Timing Chain Replacement on My 560SL
 

I thought I would post some pictures of the timing chain replacement project that I did on my 560SL. I had completed the guide rail and tensioner arm replacement first. These pix show the preparation and attachment of the new chain to the old, and the attachment of the "chain loading" tool which prevents chain jumping during roll-in.

These pictures show the roll-in process. I removed the tensioner and spark plugs before starting. I also removed the fan and shroud so that I could manually rotate the engine with a 1/2" drive ratchet, extension and 27mm socket. I put a pipe on the handle to give more leverage. The chain loading tool worked well. I had to keep both "in" and "out" chains taught so they would not bind in the sprocket. I did not remove the cam followers (rockers). This leaves tension on the cam and sporadically causes it to "jerk" during the process. The loader kept the chain attached to the teeth. If you don't use a loader, you should use a valve spring compressor and remove the rockers, or chain skip can easily occur. When I finished, I attached the ends using the master link. After installing the new tensioner I rotated the engine a few times and brought the crank to TDC. The timing marks on the camshaft lined up perfectly! Wow, time for a brew!

I also replaced the plastic parts on the cam oiler. Takes some gentle tapping with a rubber mallet to completely seat the parts.

Timing chain replacement etc...
 

Good shots, it gives one a much better idea as to what transpires during this operation. I wish I could have been there to observe. I too would like to do my own but unfortunately don't have the nerve. Were the tensioners and guides an equally trouble free install for you?

Thanks for the compliments on the pictures!

The tensioner and guides were not trouble, but there are many steps, and you need some specific tools. Depending on your mechanical experience and skills, I would rate it an "intermediate" do-it-yourself job. I read a lot on the forums, got lots of advice, and purchased a booklet from **************.com called "Preventing Catastrophic Failure on Mercedes V8". It had a lot of tips. I also have been doing mechanical work and restoration of cars (as a hobby) all my life, so I have developed many skills and have lots of tools. There is also a website called pindelski.com where you subscribe and get lots of illustrated articles. I have read good things about it. I did not subscribe as I also have the engine shop manual.

Before you can get to the guides the alternator and power steering belts need to be undone. The alternator and bracket (with cruise actuator) needs to be unbolted and moved aside. The distributor harness and cap need to be removed and the distributor needs to come out. The power steering pump and the bracket behind it need to be unbolted and moved aside. Ther are three gas line fittings that have to be undone on the left side so the flex lines can be moved off of the left camshaft cover. With the covers off, you then tackle the guides! The "jack type" pin puller from Zdmak worked nicely to remove the pins on the upper guides. Lots of other little details you work out as you go along. Working methodically, and taking your time helps. You don't want to drop stuff "down the hole". See my earlier post on guide rails.

I probably will sell the booklet and rail pin tool as I do not plan to use them in the near future. Same for the chain loader. Rather someone used them than having them sit around in my garage.

How many miles were on the old chain?
I've read a lot about folks needeing to change the chains at around 100k. The 560SL I bought has 91k on it and no noise coming from the front.
I'm familar with changing the chains on several GM products, but the only time you would need to change them is for performance reasons. ie, bigger lift cam so stronger valve springs, thus stronger chain, but even then its pretty much a 1 time thing. Heck my GN had a plastic gear originally and it still lasts over a 100k in most cases.
Why do these chains need replacing so soon, especially since its already a double roller, those should normally last forever in most GM models I know?

Great shots BTW, I didn't know the job was so involved on these, thx for the info.

Yeah, it's nice to see pictures of this. It's not easy to do a job and still take the time to photograph it each step of the way. That's waht makes this forum so great.

I'm glad to share the benefit of the pix.
My car had just over 80K miles when I did the chain. I started out to just change the upper plastic chain guide rails. They are the weak part of these engines after about 75K and 18+ years. The nylon plastic gets brittle from age and a piece can break of and get between the chain and sprocket causing chain slip. With an "interference" engine, the valves will then hit the pistons...very bad. The chain on these V8's is quite long, well over 6 feet. Normal wear of the pins in the timing chain cause chain "stretch". This could aggravate the break of a guide rail by "slapping". The stretch also puts the valve timing off. When I had my covers off I measured my stretch to be about 5 degrees on the crank. Advice from others on the forum was to change the chain while I was in there. Not a bad job, and $95 for the chain.

alkraut is giving some good advice. here are a couple of pics of broken chain guides and the result, all 4 exhaust valves on the right bank kissed the pistons lightly. the engine was stopped immediately and we got away with replacing 4 valves and all of the lower end bearings but at least everything else was OK. this was at just under 100k and when the top of the guide broke off the chain only jumped 2 teeth on the rhs cam cog

Wow a 6ft chain! I did not know that, I can see where a little stretch in a 6ft chain will add up quick to alot of slack.
The way my step-daughter drives, she'll have another 100k on the car in no time, guess this is something else to consider when she takes it in for some maintenance I don't have time to do...luckily she used to work for a MB repair shop and still has good connections there for work that I don't want to do.

30 years ago, I used to take an M117 timing chain, cut it in half and put the two pieces side by side and make a 4 row belt the Harley rideres were jealous of. I tried it again with my last chain and found that if I did that the belt would be too small. So it will have to be either a ladies double row belt, Or I will have to wait untill I do another timing chain job. The M117 engine must have gotten smaller over the years.

John Roncallo

Is it typical to replace the chain or replace the upper guides, cam oilers, tensioner, etc? I had all those things replaced, but the chain itself was not replaced......chain hadn't stretched.
Thoughts? 87 560SL 97,500 miles.

In my opinion, the only reason to replace the chain would be to eliminate stretch. In my car, even with 3000 mile oil changes and no abusive driving (I was told) there was 4 to 5 degrees stretch. It was recommended to me to replace it while I was in there. So I did. If you have no stretch after guide replacement, I think you are OK.

97,500 is about the right milage. How do you know it's not stretched. A chain only is the easy part. A good MB tech could replace that cain in under an hour, of course they will charge you 8.

John Roncallo

Now you got me all concerned. My 500sel has 215k miles with original chain. The only noise I hear is from a lifter. It comes from the right bank and I think the camshaft is worn. I haven't checked it out yet because engine is running fine (except the slight ticking noise). It actually has gotten more intense so it got my attention. I have a set of 4.5l camshafts from a 1973 sl. Do they fit?