Maybe there was an orifice of dirt at the T on the main vacuum line. It one time, I had very hard shifts because I had no vacuum to the tranny. Problem was total blockage of the T at the main vacuum line. Could partial blockage at this point have the same effect as an orifice?

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Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/showthread.php?t=296386

I thought the 3/2 valve had something to do with transmission shift also? Not true? As I recall, Dieselgiant's site has a procedure to replace the 3/2 valve to restore proper shifting? Curious why it is called the 3/2 valve. I still have mine. Going to get rid of it now.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

It depends on the vehicle. My comments are vehicle specific. You can remove the valves on the 300D turbo.........not on the 240.

Thanks Brian. Can you explain why?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

The 300 turbos use the vacuum strictly to control the speed of the shift........not the timing of the shift. They have a Bowden cable for that purpose.

The older systems used vacuum to control the speed of the shift and to also delay the shift depending on the vacuum level. They didn't have a Bowden cable.

So, certain older vehicles........240's for sure.......cannot have those valves removed without affecting the transmission performance. I'm really not certain of the years and models that are related to this situation, but I'd presume that for any vehicle without a Bowden cable, it will certainly be applicable.

Brian I am having trouble with my 81 300SD. The problem I am having is a kinda slow shift from 2-3 under heavy throt. and worse flaring when its shifting from 3-4. It seems to shift fine though when not under heavy acceleration. This all seemed to happen overnight, as the day before it shifted great until I went through water over the roadway.

Ideas?

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Regards,
Ian White

1995 E300 Diesel w124 OM606
2014 E550 w212 M278 biturbo

2001 BMW 740i E38 M62 (past)
1981 300SD w126 OM617 (past)

Cannot tell anything until you hook up a vacuum gauge to the modulator line and advise what you've got.

Read the gauge at idle and at various pedal positions while you drive it.

Brian,

Was driving on a main highway for about an hour at 70, entered the city and slowed to make a right turn. When accelerating(gently!) out of the turn, I heard/felt a clunk, a bang and it just flared like crazy. I could get it to move only if I revved to 3500-4000 rpm and then backed off a bit. It then slowly gathered speed enough to make it home(about 70 miles). Vacuum is good to the modulator, and the VCV leaks off from 12" to 5" in about 20-30 seconds. When I checked the fluid right after it happened(before returning home), it was 1/2" high on the dipstick and had some small bubbles. After returning home and letting things cool for a day, the fluid was where it should be and the color looked ok(red not brown). Also discinnected the vacuum line to the tranny and it seemed to move a little better, although still flaring badly. Ordered 2 AT filter kits yesterday and will change fluid/filter, add Trans-X, run engine for an hour or so, drain and change filter, fill with AutoZone Dexron III/mercon(only kind available locally) and hope for the best.
Question: Should I also try to get the K-1 and K-2 kits and install them at this time? If so, what are the p/n's for them. Thanks for any advice as the closest M-B dealer is in Tucson(500 mile round trip). I really hope that there is a solution other than a rebuilt tranny.

PS, haven't pulled pan yet to see if any strange pieces down there as only place to work is open to the wind and dust(it's Mexico) and when I do open it up, I will need to make some kind of wind/dust barrier.

Dave
'81 300SD
'81 VW diesel caddy

Car in my previous post with tranny problem is a '81 300 SD with 187k miles. Tranny is 722.303 02, s/n 073124 and is original trans(I think). Car was purchased 3 years ago with 153k miles. No idea who previous owner was as it had been a church donation for charity/fund raising sale.

Sorry 'bout that.....Dave

I believe we need to qualify "flare". When the transmission pulls properly in all gears, but disengages into a false neutral between gears, that's a "flare".

When the transmission won't pull the vehicle forward under normal revs.........and very high revs are used to move it........that's "slipping".........a completely different diagnosis.

It's important to state exactly what's happening with it and I don't believe it's a simple "flare".

If it won't easily move from a standing start in first and second gears, the problem is likely to be the B2 piston. Do some research on "B2 piston" and see if the symptoms are similar to what you've got.

Brian,

Thanks for your quick reply and clarification between "slipping" and "flare" as I thought they were the same. Anything else that you think I should check/replace, ie. K1-K2 kits? Do any of you out there on this thread have a p/n for the B2 piston parts(kit?)? I'll check back in after fluid/filter change and tell how that went. Will be going to the US sometime soon and will check M-B dealer for the parts unless you guys think ordering from Fastlane would be better and less expensive. Again thanks!

Dave

Brian,
B-2 piston came out in pieces. Rubber seal over bushing torn getting out, however the bushing(aluminum) is stuck and looks to be out of round. Is it a wise idea to try(very carefully) to cut it out using a very sharp knife, like a box knife? I don't want to take any chance of scoring the piston cylinder, but the bushing housing will have the new bushing covering any incidental scratches( hopefully Very few). Do you see any problems doing it this way and if so, any suggestions for getting that bushing out w/o damage? I have had no success trying to find a tool to remove that bushing locally. Again, thank you for all the help that you give us folks out here in the hinterland. I've learned more from your posts(and those of other members) than I ever have from just reading manuals. This forum is a treasure!
Dave

I've checked the sources in beginning part of the thread for a vacuum diagram. My car is a 1989 190D 2.5l automatic they don't list it. Anyone know where to get the diagram.

I change my oil and fuel filter and checked the air filter now I'm having shifting problems. Probably knocked or broke a vacuum line some where.

The transmission won't shift into high gear revs to 4500+ rpm


Thank You

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1989 Arctic White 190D 2.5l auto w/400E Brakes and a 5spd waiting for me to install

1977 280SL Euro M110/w 4spd

2001 Dodge Ram 2500 Quad cab 4x4
dyno 383hp / 916ft#'s

Find the kickdown switch beneath the accelerator pedal. Unlug the switch. Take the vehicle for a drive and see if it's cured.

WOW that was quick.

It was unplugged and I plugged back thinking it was the problem. It did get a little worse about revving. I'll unplug it but the shifting problem existed before I plugged it back in.

It would suddenly down shift for no apparent reason after car warmed up. Then it would not shift into high gear unless it revved then took foot off accelerator. Shifted into high for a less than a minute and down shift again

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1989 Arctic White 190D 2.5l auto w/400E Brakes and a 5spd waiting for me to install

1977 280SL Euro M110/w 4spd

2001 Dodge Ram 2500 Quad cab 4x4
dyno 383hp / 916ft#'s