transmission acting up
 

I have been tuning up my 78 300D and it's time to start worrying about the transmission. When I got the car it seemed to slam into gear (compared to my dad's buick). I knew mercedes shifted firm but it kept getting firmer. Eventually it has come to the point where 1-2 rattles your teeth, and that to shift from 2-3 and 3-4 I have to let off the accelerator for the tranny to shift. For example, on the highway today as a test I held the accelerator down to the floor accelerating up a hill in 3rd (I was merging) and the tranny would not shift til I let off the accelerator. I didn't need to keep off it just for a second til it shifted.

I'm not sure what the vacuum setup is for your model. Probably the first thing to do is obtain a diagram or take a look under the hood for a disconnected vacuum line.

(My experience is mostly with the W126.)

a friend of mine had a 1980 given to him because the owner thought the transmission was shot (and my friend tends to collect mercedes). turned out to be a vacuum line unattached due to a worn fitting.

At least your car is nice... :wacko:

there is no vacuum control for the transmission on '78 and '79. I have a '78 and had a '79. I would get harsh shifts if transmission oil was low. have you checked that? -Andy

How long has it been since you changed out the AFT? Should be changed every 30k. The transmission is the most neglected part of most cars and they are expensive to repair. If you do the change out yourself, it will only cost about $35.

I don't think it's ever been low or leaked. I remember looking at the ATF when I bought it but don't remeber what the level was. I will double check and let everyone know.

I checked the fluid level and it is actually way too high. Am I supposed to check this level with the car running? With the car in gear? I just checked it with the car off when I was filling up and the fluid level was about half a scale reading high. Please Advise.

Dan

The fluid level for an auto transmission needs to be checked when the fluid is warm, car running in Park, and on level ground.

Found tranny problem
 

Ok so I figured out my tranny issue. I had adjusted what I thought to be the low idle adjustment but it in reality was the throttle linkage. I was only getting about half of the available throttle :eek: :eek: :eek: . This must also adjust the tranny although I'm not sure how. After setting my throttle to get full available throw my tranny shifts like a dream.

Anyone know why/how this linkage adjusts the tranny. It is the linkage that goes down the air cleaner side of the valve cover.

Pics would be nice of what you adjusted, and also of the IP side.

will post pictures this after noon

An over filled transmission is not good, it causes the fluid to foam. Siphon off excess fluid thru the filler tube with 3/8 od tube, and check again.
I drain the trans. every third oil change, and add new fluid, costs about $8. in ATF, but it well worth it and is easy since you are under the car anyway, and it is cheap insurance, beats a $2000 rebuild.

Do you have an owner's manual for this car ? It's worth reading.

On your car and mine the throttle linkage is linked to the tranny,this is why adjustment is important. we do not have vacuum controls on our trannys.