My tranny always had a rough 1>2 shifting, then smooth 2>3 and 3>4; I had some issues with the tranny and I replaced it with a refurbished one. Now it's still rough on 1>2, it's smooth on 2>3 and it's rough on 3>4. Downshifting is always smooth. I've searched in the forums and some people had said that they bypassed the vacuum control valves on top of the engine (mine are fairly new, about 2 years old), but does that work? Or what should I do? To me, transmissions are still a dark and unknown realm...

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[/SIGPIC]~cirrusman

1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang"
[SIGPIC]




1983 Toyota Tercel (Tommy, The little Toyota that could)
1965 Ford F100 (Grandma Ford)
2005 Toyota Sienna (Elsa, Wife's ride)


Gone:
1988 Toyota Pickup
2004 Subaru Outback

1987 Cadillac Fleetwood Brougham
1986 Volvo 740 GL Station Wagon - Piece of junk.
1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P.
1987 Pontiac Fiero GT

The old transmission was probably fine....these trans need a lot of fine tuning before you can say its the trans fault...

If the car isn't running up to power you will have shifting issues....if the transmount is bad you will have shifing issues..if you have vacuum leaks you will have issues...

you must make sure you car is fully maintained and it is producing the correct power...this includes

adjusting all linkages to the fsm guide
confirm no fuel leaks, clogged filters, clogged tank screen
clean air filter
oil change
valves adjusted
turbo maintained
rack damper bolt
pressure relief valve

then you must replace worn out bushings
trans mount
engine mounts
shiftier bushings
throttle pivot bushing

an diff oil change can also help.

then you must go to the vacuum system
you must not have any vacuum leaks
check modulator

then if your car is equipped
adjust the bowden cable

you must also confirm the kick down switch and solenoid is working properly

all this stuff is very very time consuming but if you want a proper shifting transmission it must ALL be gone through..

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The old tranny was leaking from the front seal, rear seal and from the pan, I kept it to be able to play with it someday and learn from it, but it was a mess. Oil change is due, Air filter is new, valves recently adjusted, turbo looks clean and sounds properly nice. I'll check for vacuum leaks... Thanks for your input!

__________________
[/SIGPIC]~cirrusman

1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang"
[SIGPIC]




1983 Toyota Tercel (Tommy, The little Toyota that could)
1965 Ford F100 (Grandma Ford)
2005 Toyota Sienna (Elsa, Wife's ride)


Gone:
1988 Toyota Pickup
2004 Subaru Outback

1987 Cadillac Fleetwood Brougham
1986 Volvo 740 GL Station Wagon - Piece of junk.
1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P.
1987 Pontiac Fiero GT

Welcome to the dark and unknown realm club. There is precious little solid knowledge of these transmissions overall (though some good DIY stuff in some areas). Suggestions:

1. Check output of vacuum pump with a gauge (check where main vac line, the big one, enters the brake booster). You will need to buy a vacuum gauge, not expensive. If the vacuum is low, you need to rebuild the vacuum pump diaphragm (I have not done that version, only the earlier, but there is good DIY here).

2. Inspect all the rubber joints for the vacuum lines to ensure they are not cracked/broken, thus leaking. You can get new ones, not expensive.

3. Check that your transmission vacuum modulator is holding vacuum. You will need a Mityvac or clone vacuum pump for this. It isn't a bad investment if you own one of these cars. Do that by finding the black line that runs from the vacuum spiders down to the transmission and applying vacuum to it.

4. Assuming all the preceding are either ok, or have been rectified and the problem persists... check the vacuum control valve on the injection pump. (If you want to cheat, you can start with this, but you didn't hear it from me :0.) See this DIY: Transmission flaring or clunking? VCV DIY - Mercedes-Benz Forum

Good luck

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

That's some solid piece of information! Thanks!

__________________
[/SIGPIC]~cirrusman

1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang"
[SIGPIC]




1983 Toyota Tercel (Tommy, The little Toyota that could)
1965 Ford F100 (Grandma Ford)
2005 Toyota Sienna (Elsa, Wife's ride)


Gone:
1988 Toyota Pickup
2004 Subaru Outback

1987 Cadillac Fleetwood Brougham
1986 Volvo 740 GL Station Wagon - Piece of junk.
1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P.
1987 Pontiac Fiero GT

wow great tutorial... i was having crazy flaring...and adjusted the vcv..now its perfect...
thanks for such a great tutorial

Sun Valley Mercedes Transmissions located in Van Nuys, Ca has a terrific web site full of transmission information including techniques for various adjustments and various tips they have learned over the years.

I have no doubt whatsoever that many people have paid for a new or rebuilt transmission, when the only problem was bad vacuum.

I have been told not once but TWICE by so-called specialist mechanics that the VCV is 'useless' and 'doesn't do anything'. (Have also seen that posted on this forum.) So that is what I thought, until I read that writeup on BW.

Minsk, thanks for the comment but if you meant the link I posted, I cannot take credit for that... I did not write the VCV tutorial.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I glued 2 nickles together and drilled a hole to make the gauge discussed in the FSM. Its not exact but close. Weather is breaking and both cars need work.

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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.