300SDL still won't go into 3rd/4th after long storage

[New2MB]

My 1987 300SDL has been a 7 year on/off project for me, it's a long story obviously.

Anyhow, it hasn't been driven in about 7 years during which time I removed the transmission and engine from the car.

Before removing the transmission it was shifting just fine but had been neglected, the fluid was very dirty. I changed the fluid prior to transmission removal and it was still shifting as it should have.

While the transmission was out I replaced the front pump but did not remove anything else.

After re-installing it shifts nicely into second but just will not go beyond that. I can go about 45mph.

I have quadrulpe checked the fluid level, it was just changed.

I have disconnected the kickdown switch and slackened the Bowden cable.

I have removed the vacuum line going down to the transmission.

I have added Seafoam Trans Tune.

Still nothing.

My next move is internal to the transmission, correct?

The governor seems to be the next thing to look into based on my searches, what would you guys recommend I do?

[New2MB]

Well... anyone want to sell me a used tranny?

Someone offered me one last year for $200 in the Detroit area, guess I should have gone for it.

[kerry]

How many rpm's are you pushing it to to try to get it to shift? My daughter's 84SD has done that in the past. I took it on the highway and drove it for 3 or 4 miles at high rpm's and finally it shifted and remembered that it had another gear and started using it again. It's done this a couple of times.

[New2MB]

4500rpms, for a few miles.

I thought if anything was gummed up in there that the Trans Tune would have knocked it loose, it sure has on other transmissions I used it on.

[New2MB]

Doing some more reading and considering tearing into the governor for a cleaning.

Before I do that I read that the ATSG manual recommends checking regulating pressure.

Can anyone tell me how this is done? Or should I even bother considering that it shifts from 1st to 2nd? Perhaps the 2-3 shift requires greater pressure that is not being developed.

[hughet]

I went through this a few years ago. Look at my post in October 2007 for the details.

If you drop the valve body and remove the top plate you will see two small conical screens that are probably clogged with a black powdery debris that comes from the clutch packs when the wear. Clean the screens and put it back together and your car will probably shift again.

You can probably do the job in about an hour and a half. It sounds scary but it is not all that tough to do. Jack up the car, drain the pan, remove the pan and let it drip for a while. You drop the valve body by unscrewing about 19 10 mm bolts. With the valve body out unscrew 3 screws and remove the top plate. When you do that you will see the two screens that you need to remove. Flush the screens with brake cleaner and reassemble. You will need to torque the bolts to 10 foot-pounds.

Put the transmission pan back on and refill. Then take it out for a drive.

Good luck.

[derick33]

- Did you find a solution?