Hi All,

I’m working on a ’64 190D which has a 220D motor in it of unknown (as yet) year. The timing chain broke (no bent valves) so I’ve put in a new chain as well as all new guides and sprockets as well as a new pre-chamber which I found was bad when I pulled the head.

My question is how does the 220D tensioner work? The manual from the 190D says the tensioner functions from oil pressure and you have to bleed it, but the 220D tensioner doesn’t appear to use oil as far as I can tell by looking at it. I realize now I should change the tensioner anyway, but is it just a spring in the tensioner or is there oil in there? It seams very slack right now, I can easily push the tensioner back in with my finger and it is not keeping the chain tight at all when I turn the motor over by hand. Needless to say I won’t try and start it until I get that chain tight, but any help would be appreciated.

Also I was wondering about the injection pump timing. There didn’t seem to be any marks for lining up the sprocket (and nothing in the 190 manual) and the old chain was completely off so I just put the new chain on lining up the crank and cam marks, but now I am wondering if I will have to pull the pump to get the timing right? If that’s the case can someone give me a quick description of how to do that? ie lining things up, I can remove the pump easy enough.

My last question is where on the block are the numbers stamped? When I looked up the new tensioner it wants to know “Engine Range: From 10-166609” so I’m wondering where I find those numbers?

Thanks for any and all help.

Regards,
Sven

The pic below is supposed to be a Timing Chain Tensioner from a 1968 220D.
The Red Arrow points to the Oil inlet hole.

The Oil for it comes from the Oil Gallery just like it does for the Main Bearings.
While Mercedes does not recommend turning any of the Engines opposite the direction of rotation on Engines that have the type of Tensioner you have it is calimed it is possible for it to jump a tooth if turned backwards.
Apparently the Oil Pressure is mainly responsiable for keeping tension on the Timing Chain Rail.

The Newer Models like mine have a slightly different set up that does not allow the Plunger to be pushed Backwards.

I do not know on your particular Engine but on the later model Engines the Engine Number is about in the Middle of the Engine Block on the Drivers Side (US models). It is right where the Head and the Block come together; not easy to see.

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84 300D, 82 Volvo 244Gl Diesel

Thank you. That is the correct tensioner. I will try priming it now that I know where the hole is and see if the tension improves.

What is the source of your Instructions that tells you it needs to be primed?

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84 300D, 82 Volvo 244Gl Diesel

I am guessing the instructions are the same for the 240D that has a similar Timing Chain Tehsioner.

Evidently you find a Can or Container big enough for the Tensioner to be put in with the Plunger facing up and deep enough so that when you fill the Can with Oil the Oil level is higher thant the Oil Feed/Inlet hole and simply compress the Plunger and down and release it and allow the oil to be sucked in.

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84 300D, 82 Volvo 244Gl Diesel

It's out of the 190 factory service manual. Says to fill the reservoir or something like that with oil, depress tensioner to get bubbles out and repeat until no more bubbles. Problem is they don’t mention where that hole is and I was looking for a larger place to add oil.

Quote:

Originally Posted by junkscouts My question is how does the 220D tensioner work? The manual from the 190D says the tensioner functions from oil pressure and you have to bleed it, but the 220D tensioner doesn’t appear to use oil as far as I can tell by looking at it. I realize now I should change the tensioner anyway, but is it just a spring in the tensioner or is there oil in there? It seams very slack right now, I can easily push the tensioner back in with my finger and it is not keeping the chain tight at all when I turn the motor over by hand. Needless to say I won’t try and start it until I get that chain tight, but any help would be appreciated.

The tensioner has a spring in it and it is fed oil from the oil circuit. The inlet hole is larger than the outlet hole, so oil is kept under pressure in the tensioner. You fill the tensioner before installing (as described above), but after that, it is kept full of oil and free of air by means of the oil pump. It works indeed slightly differently from the OM621 version.

Quote:

Originally Posted by junkscouts Also I was wondering about the injection pump timing. There didn’t seem to be any marks for lining up the sprocket (and nothing in the 190 manual) and the old chain was completely off so I just put the new chain on lining up the crank and cam marks, but now I am wondering if I will have to pull the pump to get the timing right? If that’s the case can someone give me a quick description of how to do that? ie lining things up, I can remove the pump easy enough.

Since the head has been off, it is best to take off the injection pump. Put the engine on 24 degrees before TDC in the compression stroke, line up the marks on the injection pump and install the pump. After that the pump needs to be fine-tuned by means of the drip tube. That is described in the service manual of the OM621. Copper washer (#5) has to be replaced (one-use only). This is a special washer, a generic one cannot be used.

Quote:

Originally Posted by junkscouts My last question is where on the block are the numbers stamped? When I looked up the new tensioner it wants to know “Engine Range: From 10-166609” so I’m wondering where I find those numbers?

The engine number is just below the text "engine number" in the picture below.

Thanks for all the help, and especially thank you Govert for mentioning that it is 24 degrees for a 220 as opposed to the 26 degrees my 190 manual tells me to use. I guess it makes sense since I had to cut two links off the 190 chain to use it on the 220. I pulled the pump, aligned the marks and all went back together easily.

I did pull the tensioner out and prime it in a can of oil and it worked like a charm.

The numbers on the block behind the injection pump (on a riveted on aluminum plate) are 5246 220D 275100. Unfortunately I haven’t found anything that tells me how to determine the year of the motor from these numbers. Can anyone tell me?

Everything is back together and I’ve got fuel to the pump and the lift pump is working, but I’m getting no fuel out of the injector lines, but I am going to start a new thread right now with all the details.

Thanks again for all the help.

Sven