Nice feeling having my oil lines done... scenery on long runs is a lot nicer than an oil pressure gauge.

Been thinking about the other two potential grenades in my engine bay: timing chain and vacuum pump.

I check chain stretch every valve adjustment. Though at 41 years and 230k miles, I suppose the preemptive thing here would be to change it. I don't know what to expect.

What's been the consensus approach here?


Ditto for vacuum pump. That thing grenading ball bearing into my timing chain would be a disaster, though rebuild kits for bearing arm appear NLA.

What's been best practice here?


Be great to get on top of something if I can, though not wanting to rush pellmell into sleeping dogs and possibly shoddier replacement parts than their hardworking originals.


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1981 240D 4sp manual. Ivory White.

If it is a clean car that you want to keep, replace the chain, tensioner, chain guides and pump. I've seen chains break on a few 240's. It isn't hard to replace once you locate a crimping tool.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Oil pump too??

And what are people doing about vacuum pumps these days?

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1981 240D 4sp manual. Ivory White.

No to the oil pump.

I don't know for the vacuum pump. An option could be to dummy the pump and hide/add an electric pump, definitely not OE but...

Good luck!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

I replaced my 240d vacuum pump with an electric. never looking back.
You'll need a relay and a vacuum switch that T's into the hose.
I used a gm clone vacuum boost pump. it only runs a few seconds when I turn the key. I used a block off plate from doomsday diesel.

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1977 240D auto w/OM616.916 engine
2005 Matrix 5spd
2006 Prius

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You mentioned a pump in your first post. If not oil, which pump were you referring to?

Electric vac is a cool idea though tbh I much prefer the elegance of a critical system that does not require power.
I lost an alternator once and proceeded to drive six hours without issue.
Losing brake assist wouldn’t have been fun.

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1981 240D 4sp manual. Ivory White.

In the initial post I was referring to the vacuum pump.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Got it.

I’d really like to rebuild, though 6 ball bearings appear to be scarce.

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1981 240D 4sp manual. Ivory White.

According to this guide it looks like you have to do a decent amount of work including removing the fan and loosening the power steering pump to get access to the pump. it could be worth just replacing the whole assembly

-Matt

I appreciate it Matt.

Though as much as I enjoy firing the parts cannon and shopping with Pelican, removing the pump is a 15 min job… Like the majority of posters on your boards, I’m a hobbyist where time over dollars, is kind of the point.

Rebuilds are both fun and satisfying.

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1981 240D 4sp manual. Ivory White.

I’ve had the pumps out on all my cars. It is pretty easy. Do it when you change belts or when you go after the crank seal, power steering pump seal or vacuum pump seal.

For some reason the vacuum pump gasket leaked on all my cars.

I read all about the bearing replacement years ago. I’m not too sure I like the idea of replacing the bearing with a sealed or shielded bearing. My observation in there is that he bearing is splashed with motor oil. It’s not a sealed annular packed with grease.

I decided to check for play and go on with life. My bearings were in good shape. No sign of falling apart.

I do think it’s a good idea to go in there and look at the bearings and swashplate at least once in awhile.

The chain I’ve left alone. I’m kind of scared of messing with that. I’ve heard of people grenadine their engines right after a timing chain job. Probably because they didn’t properly form their rivet.

I have a sneaking suspicion these two diesels I own will outlast me the way they are.

Glad the oil lines are working out. I have pretty much the same setup as you.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

The oil lines are great… was very happy to strike that one.

Re: checking bearing play and “swashplate.” What exactly were you looking at?
I’ll be removing my PS belt soon to install a new AC compressor. Perfect time to take a look in there.

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1981 240D 4sp manual. Ivory White.

The swash plate is the wavy drum that rotates in the engine and pushes the pump in and out. The little annular bearings ride on it. To check the play I just hold them in my fingers and wiggle the races side to side. They should have little or no side to side play. Kind of like a skate wheel. You want it to roll freely but not wobble on the axel.

Any detectable wobble and I’d replace them.

The other mode of failure is the arm fracturing. I’m not sure how to gauge this but I did check for visible fractures. They may break when something else is out of whack like worn bearings or the endplay of the swash plate is too large.

Check for scoring on the swash plate surface.

Oops, it’s called the “timing device”. Misguided calling it a swash plate.

OM606 Vacuum Pump

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

Ah, thanks for that… not sure I’ll be able to gauge end play on the timing device, but I can certainly inspect the surface.

So I take it you’ve yet to replace the bearings on any of your pumps?

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1981 240D 4sp manual. Ivory White.

Never replaced them. They were in good shape. My cars are middle aged. At some point they may need bearings.

Mine feel brand new for all intents and purposes. No reason to change them.

Which makes me wonder why we see the failures. There could be variation in the suppliers MB used. Also the bad bearings may be a symptom of something else. Like letting the oil run low or not changing it for extended periods. The original design is un shielded and looks like it’s splashed with engine oil. It’s all wet when you pull it out and the gasket certainly is there to hold back oil.

My thinking is they fail because PO’s abused the cars. Like the timing devices in the GSXR photos. How did that happen? That isn’t normal wear. Or maybe it’s driving around with a big vacuum leak all the time?

There seems to be a lot of variability in the amount of wear one discovers when pulling the pump.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles