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tahodgson 03-19-2000 05:53 PM

I'm new to Benz ownership, buy my 1987 560 SL isn't new...about 101,000 miles. Have heard scuttlebutt that this is the time to have the timing chain checked. The car has just recently begun to run a little rough...and I haven't yet gone over the ignition system.

Please give me the straight scoop on the "Timing Chain at 100,000 Miles" ledgend.

...and confidential to Benzmac...was in Atlanta last week...should've stopped by and bought you a cup (or bottle) for all you do for the folks here in this forum!

pmjs 03-19-2000 06:20 PM

at 101k miles either your a lucky man or most likely the chain has been already replaced earlier.the chains and 4 upper rails are in need of replacement usually at 6ok,like clockwork.Recommend removal of both valve covers for inspection.what happens is the chain stretches and then slaps the chain rails.this can happen at start-up and while driving.rather be safe than sorry,have it checked.rec replace chain tensioner too

[This message has been edited by Webmaster (edited 03-20-2000).]

stevebfl 03-19-2000 06:42 PM

I have overseen the repair of at least 200 single cam MB V8 chain failures (3.5/4.5, 3.8/5.0, 4.2/5.6).

Here is the story; The number one cause of failure (9 to 1 atleast)is the fracture of petrified chain rails. The rails in the upper head do not normally touch the chain. When they are new they are opaque white plastic. They are indestructable. After 70-100k they turn brown and become as brittle as glass.

Now comes the sweet part; even with various tentioners and modifications MB could never 100% not loose the oil pressure in the tentioner. They just rattle every once in a while. Its a shame they never put a ratcheting tentioner in, but I'm sure they had their reasons. This rattle (you can't prevent it) breaks the old rails like glass and the pieces run through the meat grinder bending all the valves in the left head. Just like clockwork.

My recommendation is new rails every 60-80k. It is only about a three hour job and the rails are less than $5 a piece. Do a chain if you want but it won't fail on its own. After 150k you will have about 10deg retard in the passenger side cam due to stretch but we used to use offset keys to tune that out. This is factory method they couldn't have been too worried, originally. Thus my total recommendation is a chain before 200k and as many rails as necessary to keep them fresh.

Now for the second life. The bottom right side rail rides on the chain and will wear through at around 300k; so if you are in the neiborhood with head work or chain repair take that into consideration. This rail requires removal of the front timing cover about an extra 12-15 hours work with a head job. About 20 hours or more on engine with the heads on. We charge 40 hours to do heads and front timing cover on 107 SLs where the subframe and oil pan must be removed.

Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician 03-19-2000 06:51 PM

I just bought a 1991 300D with 160K on the clock. Before I begin to have nightmares about the timing chain, what is the scoop with the timing chain on my little diesel?
Again, THANKS for all of the time everyne has put in here answering my questions.

mbdoc 03-19-2000 07:06 PM

Diesel chains are stronger than the gas models, but 160K miles is long enough. Don't put off replacement. 03-19-2000 07:57 PM

I ahve all the records for the car, but I do not see anything with regards to inspecting/replacing a timing chain. Do you know what MB recomends to inspect/service the chain? Do you knwo what it should cost (roughly) to replace this?

Robert W. Roe 03-19-2000 08:55 PM

I had my mechanic check my timing chain stretch. He measured it at 3 degrees and said 5 degrees is replacement time. With 169K miles on my M617 diesel, how much time do I have left?

Robert W. Roe
1984 300SD 169K mi 03-19-2000 09:02 PM

When I take my car to the mechanic on Wednesday, is this measurement procedure something that can be done why I wait?

chaudo 03-19-2000 09:20 PM

This is an interesting topic. I have a '90 300SL with 190 K. I recently brought it to a MB dealer and enquired as to whether the timing chain needs to be inspected and was advised that it there was no need for this service.

Given all of the problems and advice that I've read in this forum, why is MB so stubborn about insisting that that timing chains service is unnecessary?

Also, I need to repair my AC. Does anyone know of a reputable independant MB tech. in the Toronto, Canada area? I would appreciate any recommendation because I am not entirely convinced that I am getting value for the service provided by the dealer. Lastly, does anyone have any experience with non-OEM AC parts or rebuilts for an AC, if such parts exist? 03-19-2000 09:33 PM

I know that there are several reputable MB techicians that monitor this site, let's see what they have to say. So far they have been right on all of my other questions.

Aaron 03-19-2000 10:55 PM

I don't know if any of you saw one of my more recent posts, but I just had to do a new chain and all upper rails on my '85 380SE. I had been experiencing a rough idle for some time. I replaced everything in the fuel injection circuit and still no avail. Finally, when I had the day off from the shop, I decided to pull the valve covers because I was suspecting the left cam of not being timed properly. Sure enough, the left inner rail was broken into pieces! I was sooo lucky that it didn't destroy my engine, but I caught it right in time. Car has 110K miles on it and as I am writing this, I am on vacation in Atlanta, GA and drove the 380 here and it ran beautifully all the way at am average 85-90mph loaded down with luggage and four people. In the meantime, my 420SEL is still sitting in the stable at home awaiting major top end work, because the same thing happened to that car but unfortunately I wasn't so lucky. That car has 102K on it. Will be pulling the heads as soon as the weather breaks.

Aaron Greenberg
MB technician
Precision Motorcars, Cincinnati, Ohio
'67 250SE Cabriolet
'77 450SL
'80 300SD
'85 380SE
'89 420SEL
'93 300E 2.8
'74 Jensen Interceptor Mk.III
'81 DeLorean DMC12
'85 BMW 745i Turbo

elau 03-19-2000 11:03 PM

I have a 95 SL320 with 64K miles, do I need to take it in and have my timing chain looked at? Someone told me the newer SL has two rows of chain and there is no requirement to change them ever. Can someone clarify this for me?

95 R129
98 ML320 03-20-2000 06:40 AM

I think we need a great deal of clarification on what cars have what and when.

LarryBible 03-20-2000 07:47 AM


If you do get a chance to get Benzmac a cup or bottle, send me the bill.


tahodgson 03-20-2000 09:01 AM

Well, I'm now almost afraid to drive it to the shop...but I'm certainly going to take it in. One good thing...I haven't noticed any strange noises upon start-up...but also admit that I haven't had the car long enough to learn it's "normal" sounds. (bought in November and almost immediately stored it until a couple of weeks ago).

Thanks, everyone, for your great advise and counsel (again).


'87 560 SL

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