $12 - three years ago.

That is the only way to know what you really have under the hood.

Bill

dudu

Example...

This is what i found when i opened my cam covers.... ( oiler tubes were not fixed , but hopefully still working... )...



It took 15 minutes to clean them and replace for a new ones... at the same time we worked on the valve adjustment ( using a crowfoot ) ... and also worked cleaning the cam covers that were very dirty due to "fried" oil... may be previous owner did not take care of the car as it should... :-[

Regards.