95 e300d shifting really hard

[Jonsirr]

I recently went through the fuel system on this car, and now that I have it back on the road the transmission is shifting really hard. It's noticed primarily at lower rmp's, during normal driving conditions. At WOT the hard shifts aren't quite so noticeable.

Any suggestions? This issue basically started out of the blue.

Jon

[Zulfiqar]

if you were working near the pump you might have knocked out the modulator vacuum line.

You might also might have disturbed the vacuum hose that goes to the saucer type thing that is mounted on the chassis leg under the air filter box. It shares the same vacuum source as the vacuum control thing on the pump uses.

[Jonsirr]

Zulfigar, to the rescue yet again. I guess I'll take a look around for any vacuum lines out of place. The car was shifting beautifully before.

[andrewjtx]

Did you remove the crossover pipe or the intake manifold?

There are two resonance flaps that are controlled by vacuum there. I forgot to hook up the one for the crossover pipe one recently and needed to have 3 fillings replaced...

[Jonsirr]

Originally Posted by andrewjtx

Did you remove the crossover pipe or the intake manifold?

There are two resonance flaps that are controlled by vacuum there. I forgot to hook up the one for the crossover pipe one recently and needed to have 3 fillings replaced...

It's funny you mentioned the crossover pipe. Before I did any work on the car, it was extremely under powered but shifted really smooth. When I bought it the vacuum line to the crossover was missing. During reassembly I routed the hose back to the manifold itself. The engine runs much better, but again the transmission is shifting ridiculously firm.

I may have routed the line improperly.

This car has been a headache haha.

[shertex]

Certainly sounds vacuum related.

[shingleback]

Most 'shift problems' on those cars can be traced back to vacuum issues.

[Zulfiqar]

the vacuum lines for this car are quite simple but one or two really are a royal pain in the backside to repair.

The vacuum pods of the crossover and manifold are activated by 2 vacuum solenoids bolted on the intake manifold. They share a common vacuum source and also a common "vent" source which snakes up and behind the brake booster into the car where it just hangs around (its a vent and the cab has clean air)

I had the red vacuum line that goes to the vacuum tank in the right fender break somewhere ahead of the blower motor case. It was giving me grief. I capped it and ran the car for about half a year and then I had to undo the blower case to oil the motor. I repaired the line with a rubber piece and I could actually reach and see the other end now. This connection further helped the car smooth out the vacuum functions and shift quality later after a trans service the car glided into gears.

In short - if your trans shifts hard for no given reason check the vacuum lines first, its a closed forest of lines, any leak will vent the system and give you grief.

[Chris W.]

As Zulfi and other say, this is absolutely a vacuum issue. On my car I had done some work on the engine and was moving vac lines to see better and get better access. I unknowingly cracked a Y fitting and that was enough to make the car shift hard. You will just have to do some detective work to find either a disconnected line or a cracked fitting.

Rgds,
Chris W.
'95 E300D, 408K

[Jonsirr]

So I'm just now addressing the issue of my hard shift, and I believe I found the/a vacuum leak under the hood that caused my sudden onset of hard shifting. This picture was taken from above, looking down between the crossover and the IM.

Does anyone know what the function of that green cylindrical device is?

Jon