My 92 500E has some 96,000 miles. I have heard various comments on change intervals for the timing chains. We recently replaced them on my 380SE and simply rolled the new one in.

How complex is the timing chain replacement on the 500E. Can you roll the new one in? If so, can I or should I replace the rails as a safety precaution under the understanding that the rails are plastic and in a heated environment may have become brittle? Can the rails be replaced easily or is that complicated.

I enjoyed the guided tour on the replacement of the distributors for the 500E. Is there a similar guided tour for the timing chains.

Thanks

Dwight

Dwight;

Here's my 2 cents. THe chaing is probably OK but rails should be checked and possibly replaced. I'll let a knowledgable tech confirm BUT I's a pretty hairy ordeal... lots of labor from what I know.

I have not seen one of these just let go. I have had them towed in making alot of noise, knocking and soforth.

I would just wait for the day you hear a slight rattle on start up.

When this happens, you may want to go and get the chain, rails and tensioner done.

Yes, it is a tough job that requires special tools.

I'm getting my rails done on Monday. I got the idler arm bushing replaced today and the shop owner showed me his 1987 420SEL. Beautiful car but it has a blown engine due to the plastic rail failing. The part of the rail that extends above the head broke off and jammed one of the cam gears. This caused the chain to skip or stop, I don't know which. A couple of valves broke off and severely gouged the cylinder walls and the pistons. He said that they can't be re-bored deep enough to repair and that putting in sleeves would be rather expensive. So, he is looking for a replacement engine for several thousand dollars. If my rails show that deep brown patina, I'll know it was time for the repair. If not, I will still rest easy knowing exactly what the inside of my engine looks like.

The rails are good now. They were in poor shape. Not cracked, but very brown and brittle. The chain and tensioner were good.