I am taking my 85 500 SEL with 109k to get the chain replaced along with the guides. I have searched this remarkable site and read every possible thread on the subject ((Something everyone should do before firing off a question)). So I know I am on borrowed time. Other than occasional rough idle (chain slack/O2 sensor?) the car is a dream!

Unfortunately I am moving shortly, and will be leaving my trusted independent mechanic behind. So I am having him go over the car and prioritize "anticipated" future needs.

My question is:
What about after the replacement? Are there things I should look for. Should I do an oil change shortly thereafter? In the past, solving one problem may have highlighted another, which was then taken care of. In this case I do not have that luxury. If replacing the chain and the O2 sensor do not solve the idle problem then where would you look next - fuel delivery, injection?

Danke

Does anyone know why this timing chain replacement should not take place? Speak now or forever hold your peace. Good luck.

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1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T

Hmmm,
I believe you have the single chain. I've heard that
it can be disasterous when this goes out.

Remember, bad things only happen at the worst times.

Gary

If you are converting from a single to a double chain, it can be quite involved. I just did one myself on my 380sl. I will be glad to give you the details if you e-mail me. If, on the other hand, you are simply putting a new double chain in where a double chain already exists, it is a matter of only rolling in a new chain. No problem and very simply process. It should not be expensive as it only takes an hour or less. The upper guides are very simply to change also (not the lower ones down inside the front cover, that is a lot more involved).

That's right, all of the 500 series cars had a double-roller chain. They learned a lot from the US version 380 .
I can't think of anything that the chain replacement would cause a problem with...
Good Luck
Randy D.

Actually, Mercedes had double chains on all of the SL's except the US versions from '81-'84 (maybe '85). They really did not learn anything from this, they knew all along that it was not a good idea. M/B actually converted a few under warranty a few years back.

Thanks all for the feedback.
It has not escaped me that we are doing this on Friday the 13th !!

The car is the US version (84/85 years only). She is loaded with I believe every option they had at the time - ABS, Air bag, and I even have the privacy curtains.

I am expecting double chains, but will know for sure this weekend.

Your 500 has a double-row chain. The only V-8s afflicted with the single row chain were the '81-'83 US 380s. They reverted to a double-row for 1984. Be careful about the brand of chain you use; MB or IWIS seem fine, but one of the other brands (which I can't recall) seems to have caused at least one report of premature stress cracking. Given its importance, a replacement chain is not all that expensive, so get a good one.

You might as well change the oil while you're at it. Don't worry about breaking in the old stuff (still chuckling over that one). The rough idle could be a number of things: a faulty O2 Sensor is a possibility (although if the engine idles unevenly when cold, it probably isn't the O2 sensor), but it could also be an ignition system problem (even using platinum or incorrectly gapped spark plugs has been known to cause idle problems), warm up regulator, idle speed controller, etc. etc. etc. Many of these components are rather expensive, so you should try to arrive at a reliable diagnosis before you begin replacing parts.

Old Blue, regarding the idea of changing the oil shortly after replacing the chain is an excellent idea. Most mechanics are not too particular about keeping things sterile upon removing a valve cover. After a tank of gas I agree with you that a change would be helpful in removing any road grime that falls onto the inside of the head. Also, you may want to get an air hose and blow what dust you can from around the head area before you do the job. I usually oil the chain first by using an old sprocket from which to hang the chain down into a cut open bottle of oil. Rotate the chain a few revolutions to get good oil penetration. Tell the mechanic up front that this is what you would like to do and then watch him. (I have been disappointed in the hygiene habits of mechanics more often than not)

Old Blue:
I had a 56 180d named old blue.It sounds like you're in good hands with your mechanic. Change the chain and rails especialy the left bank. I also recommend start using Chevron Supreme to keep the injectors clean.Don't get me wrong:I dislike all oil companies,but techron does work.

Peter

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Auto Zentral Ltd.

It's official - dual chains.

We replaced both chains, and all accessible guides, plus the main gear. The teeth were worn to pointed tips instead of flat. I did not read any past posts about this, but suspect for $30 it is a good idea.

Also replaced the O2 sensor, some oil filler tubes, and a few misc. items.

End result - smooth and tight, with no more vibration. I am hoping to get some better gas mileage with the new O2 sensor .... time will tell.