w116 300sd won't get in gear

[2dads]

i was driving my 1980 w116 300sd last night and was backing out of a customer's driveway (i deliver pizza) when there was a noise under the car and it came out of gear in reverse. i couldn't get it in reverse or any moving gear and it just wasn't having it, so i pushed it into a parking spot on the street and walked a couple blocks to my apartment to grab another car.

the only gear it goes into now is park. i checked the transmission fluid and it didnt have anything in it and didn't smell burnt. i was in a hurry to get back to work so that was all i really had time to do before i dipped out.

the transmission always shifted fine, no flaring or anything. only issue it had was if i put the shifter into the reverse position it wouldnt go into reverse. i would have to move it slightly below the reverse position for it to engage in reverse.

since it still engages park it can't be the drive shaft right? the issue it had with the shifter and reverse previously makes me hope it could be the shifter or linkages, but i've never had to do any automatic transmission repairs.

what should i be looking for to diagnose the problem, assuming it isn't something that broke inside of the tranny itself.

thanks!

[Doktor Bert]

W116's (and others that used the 722.120 transmission) used to habitually back the reverse band nut off, which would disable reverse.

The B2 piston issue will disable forward speeds, but your problem definitely seems unique....

[The Gears]

Will the selector move as it did before?
Has any junk from the drive way flipped up into the shifter area?
Has the linkage just come loose?
Does the engine sound change when selecting different gears?
If the car is in motion or the drive shaft turned will that help?
Just some basic questions for a start point.
Could be the torque convertor and not the trani. I had your exact problem and the crooked trani guy tried to sell me a complete rebuild.

[kerry]

Originally Posted by 2dads

i checked the transmission fluid and it didnt have anything in it !

Are you saying there was no transmission fluid in it?

[Diesel911]

Ask Member Stretch on this one. I remember Him mentioning something go one of the Members about the Pump Drive going bad on the older Transmissions.

As the other member stated take a look at the linkages.

Could the Rear Transmission Mount or one of the Motor Mounts gone out?

[kerry]

116's are known to shear the ears off the front pump. Pull a cooler line with the engine running to see if it's pumping fluid.

[Squiggle Dog]

I have a 1980 300SD, and when I got it, it would not move under its own power unless the engine had been running for about 15 minutes. Once warmed up, it would work fine. I came to the conclusion that it was aged and shrunken seals in the transmission that wouldn't allow it to build enough pressure at first.

I replaced the transmission with a used unit, but had to swap out the bellhousings because the one on the replacement transmission was chewed up and had chunks missing caused by a broken flex disc. When I opened up my old one, I saw this:




The screws that held on the front pump had worked themselves loose and fallen off! So, this may have actually been the problem the whole time.

[Doktor Bert]

Any updates????

[Doktor Bert]

Originally Posted by 2dads

i checked the transmission fluid and it didnt have anything in it and didn't smell burnt....thanks!

That would be the first priority....getting fluid in it....just keep in mind a 722.120 will function even with no fluid showing on the stick.

[tyl604]

I think he meant that he did not see anything funny in the fluid like metal shavings, not that it was dry.

[Doktor Bert]

Updates????????