560SL Timing Chain Question - PeachParts Mercedes-Benz Forum

regsatx · #1 02-02-2007, 07:03 PM

How can you tell if a 560's timing chain has been replaced if no records are available? Any way of checking? Car has 142k miles.

Thanks

KCM · #2 02-02-2007, 07:57 PM

Take a valve cover off. Mark the chain with a marker or paint. Slowly rotate the engine a little at a time using a large socket on the front pulley bolt. Rotate the engine clockwise from the front so you don't loosen the bolt. Check to see if you can see a removeable connector link that connects the two ends of the chain. This will consist of a link with two pins attached, a side plate, and a thin spring-like retainer. Keep rotating the engine and looking until the paint mark comes around. If you can't find the link, than most likely the chain has never been replaced. To my knowledge, no endless chain is available, and if it was, the whole front timing cover would need to be removed to use it, which is very unlikely would happen. If you find a link, the chain has been replaced. It is also very unlikely the chain would have been replaced more than once with those miles.

Strife · #3 02-02-2007, 08:22 PM

It's also possible (but unlikely) that the link was peened or pressed - that is, the ends were mushroomed into holding the plate. But this should also look different than the other links.

I've also noticed that the LH valve cover can get scored with a loose (lots of miles) timing chain - if the scoring looks fresh, it probably hasn't been changed - or someone has been using the "torque the valve cover bolts to 50nm" method of stopping valve cover gasket leaks

. If there is none or the scoring looks old, it probably has.

Chas H · #4 02-02-2007, 09:20 PM

It's been a while since I replaced a t/chain. It did not come with a retainer type master link. Nor did the 3 or 4 before it. The master link required peening to secure it. That said, the peening operation applied by me was visibly different from the manufacturers.

deanyel · #5 02-02-2007, 10:24 PM

Whether it's been replaced is less important that what condition it's in at present. Double row chains are pretty much bulletproof but you should have the guides/rails and tensioner checked out if you don't know the history of the car.

regsatx · #6 02-02-2007, 11:19 PM

starts up smooth and is obviously well taken care of. Dealer service records end at about 117k and nothing about and chain replacement. Should I worry or just enjoy the car? In doing a search I hear they sometimes clang at cold start if chain is going south. Thanks for all the replies!

Thanks

Roncallo · #7 02-03-2007, 07:44 AM

If it doesnt rap on startup the first thing in the morning, then I wouldent worry about the chain. But the guide rails are another problem.

John Roncallo

JPMOSE · #8 02-03-2007, 07:50 AM

When I start my car up from a cold start I hear noise for about 1 - 1 1/2 seconds and then it disappears. I assumed it was lifter noise until the oil pumps up. Should I be listening for something else?

Roncallo · #9 02-03-2007, 08:02 AM

You should hear niether. A lifter noise will be a little higher piched and lower in volume. When you have been arround MB's enough you get to know the differnce. Also usually lifter noises take a long time to go away after startup if they ever go away. 1 or 2 seconds sounds much more like a chain.

Another way to tell a stretched chain is by how far the cam timing reference marks are off by with the engine at #1 TDC. This should only be done by rotating the engine to TDC in the direction of engine rotation only. If you over shoot TDC, then rotate the engine backward enough to get the cams to rotate backward slightly and aproach TDC in the direction of engine rotation agian without overshooting. Please note that as you apprach TDC the engine wants to overshoot as the crank goes overcenter, so you have to go slow allowing compression to relieve etc.

John Roncallo

JPMOSE · #10 02-03-2007, 09:48 AM

Thanks for the quick reply John. I didn't think it was normal either. My S320 never made a sound upon starting (nor does my 250SL). My most experience has been with a 300SD....well you know the noise she would make!

So I'm at 92k on my 1987 560SL. Last summer I had the valve stem seals replaced. One of the chain guides was cracked in half (I was very lucky that it didn't get loose and cause problems!) and replaced. My mechanic stated that while problems exist for the 420 engine, the 560 was more bullet proof. He also stated there was some chain stretch but not any thing to worry about. Despite his comment, I was planning on replacing the chain and components at 100k. Maybe I should do it now? What all should I have replaced besides the chain? I plan on keeping this car for the long haul and don't want to spare any expense. Let me know what you think. Thanks!

Strife · #11 02-03-2007, 10:37 AM

While the top of the engine is apart and all the accessories are off, I did the following on my two SL's, one at 84K and one at 95K:
1. Timing chain
2. Valve cover gaskets
3. Oil tube fittings (cheap, but crucial)
4. Tensioner
5. Upper guides and tensioner arm plastic or assembly of arm+plastic
6. All front belts
7. All front hoses

Keep in mind that water pumps are known to fail at 100K, and doing the timing chain job gets you 3/4 of the way there (and if having a shop doing the work, you should get a big labor break)

This is also a great time to do a major engine compartment cleaning.

JPMOSE · #12 02-03-2007, 10:49 AM

Tell me about the oil tubes? I did replace all the hoses and belts. Water pump would be a good idea too.

Strife · #13 02-03-2007, 01:52 PM

There are oil tubes that run along the top of the cam bearing towers on each engine head. They get old and clog or shrink and pop out. When this happens, little or no oil gets to the cams/bearings/followers, and this is very bad and has expensive outcomes. The oil tube fittings themselves are maybe $10 and are very easy to replace - but it is CRUCIAL that the fittings, which are barbed are pounded back in with a rubber mallet so that the tubes are entirely seated in the little v-pillows along the towers.

I bought my 85 380SL with a cam oiler tube that literally lifted off of the towers. The cam lobes were scored, and many of the cam followers were flat. Even with my own labor and very careful shopping of aftermarket/eBay parts, this cost almost $400 to repair. All for the lack of $10 of parts and a little preventative maintenance.

JPMOSE · #14 02-16-2007, 09:19 PM

Well today was the big day! I had my chain, tensioners, guides and oil tubes replaced today on my 560SL. Now at 92K, the upper plastic guide was cracked in half....last July when I had my valve stem seals replaced, the upper guide was replaced on the other side (84,000 miles at that point).

LET THIS BE A WARNING! Here is a car that has always been garaged, driven mainly on highway but gently. Always had Mobile 1 synthetic oil. Yet, the chain has about an 8 degree stretch and both upper guides were broken. I was extremely lucky because both guides were cracked in half but didn't separate and cause major damage. Most experts recommend 100K intervals for the 420 and 560 engines. My case may be the exception...not the norm. But it does go to show you that there is a slight risk your engine could have early problems as well. Pulling your valve covers and doing an inspection may not hurt!