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1972 350SL
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Discussion Starter #1 (Edited)

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1972 350SL
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441 Posts
Discussion Starter #2
After adjustment (rotation) of left cam

We have the issue with the crank and left cam(drivers) cam and crank having to much slack with all three alignment marks in position.

Also noticed that with all marks in position where is slack between the left and right hand cams, where the "valley" sprocket sits, you just simply cant get the chain over the link to take up the slack.

we were fiddling around trying to solve both issues, and what we found was able to rectify all the slack, was to move the left(drivers) cam back(counterclockwise as you face it) a few degrees as shown in the pic.

both crank, and right(passenger) alignment marks remain unchanged. is this a symptom of sprocket wear? they dont look worn, or is an offset woodruff key required?

Or is there a trick about moving some marks slightly out of alignment, and when the chain is on and engine rotated everything comes into alignment? iv seen that on the quad cam subaru motors. Or should it be a simple line everything up, install chain and go?

Thanks.



Thanks for any
 

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1974 450SL; 2009 CLS550
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202 Posts
Your fine, these vehicles have a hydraulic tensioner which will adjust the tension on the passenger side before the cam. There is no foreseeable problem. You want slack, check out some of the Le Mans cars when the timing chain is swapped. It is ridiculous.
 

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Timeship, see you yesterday, but you already knew that.
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Too much depth in the vally's on the cam sprockets is what it looks like from the one picture.

Can you get more pictures without the chain on the sprokets?
 

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Timeship, see you yesterday, but you already knew that.
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you would like a pic of the cam/crank sprockets without the chain on them?
No chain, and all the way around the sprockets without moving them from their assembly position(s).
 

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Timeship, see you yesterday, but you already knew that.
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When you're looking at a sprocket guys heres how you tell it is worn.

The smaller the green area's at the tip of the sprocket, the more worn it is.

Now you take one pocket that is, lets say, 1mm worn and times it by about eights pockets the chain is always in.

That makes almost 10mm of chain slack on the non tensioner side. With the tensioner fully extended.

Which makes a DOHC, rattle, ping (spark knock) and diesel, even with that brand new chain.

Have a look at the picture.
 

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Timeship, see you yesterday, but you already knew that.
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Yes, you need sprockets.
 

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Timeship, see you yesterday, but you already knew that.
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Thank you!
Np, sometimes its the experianced eye that see's whats wrong with a picture.


Hopefully the picture explains what the issue is for you.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Guess I missed this. I thought you had new sprockets. I agree they are a good investment since you have gone this far. Most expensive will be the dist drive IIRC.
 

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1972 350SL
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Discussion Starter #13
It sure is! Over $400. It has noticeably less wear and the helical looks pretty good as well. I think I'll live with it. Must draw the line somewhere.

If anyone disagrees - shout now.

Guess I missed this. I thought you had new sprockets. I agree they are a good investment since you have gone this far. Most expensive will be the dist drive IIRC.
 

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It sure is! Over $400. It has noticeably less wear and the helical looks pretty good as well. I think I'll live with it. Must draw the line somewhere.

If anyone disagrees - shout now.
I think we all agree. lol.


After you put it back together, you will see, everything will be perfectly lined up.

BTW you should be soaking the chain right now, while you wait on the gears.


A coffee can with oil enough to cover the whole chain should do it.
 

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1972 350SL
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Discussion Starter #15
I think we all agree. lol.

After you put it back together, you will see, everything will be perfectly lined up.

BTW you should be soaking the chain right now, while you wait on the gears.

A coffee can with oil enough to cover the whole chain should do it.
Thank you. Will do. What you say makes perfect sense. While the wear at any one point does not look real bad, the cumulative effect would account for the slack.
 

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Timeship, see you yesterday, but you already knew that.
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Thank you. Will do. What you say makes perfect sense. While the wear at any one point does not look real bad, the cumulative effect would account for the slack.
Yes sir.

I cant wait to hear it run again, it will be like a head trip back to '72.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Wow :eek: The price has gone up.
Coffee can with oil is also good for pumping up the new tensioner before installing.
 

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Timeship, see you yesterday, but you already knew that.
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Wow :eek: The price has gone up.
Coffee can with oil is also good for pumping up the new tensioner before installing.
Totally. Now if we could compile all these good tips into one topic. lol.
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,259 Posts
Worn sprockets

When you're looking at a sprocket guys heres how you tell it is worn.

The smaller the green area's at the tip of the sprocket, the more worn it is.

Now you take one pocket that is, lets say, 1mm worn and times it by about eights pockets the chain is always in.

That makes almost 10mm of chain slack on the non tensioner side. With the tensioner fully extended.

Which makes a DOHC, rattle, ping (spark knock) and diesel, even with that brand new chain.

Have a look at the picture.

Very informative- thank you
 

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Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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22,217 Posts
I wondered why it is recommended to replace cam sprockets when replacing the chain thinking:
1) if i am replacing the chain due to stretch, do i really need to to the sprockets?
2) if there is more force on the cranks sprocket, and each tooth has had twice the wear of each cam sprocket tooth, wouldn't it make more sense to changed that one first?

I realize that the reasoning behind #2, not changing the crank sprocket, is that it is alot of work, and the cam sprockets are not. However, now, after reading this thread, I realize that a major reason for changing the cam sprockets is the fact that they essentially get smaller over time, decreasing the overall chain path, effectively making the chain slack. So not only should you change any sprocket when convenient, but also since the cam sprockets are larger, their wear might have a greater overall effect on chain slack when they wear... or the chain travels along a larger degree radius on the cam sprockets too.

Well if my logic is not sound, whatever the case, this thread convinced me to DEFINITELY, change my cam sprockets when i replace my chain.

Thanks!


I recommend this thread for egv107.
 
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