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Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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22,199 Posts
Mark the chain and the old sprocket.

Remove the sprocket.

Compare old sprocket to the new sprocket, and mark the new sprocket in the same location with regards to the woodruff key slot location.

Install the new sprocket assuring the marks on the new sprocket and the chain line up.


Disclaimer:
I have never replaced a cam sprocket. So I don't really know. My biggest worry would not be getting the cam sprocket back in place, but worrying about the chain slipping a tooth on a lower sprocket. Always crank the engine by hand to measure all timing marks before starting the car when you are done the job.




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Registered
1974 450sl, 1986 190e, 97 sl320 40th sold
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506 Posts
LOL thanks man.... nothing like drunken advice. I thought about marking the chain and gear but you have no reference on the new gear. Well actually i guess you could lay one gear on top of the other and line up the slot where the key way goes and transfer the mark. Im sure ill make sense of it when i start tearing into it !
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
Joined
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5,255 Posts
Mark the chain and the old sprocket.

Remove the sprocket.

Compare old sprocket to the new sprocket, and mark the new sprocket in the same location with regards to the woodruff key slot location.

Install the new sprocket assuring the marks on the new sprocket and the chain line up.


Disclaimer:
I have never replaced a cam sprocket. So I don't really know. My biggest worry would not be getting the cam sprocket back in place, but worrying about the chain slipping a tooth on a lower sprocket. Always crank the engine by hand to measure all timing marks before starting the car when you are done the job.




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Fonzi, you must be really good sober! good advice.
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,255 Posts
Hey Yamaha, if you do happen to end up a tooth off it's not hard to correct. DON'T let the chain drop while removing the sprockets. Just do one at a time.
 

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Registered
'71 250, '78 450SLC 5.0, '78 450SL, '81 380SLC 5.6, '89 260E, '15 Kia Sorento
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5,269 Posts
Ok gonna be tackling this job this weekend and i have a stupid question. I'm going to be replacing the cam gears and from what ive read you can get enough slack in the chain with the tensioner removed. Heres the question once i pull the chain up off and slide out the old gear how can you be certain you have placed the new one in the same location ? it seems with that amount of slack it would be easy enough to accidently be off a tooth one way or the other ? thanks

Great thread btw nobby ! thanks
I'm my case, if the sprocket was off by a tooth the guide slot on the cam wouldn't line up with the channel in the sprocket.
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,255 Posts
Cam marks line up

I'm my case, if the sprocket was off by a tooth the guide slot on the cam wouldn't line up with the channel in the sprocket.
That's right dgosh, that's why I needed to adjust mine by a tooth but I did it without taking the sprockets off again. The idea is to line up the marks before mounting the sprockets but after putting on the tensioner I found it was out by a tooth on each sprocket.
 

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Premium Member
2004 CLK 240 Coupe
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11,370 Posts
I've been wondering for some time....and anyone who has done this job is bound to know...

Where does the timing chain lubrication come from?
 

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Registered
560SL,380SL
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4,012 Posts
I've been wondering for some time....and anyone who has done this job is bound to know...

Where does the timing chain lubrication come from?
This is a good question - but I suspect that there is a lot of oil being thrown around the inside of the front cover during operation, and this incidentally gets to it - and then this is carried around the path of the chain. The oil pump is actually bolted to the timing cover, which seems odd - but it obviously works. The pump oil gets routed to the filter, and then back to the cover to oil the intermediate gear and distributor gear bushings, for example.
 

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Registered
1991 300SL-24; 1978 350SL
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22 Posts
jerking my chain

I'm just getting started on my first timing chain / guide / tensioner project and could really use some help.
Mine's a 1978 350SL - a Euro. I've checked the timing and the right cam sprocket is off by about 13 crankshaft-degrees but the left sprocket looks to be right on the mark. There's no indication of any slapping at the cylinder head or in the valve cover. There's about 1/2 inch of 'play' between the chain and the inner right guide. Does all of this make sense? Do I have just a stretched chain or something more ominous?

Once I get this rolling, should the chain be changed before the guides or the other way round?

Thanks for the help.
 

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Premium Member
1987 560SL
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2,338 Posts
Hey, this nobby thread is a classic and you woke it up. Always replace the guides even if they look good. Heat, age, material and design make them unreliable. Check your chain stretch by trying to move a link while it resides on a top cam sprocket, it should not move. The play you refer to is likely because the tensioner is relaxed with no oil pressure. Makes no sense to do this in separate operations, replace upper guides, chain, oilers, sprockets, tensioner and maybe gaskets since while you are in there. Here is my parts list:
 

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Registered
1987 560SL (L.Tonk) [92,700 miles]
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273 Posts
First off, a huge thanks to everyone for sharing their knowledge, wisdom, and experiences. I only found out about the guide rail failure mode recently, so I'm getting ready to do this work to my 87 560SL as soon as I can.

I tried enumerating all the parts in PanzerPuff's video (clockwise from upper left).
I marked the unknowns in red -- hopefully, someone can help out.

* for-sale sign (optional)
* reversible cable ties
* pin puller
* power steering filter
* pin (not sure which pin this is)
* tensioner rail
* tensioner rail lining :)thumbsup: Rowdie)
* O-rings?
* upper guides (2)
* lower guides (2) (in the centre: :thumbsup: Rowdie!)
* tensioner (w/ gasket)
* valve cover gaskets
* fluids (distilled water, antifreeze, ATF What's in the aerosols?
* master links :)thumbsup: Aussiemerc: two, because you always lose one!)
* big box of spare circlips
* timing chain
* oilers
* belts
* sparkplugs
* sprockets
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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31,983 Posts
The pin looks like a guide pin.
You don't need to buy the entire tensioner rail unless the lining is worn through. You can just buy the lining.
The black guide and the one above it are lower guides.
 

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Premium Member
1987 560SL
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2,338 Posts
First off, a huge thanks to everyone for sharing their knowledge, wisdom, and experiences. I only found out about the guide rail failure mode recently, so I'm getting ready to do this work to my 87 560SL as soon as I can.
I tried enumerating all the parts in PanzerPuff's video (clockwise from upper left).
I marked the unknowns in red -- hopefully, someone can help out.

* for-sale sign (optional)
* reversible cable ties
* pin puller
* power steering filter
* pin (not sure which pin this is)
* tensioner rail
* tensioner rail lining :)thumbsup: Rowdie)
* O-rings?
* upper guides (2)
* lower guides (2) (in the centre: :thumbsup: Rowdie!)
* tensioner (w/ gasket)
* valve cover gaskets
* fluids (distilled water, antifreeze, ATF What's in the aerosols?
* master links :)thumbsup: Aussiemerc: two, because you always lose one!)
* big box of spare circlips
* timing chain
* oilers
* belts
* sparkplugs
* sprockets
Man you are thorough. In red:
PIN = Not needed as the pins you pull with the pin puller get reinstalled, they do not wear out. Maybe you would need one in case the old gets stripped or damaged, but that would be rare using the pin puller designed for this purpose.
O-rings? = I still have them not installed. They came with a rail kit that included the bottom rails so they ended up in the opening shot.
Aerosols? = That is PB blaster or better yet spray Kroil for any tight threads. Also shown is WD-40, same idea, and finally brake parts cleaner that I spray on anything that looks dirty before reinstallation. If you have a parts cleaner that would be much better.
Yes two links because as Aussiemerc says they get dropped, but they are so cheap and you use one to pull the new with the old, and the general caveat is never to use a master link twice, perhaps because those tiny circlips can get weak with reuse, but then again I have reused master links on my motorcycle chains with no issues. It is a peace of mind kind of thing as it is so tedious to get to that link.

Good luck with this and keep us informed of your progress.
 

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Registered
1987 560SL (L.Tonk) [92,700 miles]
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273 Posts
Thanks PanzerPuff -- your video was hugely helpful.

Tonk is going to the barn in about a week, so I'll have to wait until spring to get started.

I can't edit my original post anymore, but I'll leave off with the EPC diagram of the Timing system.
 

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