Stumbled onto possible problem...rattle on cold start - PeachParts Mercedes-Benz Forum

RickM · #1 07-19-2004, 10:23 AM

OK, here I am looking for tips on an easier oil change and stumble onto a possible problem.

Recently, I noticed a short rattle on cold starts. Kind of sounds like the fan blade clacking against a guard for a few seconds. Now I read about timing chains and/or upper/lower guards. Some say after replacment the noise still persists. Uh boy.

Any advice on what it most likely is? Also, any easy to follow checks and or repair procedures on my 1985 380SL?

Thanks!

DavidSoine · #2 07-19-2004, 01:47 PM

Typical symptoms of failing Cam Chain tensioner...

best,

Dave

RickM · #3 07-19-2004, 01:54 PM

David,

Thanks for the reply. Could you give me a quick rundown on replacement. High level, nothing too detailed unless you have a link to a tech article or the time.

Thanks

DavidSoine · #4 07-19-2004, 03:29 PM

Very simple remove and replace (2 bolts) on my V8..."tool access" was a challenge, I had to move a couple other things out of the way. Located on the front edge of the block/timing cover.

Go to Fastlane to get a look at the part, under "Engine mechanical" "timing chain tensioner".

best,

Dave

cwmoser · #5 07-20-2004, 08:09 AM

How does th timing chain tensioner fail? I assume it puts tension on the timing chain to keep it snug so it must have a spring. Does the spring break or does the tensioner just get gummed up with sludge?

CW
www.380SL.8k.com

Quote:

Originally posted by DavidSoine
Very simple remove and replace (2 bolts) on my V8..."tool access" was a challenge, I had to move a couple other things out of the way. Located on the front edge of the block/timing cover.

Go to Fastlane to get a look at the part, under "Engine mechanical" "timing chain tensioner".

best,

Dave

DanielG · #6 07-20-2004, 10:20 AM

CW -- I just spent some time at your web site -- very nice, good tips, good information. Your car is beautiful. Thanks for sharing.

ctaylor738 · #7 07-20-2004, 10:40 AM

There is a check valve in the tensioner that is supposed to retain pressure after the engine is shut off. If it goes TU, then pressure is lost and it takes a few seconds to build back up and tension the chain.

You should get this attended to pronto. The instant when the engine starts and RPMs go from 0 to 600 in a second or two is a very bad time to have the chain flopping around.