Wonder if this was a previous owner vac pump earlier repair job...... someone maybe took the bolt loose not knowing and did not tighten correctly...?
I took my IP timing from stop to stop as an experiment and not much changed as far as general engine running is concerned....
I do not see where timing advance or retard would make any load difference on the IP torque demand....of course I might be wrong about that....looks like the IP torque load would be dependent upon rack position...heavy fuel demand would need longer duration plunger stroke...unsure if time of delivery would affect torque load on the timing device and intermediate shaft key
Some knowlegeable IP folks would know more about this than me.......
Still kind of a mystery failure...???

__________________
1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

I think there is a little hold bolt on the housing around the Timing device....best to get as much info on this as possible before removing the device....

__________________
1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

It seems to me it was probably a progressive failure that eventually just let go totally. This timing advance mechanisim is little mentioned in posts. I have wondered if the original calibration changes with age. I asked metric motors if they changed springs during their engine rebuilds with no responce.

Removal of the chain tensioner will probably give you enough room to insert enough screwdrivers to pull it out. If not tying the chain to the camshaft sprocket and sliding it off will certainly give you enough. Remember to plug the passage to the crank as the washer on the cam may drop in otherwise.

During rapid factory assembly the device is refferenced to the crank so I would look for marks. If none they could have performed the refference by plugging a temporary device into the timing advance devices splines. The loose metal generated by the destruction will probably not be harmful. Could have been something far worse quite easily.

finally got the timing device off. never as easy as it looks Below are pics. The end that drives the IP is sheared, the timing device looks salvagable, however there is suspect damage on the teeth where the device was probably cockeyed and the chain wore off part of the teeth. I'll probably end up replacing it too, just to be on the safe side.

Here is my theory, after tearing it all apart and seeing how everything works. The bolt that holds the timing device on became loose over time, when i revved up the engine the device was torqued over because there wasn't a bolt holding it snug, the chain caught a tooth, torqued it over even more and sheared the shaft that drives the IP.

Is the salvage yard the only good source for these parts?


.

Attached Thumbnails

       

Very valuable forensics. Someone here might have one on an old block they are willing to part with.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

A salvage yard is the best bet for the money....buying these parts new will be lots of $$$$....I would also put on a new chain and tensioners while its apart since hard to tell if any chain damage occured....that shaft is sold as a two-shaft set new I think....you want to make sure the other oil pump shaft geared to your broken shaft is ok.....probably best to change it too....drop the oil pan also to check for debris...

May be best to get a whole engine for parts if possible since you may need other parts during the repair....You can rebuild it at your leisure as an eventual replacement......This is an oddball failure.....just plain bad luck...these old things can throw some odd challenges at us......keep us posted.....forum members here may have some sources for used parts if they read this thread.....

Great autopsy pictures !...great info about this engine area....close up damage views are always a gruesome, helpful attraction....

But a hard, miserable way for the poor Diesel-Benz owner to provide info.....

__________________
1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

Don't forget to replace the Shaft Bushing in the block with new ones.

__________________
84 300D, 82 Volvo 244Gl Diesel

a question about the oil pump shaft. I can't find any info on it other than one diagram on the Haynes manual of it being there, not how to get to it or if it exists on my car. I don't see it in the hole, so either it broke and dropped down somewhere or it wasn't there in the first place. Would it not being there in the first place be possible? I wouldn't think they would put a gear there on the intermediate shaft if it wasn't needed. However on the M/B manual it mentions: "On engine 617.950 since Aug 1978, and on engines 617.951/952 since start of series, the intermediate sprocket shaft (B) and the rear bearing bushing (B) of engines 615, 616 and 617.912 are installed for reasons of standardization." maybe (here is hoping) the gear isn't needed on my car? I was about to put the parts I got in until I got yellit's post.

update, did some searching in the forum and found a thread about the oil pump shaft, also called the helical gear in the Haynes manual, and the turbo models have the pump driven by a chain and the non-turbo models have the oil pump driven by this helical gear. hopefully this is correct. I'll slap the parts in and check the forum if I get as far as getting ready to start the engine up later on today. hopefully somebody can verify that is true and my car doesn't have an oil pump shaft.

Got back to working on this car. update, after I got the IP timing device in the timing chain snapped, dumb mistake, trying to bump the starter around to make sure everything was ok before putting it all together. I don't *believe* that I harmed anything since the engine wasn't going around at all when the timing chain snapped. Guess time will tell once I get it all back together. So got a new chain, got the oil pan dropped and I've got the chain down the drivers side of the engine and to the crankshaft sprocket. Tried and tried various and sundry things to get the chain fed across the bottom of the sprocket so I could snag it and get it around up the passenger side of the motor. The manual says attach to old chain and run it around, however that isn't possible. Anybody ever put a chain in w/o the old one? Any tricks? Do I need to pull the oil pump? If so, how do I do that? I can't find any obvious methods in the manuals I've looked over. Thanks for any help.

you should not be getting this far into the engine without some form of factory service manual.

__________________

this is an interference engine, if you snapped the chain while you were cranking, you could have busted a valve. They are brittle.

send a couple of feet of mechanics wire down the passenger side and attach to the chain. There are a series of guides in the timing cavity that the chain must go through (b/w rails !!!) How do you know you are getting the chain b/w them? Can you see?

__________________

I can see most of the pathways either directly or indirectly. I would send wire down the passenger side once I could feed enough of the chain across the bottom of the crank sprocket. However I can't seem to feed enough of the chain across, it seems to get bunched up right below the sprocket and won't feed on over. I've hooked the end of the chain and pulled on it pretty good but it wouldn't ever feed across.

there should be no reason to remove the oil pump unless you have no room to work. If you manage to get a length of mech.'s wire down there (after you REMOVE the tensioner), there should be room enough to wire the chain up.

Your next issue is syncronizing the cam and crank now that their relation is lost.

crank @ 0 degrees on the balancer.. matched PRECISELY w/ the very tiny hatch mark at the cam behind the sprocket. (or use a dial guage in the cylinder for a more accurate reading of TDC)

you really need a manual

__________________

you mean it won't feed across w/o turning the crank..? or at all?

__________________