Sealed bearings wouldn't make any difference as the bearings are lubricated by the engine oil. You do want to avoid the plastic/nylon caged bearings.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

You did not say if it is the down shifts that are hard, upshifts that are hard or both.

When my vacuum line to the transmission modulator got disconnected I had harsh down shifts but the upshifts were nearly normal.

There is no vacuum amplifier on my year and mode.

It would not hurt to inspect the bearing on the Vacuum Pump. If it is the bearing with the plastic cage you would to change it to a bearing with a steel cage.

__________________
84 300D, 82 Volvo 244Gl Diesel

That's what I thought .

I sometimes use sealed bearings in rear wheels as some oldies have mediocre designs that allow gear oil to weep out and contaminate the brakes, also in generators sealed seems to last longer than the original open bearings .

Good point about the metal cages ! .

LM brand bearings are to be avoided at all costs ~ not even for FREE .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

[QUOTE=Mike D;3875032]If it comes down to it, the pumps are rebuild-able, including replacing the bearings with improved, caged style bearings.

https://www.youtube.com/watch?v=DWvLY82zcFg/QUOTE]

That's a 617 pump, which is a very different design. I don't know of anyone who has rebuilt a 602/603 pump.

Here's a comparison of the bearings used in the old and new style vacuum pumps.

That video shows a 617 pump rebuild. Or did I miss something later in the video?

I haven’t seen parts or instructions to rebuild a 601/2/3 pump. Nor have I heard of the pump section fail. It’s usually external check valve seizure or drive section collapse - bearings or pivoting lever hinges come apart.

The early style crimped on cover can leak oil as the seal hardens. I haven’t seen the seal available separately but that would be a straightforward in situ repair.

Sixto
98 E320s sedan and wagon
02 C320 wagon

My mistake. I forgot the '91's had the OM603.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

What makes you prefer these solvent over brake cleaner?

__________________
1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

They are not as toxic or as harsh on my skin, lungs and liver. They take a bit longer to clean but they do not affect rubber seals, polished surfaces, etc.

Mostly personal preference.

Check out some of the results of long term exposure to those cleaners.

https://www.popsci.com/diy/article/2009-12/dont-get-careless

https://sciencing.com/ingredients-in-carburetor-cleaners-12080316.html

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Converted

__________________
1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

I've been telling folks to discard carby cleaner sprays for decades ~ it makes a bee line to your kidneys and liver, nothing good can come of it .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Downshifts are fine... always have been.

I did use my stethoscope on the vacuum pump and heard no odd noises or knocks.

I was set to do vac line testing this weekend, but just as suddenly as the harsh shifting appeared... it disappeared. My back being in a state of pain, I didn't do anything under the hood. In fact, I never even popped the hood... she just started shifting very normally on the drive home from work Friday night.

__________________
1991 300D 2.5 "Rocinante"
2002 Golf TDI "Teen Spirit"
--------------------
1984 300D
1966 Mustang I6 3sp
1985 Mazda RX-7 GSLSE
1982 Toyota Supra
1977 Datsun 280z
1971 Datsun 240z

I have ditched them and now am using industrial surfactants to clean greasy stuff, carby clean is still used if Im trying to remove shellac gasoline or other crap like varnish stuck on throttle bodies. - All others get the purple stuff from sams club or the orange stuff from homedepot with a lot of watering down.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

I use dishwashing detergent and water as my first step. Usually that's all that's required.

For the varishy stuff I use cheap, plain old Ether , starting fluid in a can .

Just work in a WELL VENTILATED AREA AND DON'T SMOKE , it'll be far safer than carby cleaner, you really don't need it , it -will- kill you, just slowly .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

got it, im ditching the carb cleaner.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)