Broken chain rail.

 

Wear marks from a loose chain on the head.

 

Very important rail to change is #11. Wear on this rail along with a stretched timing chain are the two biggest reasons for the head wear. This rail is often neglected and can be easily removed without removal of the timing cover. The pin is located under a plug which has to be removed to gain access to it. To pull the pin thread a tap into it until it binds and rotates than pull on the tap.

 

Worn and broken guides..........

 

Bad versus good tensioner............

 

Kiss of death............what happens when a chain fails..............

 

What a new slider / rail looks like....

 

A new timing chain for those square cam gears................

 

180 views and no comment on this.

Wow.

Where am I??

SL107.com?

 

Chain rail pin removal tool

Home made W107 chain quide rail pin removal tool. I have found this set very helpful.

 

I was waiting for a picture of the square sprocket.
I also have seen them used on the muffler bearing drive gear.

 

Here's a newbie question: It looks like you can change some of the guides with only the valves cover off. True? I'm thinking my covers are leaking and will need to change the gasket, so....

Also, great pics...

 

Here's a newbie question: It looks like you can change some of the guides with only the valves cover off.

The important ones, yes.

 

Very nice of you to put this together for the board, Nobby!

 

The early 107 SLs have metal backed guides. It is generally accepted that these should be retained if at all possible, rather than install the newer all-plastic guides.

Apparently aftermarket metal backed guides are available in Germany for the M116 engines, but not for the M117.
http://www.benzworld.org/forums/att...e-sec-sel-sd/341675d1289487261-re-enforced-timing-chain-guide-now-guiderail.pdf

There is another thread that indicates heavy duty plastic and metal backed guides are available for later cars. This is a link to that thread.

This pic shows a metal backed guide as well as the chainmarks on my car.

 

Good addition, WWW.

The M110 still uses metal backed guides.

 

!973 tensioner. Still looking for my worn '73 tensioner guide.

 

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Added 12/4/2010

 

The M110 engine timing chain.

http://handbook.w116.org/Engine\110\05-320.pdf

 

Interesting... The cams counter-rotate...

Strange that MB would choose that. Doesn't seem logical, especially as it results in so few engagement of teeth on the left cam gear.

Oh well... Those krauts seem to know what they are doing elsewise, so who am I to question?

Thanks for posting...

 

Another sloppy chain..........

 

M110 chain tensioner break down..........

 

These are the upper guide rails and tension out of my '73. They are metal backed.
It is my opinion (and I think the pics. substantiate it) that the damage was caused by a failed tensioner. Note the left side rails show almost no wear.

 

If the tensioner failed, why was its guide so worn?

 

Nobby, the m110 tensioner you showed was an early version, the newer ones don,t have the small spring and check balls.

 

I'm sorry I didn't keep my old one and break it down.

I was just happy to be rid of it.

Did you take one apart?

 

Yes, you pretty much have to take it apart in order to "reload" it if your going to reuse it. The spring and oil pressure push the piston out, when you relieve the pressure the piston pops out more and you can't push it back in all the way because the check ring stops it. You have to pust the piston out and reinsert it. When I did the head I wasn't going use the old one so I played around with it.

 

Ya, I knew about the reloading if re-using. But I just replaced and used the old one as a basketball.

BTW, mine was fully deployed upon removal.

 

Chain was slapping against the rail and the head.
The tensioner does have a spring that keeps some tension but if the hydraulic pressure is lost it is relying on only the spring.

 

Were those rails JUST metal or were they lined with rubber?

 

They have a hard lining of some composite. Don't know what it is.

 

I've seen a lot of chain drives, from airlocks to bucket elevators, grain combines to motorcycles, drum dryers to apron feeders. One thing that is remarkable, especially in high-velocity chains, is the slack will set up a standing wave, and will hold that curvature, as long as the velocity is constant. Of course, for our engines, the velocity is far from constant, so the chain suffers "impulses" from the crankshaft as the throttle and engine load changes. I think the tensioner should only serve as a guide to the standing wave, and help when the velocity changes cause impulses or fluctuations in this standing wave.

I recall an old grain combine we had, that used a chain drive that was visible on the outside of the machine. The "tensioner" was a block of oak wood, that only contacted the chain when the unit was slowing down or starting up, otherwise, the standing wave obtained in the slack of the chain, curved away from the block of wood when operating at speed. I have seen similar phenomena in other chain drives as well...

Kinda cool.

At first blush, Rowdie, I would have thought your tensioner had "locked up" in a fully extended position, riding too aggressively against the chain. I can imagine a situation like this where the standing wave would then be influenced to move to an area of slack, ie the other side of the cam gear, thereby riding more aggressively on that guide as well. No wonder the left side is illustrating less wear... the guides are in align with the chain, and far removed from the influence of the tensioner and chain standing wave...

Of course, I may be in a mescaline haze about now???

 

Of course, I may be in a mescaline haze about now???

If you are......we need to talk!

 

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Upgraded Timing Chain Guide