OM606 tensioner refurb? - PeachParts Mercedes-Benz Forum

DieselJim · #1 09-24-2015, 10:24 PM

Got my parts from the dealer for some weekend wrenching. The brass shims are very thin. I'm sure unless well done it wouldn't last near as long as OEM but has anyone re-shimmed their tensioner. Don't see any reason why this wouldn't be easy if you had some brass alloy of appropriate thickness? This is more of a curiosity and I might reshim the old one I'm taking out for a spare

Jeremy5848 · #2 09-24-2015, 10:29 PM

Pictures would help.

DieselJim · #3 09-24-2015, 10:39 PM

So that is a good idea. will take some before I put in the new part and will take some of the old part and upload them. The sacrifice is very thin. Guess you want to keep that tensioner shock absorber in really good shape and minimize belt vibrations

DieselJim · #4 09-24-2015, 11:01 PM

Several websites that sell shim stock. Just need to figure out a target thickness and hardness

Jeremy5848 · #5 09-24-2015, 11:25 PM

The shim notion puzzles me (why I asked for pictures). AFAIK neither of my OM606 belt tensioners are shimmed. Can you explain where the shims go? EPC does not show shims.

DieselJim · #6 09-25-2015, 05:23 AM

Sure. So I have the tensioner lever new from MB. Its a pretty cast part. Very light. In the hole where the tensioner pin goes their is a thin piece of brass in the hole on each end that the PIN goes through. A small gap is in the middle. The pin pivots on the shim between the spring and shock, not touching the cast metal. Another interesting bit the metal appears to be cast aluminum.

I think I expected a significant almost bushing size piece of brass instead of a thin shim. If you do a google image search you find lots of pictures.
The following one illustrates it fairly well. Looks like it might be a knock off but you can see the shim and where the shim stops in the middle of the part. http://img2.en.china.cn/0/2_895_31426_499_297.jpg

benedict · #7 09-25-2015, 10:30 PM

DieselJim,

I just opened a fresh (from the dealer) part so as to see what you are talking about. I can see why Jeremy is confused as I was.

These are not shims but are in fact called a flanged sleeve bearing (split type) with a PTFE coating to sleeve the bearing. The bearing is usually made out of low carbon steel or sintered bronze. The PTFE coating has a low friction co-efficient if not spun at high speed, extreme heat and cold resistance (-190C to +260C), corrosion resistant and many more pro's.

You might also hear them referred to as oilless bearings or self lubricating.

So, you can replace them. You just need to measure the thickness, length etc and scratch away the PTFE coating to see what is behind i.e bronze. Sorry, I don't want to do a test with my brand new one

The PTFE coating is .02mm thick, carbon steel .5mm to 2.7mm and sintered bronze .2mm to .35mm

I took a few photos and an image of a flanged sleeve bearing, split type.

DieselJim · #8 09-25-2015, 11:40 PM

Quote:

Originally Posted by benedict

DieselJim,

I just opened a fresh (from the dealer) part so as to see what you are talking about. I can see why Jeremy is confused as I was.

These are not shims but are in fact called flange bearings with a PTFE coating to sleeve the bearing. The Bearing is usually made out of low carbon steel or sintered bronze. The PTFE coating has a low friction co-efficient if not spun at high speed, extreme heat and cold resistance (-190C - +260C), corrosion resistant and many more pro's.

The PTFE coating is .02mm thick, carbon steel .5mm to 2.7mm and sintered bronze .2mm to .35mm.

You might also hear them referred to as oilless bearings.

So, you can replace them. You just need to measure the thickness and scratch away the PTFE coating to see what is behind. Sorry, I don't want to do test with my brand new one

I took a few photos and an image of a sleeved bearing.

lol so they are strong sleeves, shims but they are very high quality. Brass wouldn't last long. Probably why the aftermarkets fail so quickly, a cheap sleeve! Thanks for enlightening me on the technical jargon. That was kind of the point of this post. However one resleeved with a decent quality piece of metal might last for a few days in a pinch

benedict · #9 09-26-2015, 12:11 AM

I've never seen the aftermarket ones but I did hear of them failing so I invested in the genuine article. Are they really just sleeved with brass?

qpooqpoo · #10 09-26-2015, 12:14 AM

QUESTION!

Guys, why do you need to change the tensioner for this car? That 606 tensioner looks like its simply a solid metal piece. What could honestly go wrong? What are the symptoms?

I ask because I have a 606turbo w210 my belt drive has begun to squeak right on the ac compressor pully and the ac compressor and pulley are both new and the belt is very tight and new so I am thinking...can it be tensioner related? and if so how??

engatwork · #11 09-26-2015, 07:44 AM

The flanged sleeve bearing wears causing the tensioner to "pivot" around the pin. This causes misalignment on the belt, making it run to the front. The more wear on the bearing, the more the belt rides off of the tensioner pulley. I think it wears pretty slow so once you see the belt start riding off of the correct pulley position you have some time before it will actually leave you sitting by the road.

Jeremy5848 · #12 09-26-2015, 11:23 AM

Absolutely correct. Over time this can fail the entire tensioner "system" and put excess wear on the other items driven by the serpentine belt.

Thanks for the pictures and translation. I've never tried replacing the flange; I suppose it would be possible but if it is really worn then the pivot pin will also be suspect. One can always imagine a person located in a remote area where parts are unavailable; in that case given time and shim stock one could fabricate and rebuild. For most of us, however, replacement of the pin and "lever" is the best solution.

It's critical, BTW, to make sure the parts kit includes the seal at the rear of the pivot hole and the cap on the front of the lever arm. These two items keep (try to keep?) water and dirt out of the "bearing." Dirt turns the bearing into a grinding machine, which is what wears out the flange and pivot pin.

In EPC the seal is #29 (it's white plastic, doesn't really look like a seal) and the cap is #47 (black plastic).

This applies to all MB engines with this type of belt tensioner.

Jeremy