Hello, I've had my 81 300TD for a few years now, (about 200k+) but have spent most of my time working on it and have only put about 5k on her. She's a driver, but presents herself pretty well & am looking to get the old girl sorted for the long term. Developed a tick last fall & immediately parked her as I suspected the vacuum pump. Pulled the pump yesterday, rocker arm tip bearing scattered, balls gone. End play on shaft is .33mm, well out of spec. I know I'm looking at minimum replacing shaft bushing and gaskets, as I do have a relatively low mileage SD from which I can scavenge parts. I've tried to plow through posts here to get an idea of what I'm up against, but still a little skittish about tearing her down. I'm gathering that I need to pull the injection pump, valve cover & tensioner to remove timing device. Probably set engine to TDC before I go any further?
I was going to have the injectors rebuilt & balanced anyway, is now a good time to do timing chain & guides? I did check it for stretch when I adjusted the valves and it was good. No idea if it was ever changed. Will pulling the radiator give me enough room to do all this with the engine in the car? I'm pretty handy, but have to say these little diesels are intimidating. Are there any good write-ups on doing this bushing and what's involved or should I just stick with the manual? I would imagine just about everyone has to deal with this at some point. Any guidance will be appreciated Thanks, Mike

You'll wish you did- if you damage it while working you'll have another thing that needs immediate attention.
I wouldn't necessarily source a used timing device bushing- It could be 1 week away from being as loose as the one you are replacing. A new bushing fits the shaft smartly. The overall length I measured on mine was around .840" , if you measure your replacement part, just make sure it isn't worn out, or nearly so.
If you are going in there, you would serve yourself well to change out the guide rails, tensioner rail, and chain tensioner.
Behind the timing device bushing, the intermediate shaft had a gear on it that meshes with a near-vertical shaft that drives the oil pump. The thrust bushing on this becomes worn, and the gear in thrust will ride up into the "thrust piece", damaging the gears, and possibly grinding up so far that the gears disengage, leaving you with no oil pressure, in spite of a pristine oil pump and a full charge of fresh oil. The replacement cost (new) is $1400 and UP for the replacement intermediate shaft and oil pump drive shaft, sold only as a set. My gears are in good condition, but there was a lot of wear on the thrust piece, and it needed to be replaced. Found one on E-gouge for about $18 shipped. I would rather pay that than for the alternative. You can also find used shafts, but they are $100 and up for each of them.
One thing I didn't do on my "front engine job" (that started out as checking timing chain stretch) was spring for the Mercedes rail pin puller. After the gynastics, gnarled threads, sawing and trimming all-thread, I will buy a puller. I surrender. Most of my time was trying to make bolts, nuts, washers and sleeves for pulling the rails, rather than getting them pulled.

I am still cleaning up after this job. I have a noise that I haven't determined the cause of yet; the car idles nicely, starts easily, and I haven't even adjusted the valves (they are overdue) but I have a sound that seems to be something that was dropped into the engine before I started it. It sounds like a piece of coat hanger wire. Or maybe an entire breadpan- until I search this out, it could be nearly anything!

My cuurently "living" thread is here-

http://www.peachparts.com/shopforum/diesel-discussion/378205-1979-240d-checking-chain-stretch.html

It's long. It got a life all it's own.


Cheers!

snapped_bolt

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'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

Snapped Bolt, Thanks 4 the response. I read the entire thread, wow. I'm hoping all is well with the engine & you get to drive it again soon. I'm hoping mine goes a little smoother. I'm still unsure of the sequence to go about doing the bushing replacement, especially if I'm doing rails, guides & chain. I'll do a little more digging on what's involved. Thanks, Mike

There is no mistaking my irrefutable method of finding a way to compound the profanely simple
But we have to get there somehow.
You should be able to get through this without injury!

snapped_bolt

__________________
'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

Maybe it is time to find either an online source of the Factory Service Manual or buy one of the Mercedes Service Manual CDs. Instructions would be similar to removing the Timer.
I am not sure that you need to pull the Fuel Injection pump to get at that particular Bushing. However Pulling the Fuel Injection Pump would also allow you to look at the bushing on the other end of the shaft.

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84 300D, 82 Volvo 244Gl Diesel

can remain untouched. I removed mine to replace the leaking gasket.


snapped_bolt

__________________
'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

I do have a MB manual on cd, I will start digging. My lateral play didn't seem to bad, but the thrust surfaces are certainly wore at .33mm. I want to approach this repair in a logical manner & I hate to tear half the engine down in one shot, but if I'm doubling my work by doing one thing at a time, I'm all ears. I know my chain is within spec on stretch, but wouldn't mind knowing the condition of the tensioner, guide rails & such. I know the timing device is a pita to remove because of the timing chain, but losing the routing of the chain or completely dropping it scares me a little. Pulling the IP doesn't scare me, but timing it properly does a little. At this point in the season I'm not in a rippin hurry to get the car going again as I would only drive it for a couple months. (I live in THE rust belt of the world just south of Buffalo, NY) By the same token, I hate tearing something apart & trying to get back in it's groove a month or two down the road. Man, I really like this car & was tickled to death when I heard they were one of the most durable, reliable cars ever built. Nobody told me it wasn't without effort & a bucket of money. Car originally came from CA, but there was still a lot of hidden water damage. (Did a bit of bodywork in all the typical areas) I've gone through the SLS, replaced oil cooler lines, front suspension, brakes, and a lot of other typical stuff. I'm in it too far to quit! I feel I'm at the bottom of a long list of folks that have been there, done that.

agreed.

no need to pull the IP.

And, get a copy of the manual. THEN ask more direct questions.

forum correspondence is a breeding ground for confusion unless you know what you are looking for.

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Honestly, the plastic guide rails can be ignored if you want to save some time and energy. they might have big gouges in them, but there's plenty o meat there.

the tensioner rail though, thats a different beast. replace it if there is any slop in its motion or the running surface feels like the inside of gramma's oven that hasnt been cleaned since 1920. -it should be a bit soft, like it could absorb shock / impact.

Can't drop the chain in such a manner that it isnt retrievable. theres always a way to fix "fk'd" in this case.

as soon as it is free, weave a metal wire about 2 feet long through some of the links. -you're set.

timing device is annoying, but you cant really fk much up other than IP timing. (and maybe pulling the pins)


...
you might feel at the bottom, but your willingness keeps you far above that. Just gotta learn your own way. and before all of us shadetree knowitalls... there were well-paid techs at MB who knew the same or better, at times. we are all in line.

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Ok, stumbled across this thread while getting an idea of the chain routing.
http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html
Wow, exactly what I was looking for, Thank you Cell! He made all of the mistakes I would have & still managed to get it done. While the most effective way to learn is from mistakes, it is far less painful if you can learn from someone else's! This write-up is awesome, I think between the fsm & this I should be able to do what I'm trying to get done. Although I'm a little envious of all the room that a 67 pickup affords! I'm not usually this gun-shy about diving into a repair, but I certainly realize that not paying attention to detail and doing something stupid on internals can cost you an engine real quick. Damn, I just put a new lower pan and gasket on when I did my turbo drain, probably going to have to pull it to see if I can find those "twelve little balls"

Not in my 1984 300D. The oil pump is driven by a small chain off the crankshaft. I think all turbo versions are like that. The OP's 1981 could be turbo or not. All 1982-85 in the U.S. were turbo. BTW, you don't need to remove the upper oil pan to replace the oil pump, as some say. I did so w/ engine in car, but only to replace the broken plastic chain tensioner which installs on the main bearing cap.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

very true. turbos have a different setup.


Bill, how did you pull the oil pump sprocket with the upper pan on? that thing never comes off for me without a puller.

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Ran across Cells's thread "9 degrees of timing chain stretch", GREAT write-up with photos. THANKS for the effort & cleared up a few questions I had. Jealous of the room he has in that 67 pickup! Looking at things it seems as though the sleeve will come out with the timing device & the bushing is held in place with a bolt to the block under the timing device. Is this pressed in and how difficult is she to pop with the shaft still in place? It looks as though it has flats or notches for a spanner to facilitate a little roundy round action. I do have the turbo, so I probably wont pull the IP if I not required. (If I didn't, I would just to inspect oil pump gears) When I do tear into it I will be sending my injectors to Greazer for rebuild. By spring I should be ready to find my next can o' worms? Thanks JT & maybe I'll reach out to you if I have to unfk something

is the best thing you can do, if you appreciate peace of mind.
Yesterday as I wrestled to remove the timing device (found that was unnecessary), I elected to first remove the idler sprocket to gain the slack needed to remove the timing device. I have a new chain tensioner installed, and it was a minor %^*$!! getting the cam sprocket off the cam because of the new tensioner- it steadfastly resisted my efforts, keeping tension on the timing chain. I used force to remove/reinstall the cam sprocket; I ended up rotating the cam with vise grips about 1/10° to re-align the Woodruff key.
This "non-turbo" tensioner definitely is no slacker (pun intended) when it comes to chain tension; I have every bit of confidence that it will be there doing it's job at every startup.
As I mentioned before, the thrust bushing, as well as the thrust piece on the oil shaft need to be checked; with that amount of miles, the thrust piece is either trashed, or it has been recently replaced. A new thrust piece will eliminate a possible source of racket.
If your chain is good, and not an issue at all, replacing the guide rails is OK as long as being in the "Rust Belt" has not rusted the pins in place. Mine weren't.
The best way to get the car on the road as soon as possible is order all of the parts you would like to replace all at once, and don't remove a single screw until you are ready. The total down time should be under a week if you take your time, make careful observations while you are in there.
I will now say that you might be served well by getting a Haynes manual.
While it often is the recipient of scoffing here, it does indeed supply pictures that are not found in the Mercedes Service Manual, which at times seems as if it were intended to be read by robots that are pre-programmed for the job.
So, getting your parts in hand before tearing into the job is best if you want "minimal" downtime.

snapped_bolt

__________________
'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

Wow, Just revisiting this... I just finished the intermediate shaft bushing. Not terrible, but a lot of disassembly for access. It's only been 3 years?!! Wow. I did find all twelve ball bearing in the pan and was able to scavenge a vacuum pump and rollercoaster cam off my parts car. They were pretty serviceable, I may spring for a rebuilt pump and new cam if everything else seems ok after a few thousand miles. On to a pinion seal & rebuilding the injectors!