Hello,

I bought a 83 300SD recently. I was told the trans was bad, but I thought I would look into it further. I drained the fluid which looked OK and removed the filter. It was clogged as bad as any trans filter I have seen. I replaced the filter and fluid. At first the car would not move as before I changed the filter, but as I shifted to drive and reverse it started moving. Before long it shifted in to gear without slipping, but it will not upshift.

It goes in reverse fine it also goes in drive, you can shift to a lower gear and move the selector up manually it just will not shift.

I disconnected the kick down switch under the accelerator, no change.

I checked the vacuum to the transmission, with the car running it's 16 in. Hg.

The Bowden cable appears to be connected.

The transmission doesn't appear to slip in the gears it has, how can I get it to upshift? We have had several of these MB Diesels and I've had hard shifts and slippage even some that wouldn't move at all, but never this.

I'm hoping someone has seen this before.

Thanks,

Does the Bowden cable move freely? How high an rpm have you pushed it to to get it to shift.

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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

The Bowden cable does move freely. The tach is not working all of the time. I took it up to 30 mph, from experience I would say the engine was turning around 3000 RPM.

Drive it around for a while and push it to some higher rpm's. I've had an SD fail to upshift because it had forgotten how. Once I pushed it, it regained it's memory.

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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

Some where on this site is a very good write up about setting up the transmission. I am not sure where it is but I have used it in the past with very good results.

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1983 300SD
200000miles

Diesel Vacuum system adjustments

722.3 and 722.416 series transmission adjustments

http://www.transtec.com/downloads/tech_inserts/mercedes/94654.pdf

http://www.europeantransmissions.com/Bulletin/DTC.merc/91-41.pdf

Somewhere I found several step by step procedure and the pressure/shift point specs.

Confirm what trans you have. The number is on the passenger side of the trans right above the oil pan.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Thanks Junkman for the great trani info. BUT if you drill our the orifice as described in the Sun Valley link the drilled bits will end up in the vacuum pump valves. Disconnect the line at the pump and booster and blow out after drilling. Better yet, enlarge the orifice with a hot 1/16" drill bit.
Keep the good stuff coming.

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1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

It might be a broken valve spring in the valve body which is accessible from the pan. Whenever I troubleshoot an internal problem I check these first. I have a friend who has a late shifting due to a broken spring

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1981 300SD 512k OM603

Have you changed the filter at all lately. My 85 did same thing coming home one day on interstate- after getting more reluctant to shift to high for some time. PO did not change filter on time..mechanic pulled pan, half had been sucked into somewhere..he cleaned valve body and all was well.

Ditto,

If your filter was clogged that badly, I'm betting more cleaning is needed. The pan only holds a couple of quarts of fluid. You might try draining and replenishing a couple of times to see if you get a change in results.

If you remove the valve body, here is a thread from whunter that will be helpful: 722.xxx transmission rebuild or valve body cleaning; mystery pin

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Sam

84 300SD 350K+ miles ( Blue Belle )

so is only running 1st or 2nd gear?

had experience with a 190e 2.6 , which didnt wanna shift, in the end the tranny was pulled as there is a plastic gear set in the back of trans as to run the centrifugal valve to regulate the shifting, since it doesnt spin the tranny has no way of know how fast is your car going.
the gear was changed and it started to change.
other than that I dont know what else to tell u.

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