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1998 C280; 1987 560SL
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Discussion Starter #1
I have owned my 560sl now for about 4 months and today I finally got the opportunity to look at the timing chain and guides. I have put all of 10 miles on it since purchase and after today, I am glad - it was 10 risky miles. Of course, in light of the general condition of the interior of the car, my expectation was that the guides and chain had never been touched. The right side being the easier of the two valve covers to remove was my first look today. The two guides that I could see were dark brown. The tensioner guide is completely worn through and the chain is riding on the aluminum backing. The odometer is showing 154k, but since it was not functional, I would estimate 160 to 175. This is based on the PO's comments that it quit while he owned; it not long ago (4 years).

So preliminary plans are to renew the top guides and pull in a new chain. I will watch Panzer Puff's video once more before beginning dismantling the front components. Anyone have any recommendations on guide and chain kits? Glad I found this forum; this thing would not have had many more miles before self destruction.:eek
 

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Premium Member
1983 380 SL
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2,468 Posts
I just did my 380 this summer and I got the guides and tensioner from Autohausaz. They were fine. My chain and sprockets were like new (changed 20K miles earlier).

Don't forget the oilers... two sets.

You'll want to purchase a pin puller or make your own. While you're at it you may as well change the cam sprockets and don't forget new valve cover gaskets.

You'll need a 27mm socket to turn the crank with a long breaker bar, or better yet a long ratchet.

Good luck
 

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86 560SL
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1,243 Posts
I bought the guides from the local MB dealer, the cam oiler kits and the valve cover gaskets from FCPEuro.
I only had to replace the guides. The car had 47k miles on the odometer but was 30 years old and the chain, sprockets and tensioner all were still in good shape, however, the guides were dark brown and very brittle. Proof that age is just as damaging to the guides as mileage.
When removing the cam oilers more than likely you will break off some of the little plastic nipples that hold it in place. A simple speed-out bit, turning it by hand, works great getting the broken off plastic nipple out of its mounting hole.
 

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1998 C280; 1987 560SL
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469 Posts
Discussion Starter #4
Final assessment, 2 broken guides and the tensioner rail worn through. I was very lucky to be able to retrieve the pieces of carnage. Used a little grab tool I got at Harbor freight to pluck them out of the abyss.:thumbsup: Mileage shows 154K, but it was broke when I bought it. It is a miracle it survived for me to buy it. It wouldn't have gone much further. Chain stretch measures 12 degrees - next on the list.
 

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Premium Member
560SL 1986 244k miles astral grey / black
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401 Posts
You are extremely lucky!!

There is more then enough info on this forum how to replace them. I would recommend you to everything at the same time, guides, tensioner, sprockets, chain, oil kit and head gaskets. Took me about 2 days in total, as a first timer. Good luck!
 

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1985 500 SL in Signal Red, 145,000 miles, and rising whenever possible
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326 Posts
it took me about 4 weekends in spring 2017

but I was only throwing a few hours at it every time, and I did encounter some obstacles. Watch Ken's video again. and again. ( we have a secret plan to make him the king of you tube). Something will go wrong along the way.
1) don't panic
2) don't panic, watch the vid again, and search for whatever the problem is on here. One of us will have had it and beaten it.

welcome to the chain gang.:nerd
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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31,979 Posts
You are extremely lucky!!

There is more then enough info on this forum how to replace them. I would recommend you to everything at the same time, guides, tensioner, sprockets, chain, oil kit and head gaskets. Took me about 2 days in total, as a first timer. Good luck!
You did head gaskets too? All in two days? Amazing. :D Or did you mean cylinder head cover gaskets? (Valve Covers)
 

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1998 C280; 1987 560SL
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469 Posts
Discussion Starter #8
Elmer, I watched that video at least ten times, but the tensioner rail removal part is very quick and it is unclear on how he removed the pin. It appeared he used the same pin puller as for the other guides? This would not work on mine, as it has no internal threads and is bigger in diameter than the other pins. It is really a hollow brass bushing, rather than a pin - it is held in place with a plug.

I am doing all of this work at once - top guides, oilers, sprockets, chain, and tensioner. I am not doing head gaskets - no problem that I know of! I am not trying to set any speed records at getting this done. I am hoping to have time to pull the chain in Saturday. I am also helping my son build his house next door. This car is a toy - not a mandatory means of transportation.
 

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1985 500 SL in Signal Red, 145,000 miles, and rising whenever possible
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326 Posts
that's the chain tensioner pivot bush thingy

Elmer, I watched that video at least ten times, but the tensioner rail removal part is very quick and it is unclear on how he removed the pin. It appeared he used the same pin puller as for the other guides? This would not work on mine, as it has no internal threads and is bigger in diameter than the other pins. It is really a hollow brass bushing, rather than a pin - it is held in place with a plug."
you need a pair of long needle nose pliers. Insert them into the hollow sleeve, applying a little openeing force to them. They will pull the bush out. BEFORE you do that, grab a hold of the tensioner guide rail with a clamp or plier of some sort. Don't pull it up while wiggling the bush out, as you just make it harder to remove the bush. Once the bush is out, you can stick a long narrow bolt or screwdriver in there to stop your tensioner guide falling down. less than 8mm diameter will do the job.
 

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1998 C280; 1987 560SL
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Discussion Starter #11
Part of the problem is access due to water pump hose, but I will try my assortment of pliers. Thanks for the help.
 

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1998 C280; 1987 560SL
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Discussion Starter #12
I missed the tensioner rail the first time and the pin ended up getting stuck and could not pullout with the pliers trick. Ended up using a tap to tap the inside with a a couple of threads and then screwed in a bolt with a nut on it to pull it out. Liked to never got it threaded back in the tension rail!!!

So then last night I pulled in the new chain and, after completing, I noted the timing marks are way off! Do I need to install the tensioner and rotate by hand to take out any slack that may have developed?

Thanks.
 

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Premium Member
1983 380 SL
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I don't quite understand what you're asking. You installed the new chain and now the timing marks are way off? From the way you worded your question I'm uncertain as to when you replaced the tensioner, was it before or after the timing marks were way off?

I assume you rotated the engine clockwise the entire time and if so then slack should not be a problem. Even with the tensioner out. Reason: the number of links between the crank pulley and the cam pulleys (as long as the engine has only been rotated clockwise) sets the relationship in stone between all the pulleys. The tensioner will not affect that relationship (unless it's not there at all). However, if there is slack in the chain somewhere between the cam pulleys (not likely if you only rotated clockwise) then that can effect the relationship.

Double check the positioning of the chain by rotating the engine at least one full cycle with the tensioner installed. If you still see a discrepancy between the cam timing marks and the crank timing mark then you'll need to set the crank to 0 and then adjust the cams by altering the chain location on the cam pulley on link at a time in whatever direction is required to align the marks. Your point of reference is always the crank timing at 0 while #1 cylinder is at TDC. Make the cam marks be right when the crank is at 0. A few degrees difference is no big deal... you can compensate with offset Woodruff keys for any adjustments of less than 1 chain link.

Good luck. :thumbsup:
 

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1998 C280; 1987 560SL
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Discussion Starter #14
When I say way off, I am talking a few degrees. I rotated the damper to 0 and the valve timing marks were not right on like I was expecting. I doubt it is enough out to move the chain, but it may be more than an offset key.

I have put the tensioner on and will rotate a couple of revs and see what happens. I will measure how much each are out.

Thanks.
 

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1998 C280; 1987 560SL
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Discussion Starter #15
Okay, I was 10 degrees on the left - late and 25 degrees on the right - late. I moved the right sprocket up one link and now have 10 on the left and 5 on the right. Obviously I jumped a link when I pulled in the chain. I used velcro ties, and they did not fit tight enough. The old chain measured 12 degrees late on the right and was pretty close on the left (not sure I even measured it).

I did not change the sprockets. Could this be my problem - I know it has been recommended by most on the forum to change sprockets with the chain. They looked fine and I elected not to change them. So should I change the sprockets and then evaluate whether I need offset keys? As I understand, 10 degrees at the crank is only 5 at the camshaft, correct? So as it stands, I would need a 2 or 3 degree for the right and 5 for the left.

Thanks in advance for the help.
 

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1998 C280; 1987 560SL
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Discussion Starter #16
I would add that with or without the tensioner, I get the same readings. I have read several posts that measuring valve timing without the tensioner active gives incorrect readings. As Jyuma has stated below, as long as you turn clockwise, the chain should stay taught from crank through both cams and no difference in readings should occur. The slack should be under the right hand cam sprocket only.:thumbsup:
 

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1983 380 SL
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I'll add a proviso to my comments about the possible effects of the tensioner on chain slack. The tensioner has two components that effect slack, spring pressure and oil pressure. I believe the tensioner will take up most of the slack on spring tension alone. I don't know if there actually is a spring in the tensioner but when I change my tensioner it definitely tightened up the chain when I tightened the bolts holding the tensioner.

Now here's the proviso... if the tensioner is completely shot (or missing) it is possible for any valves under spring pressure to push the cam in one direction or the other. If the cam lobe is in a position where the valve spring pressure would be applying pressure to the cam opposite to the normal rotation nothing will happen, but if the cam lobe is in such a position that the valve spring pressure effect would be in the normal direction of rotation... and the tensioner is not taking up the slack... then the cam can and will snap forward under the pressure of the valve spring and that can change the valve timing until the slack is once again taken up. Watch Panzer Puff's video on changing the timing chain and you'll see it happening.

Bottom line... always set the chain timing with a good tensioner in place. :thumbsup:

Note: Worn cam sprockets can effect cam timing but unless they are very seriously worn, the effect will be minimal.
 

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1998 C280; 1987 560SL
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Discussion Starter #18
Yes that can happen, but it is easy to recognize it is happening. In fact that is how I jumped a link when I was pulling in the new chain. But you are correct it does not do so with the tensioner installed.
 

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Discussion Starter #20
So being an engineer, I have been trained that you must always know why. Everything we do is for a reason. I was having difficulty understanding why the valve sprockets needed to be changed, while the other internal sprockets were not changed. All I ever read was they needed to be changed because of the wear. So for $50 bucks I ordered new ones so that I could fully understand what the wear issues were. So they came yesterday and I had the opportunity to compare the old with new. It was quickly apparent that the key ways were significantly wider than the new ones. The shaft keys did not appear to worn.

Once the new sprockets and tensioner were reinstalled the valve timing was very close to on the money. So there is a reason to change the valve sprockets and it is due to key way wallowing. On my engine it amounted to severaldegrees of lag at each valve sprocket.:wink
 
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