560SEL busted Timing chain rails (help needed) - PeachParts Mercedes-Benz Forum

Eain Murphy · #1 03-27-2007, 11:06 AM

Morning, I hope this finds you all well.
I recently purchased a 1987 560SEL off of ebay with what the previous owner said was a busted timing chain. I got it cheap ($400) since the car had 200K+ miles on it and the body is in great shape so I took a stab at it. I also purchased a set of heads for it on Ebay (that damn ebay is like elecronic crack -- I'm addicted). Upon getting the car the owner said he heard some slapping noise upon start up and shut the engine down. He took it to a mechanic who said that the timing chain broke. Also it cracked the drivers side valve cover. That to me meant that the chain jumped probably due to the guide rails. SUre enough, I get it home and pull the valve covers. The chain is intact. however both guide rails on the driver's side have cracked off. They were laying down in the engine and I retrieved them. They actually didn't look that bad for going between the sproket and the chain.
No this is where it gets weird. My timing mark on the passenger's side looks good but the driver's side is clearly off by a tooth. The chain has a lot of play in it so I tried to just hand crank the chain around to see where it hits. I painted the top link on the driver's side cam and I can rotate the chain all the way through and back to the orignal cam? Slightly tight in a spot or two but just reversing the rotation and then progressing forward caused it to go right through. So I figured that I must have my valves bent out of the way so that the piston is not hitting them. So I cranked the engine by hand so that each cylinder should have it's valves closed and did a pressure check on them using my compresser and all held pressure??? Could it be that the heads are OK? Am I not thinking of something?
(BTW, I should mention that my daily driver is a 1948 dodge which has a flat head side valve engine. Very simple design. This overhead cam high tech german engeneering stuff may be throwing me if I am not thinking about correctly.)
The final question is that I purchased a new timing chain and rails as well as a tensioner. Can I change the timing chain guide rails without pulling the heads (If they don't need to be pulled)? I plan to purchase this week the access to the pindelski.com website to help me out on the specifics. I am just trying now to figure out what the big project will take.
Thanks in advance to any input that you may offer.

Strife · #2 03-27-2007, 12:20 PM

It IS possible, theoretically, to get lucky; but the valves may still be bent a little, they may stick, and at the very least the valve guide wear may be greatly accellerated. Someone with more experience will have to advise you if it's worth the risk. It would be really bad to have a valve stick at speed.

Yes you can do the timing chain/guide work without removing the heads, but you will need the right kind of valve spring compressor and pin puller to do the job. It's possible to make your own tools or modify existing ones if you are handy.

ctaylor738 · #3 03-27-2007, 12:46 PM

Who knows? Your compressor test is promising. You can put the chain back on the left side in the correct position and run a compression check to be sure.

There is nothing that you're not getting about the valves and their timing. It's the same principles as your Dodge.

nhdoc · #4 03-27-2007, 01:33 PM

Isn't it also possible that his chain is just stretched to the point that the left cam could just be showing that and it hasn't "jumped" a tooth at all? I mean the amount of chain between the crank and the right cam is relativley short, then there is a long section of chain between the two cams where it travels back into the "valley" in the middle. It would be unusual that for a well worn chain you'd get the same timing reading on both cams so maybe he lucked out and the guides just broke off and didn't cause the chain to jump. I think if it was me I'd first roll in a new chain and install new guides without altering the timing at all since he said he can turn the engine through an entire revolution. Then I would check the timing marks again and see where everything was. With a new chain you should be pretty much at TDC with both of the marks lining up on both cams. Then if one was off you'd know for sure it had skipped a tooth.

Just thinking out loud...I'm sure others more knowledgable will tell me I'm wrong.

ctaylor738 · #5 03-27-2007, 01:42 PM

Good idea. And it's not much extra work to roll the new chain in first. To get an accurate reading, you need to pull the chain tight from the left sprocket to the right, like the tensioner would hold it.

I am also thinking that you see bent valves on 380's and 420's. Offhand, I don't recall a 560 with this damage. Maybe the 560 has some more room in the combustion chamber.

david s poole · #6 03-27-2007, 05:53 PM

sounds to me like you lucked out.change the chain and tensioner and those 3 guides and then see what you have.it doesn't sound like the valves have been hit at all or you couldn't keep pressure in the combustion chambers.

Alkraut · #7 03-29-2007, 07:00 PM

Take a look at the guide rail pieces that you fished out. See if you can identify the one that was originally on the upper inside. That would be the one that "rode" through the sprocket, if it did at all. There may be long wear marks, but look for sprocket marks. Just a shot. If you don't see any, your problem may be a real stretched chain that started slapping worse when it broke the guide rails.

In any case, I agree with the above recommendation of replacing the chain first, and see the situation. Good luck and let us know what you find!

Eain Murphy · #8 03-29-2007, 07:09 PM

I just got all the parts for the job and stripped down the front of the engine components (even pulled the water pump which I probably didn't have to do in retrospect). I will be fishing the new chain in. One more short question.
Is there a trick to getting the guides behind the new chain or should I try to get them past the old chain since it obvously stretched a good bit?
I will give you guys an update.
Cheers.
Eain

Alkraut · #9 03-29-2007, 08:18 PM

I am planning to do mine this Spring, so I don't have the experience yet, just read alot. My sugestion would be to replace the guide rails with the old chain still in place. Remove the chain tensioner on the right head to get even more slack. I believe the rail pins need to be pulled with a special puller, and the rails removed with a needlenose visegrip? One procedure I read recommended removing the left camshaft sprocket. I'm not sure if this is necessary to get the outside upper rail out, especially with enough slack. Once rails are done the new chain can be fed in and the tensioner replaced. Did you subscibe to the Pindelski website? If so, I would like your opinion, as I read that he has a good procedure for both rails and chain with excellent pictures. Thanks and good luck!

nhdoc · #10 03-29-2007, 09:35 PM

Usually you roll the chain in by attaching the new one to the end of the old one after cutting one of the links open on the old chain.

You can't replace the guides with the chain in the way - you'll need to remove the cam sprocket and pull the chain out of the way while you replace the guides (careful not to let it fall into the engine). I have a pretty good guide that is for sale from **************.com called "preventing catastrophic V8 engine failure" that details the whole procdure for replacement of both the chain and the guides. I recommend you get that booklet or another like it to help you through the job - there are lots of tips like how to get the pins out that hold the guides in place.