'90 300E - Trans sometimes not engaging OD

[Andy_M]

On my wife's 90' 300E the trans shifts like a champ, but sometimes will not engage overdrive. Shifts and acts just fine other than that issue. Stop the car at a store or something where you shut it off and restart it, and it usually will start engaging OD again. Sometimes starts engaging OD after it has warmed up good...other times waits for a off/on cycle.

Fluid is full, appears to be clean and smells ok. All other shifting is ok, so I doubt it is a dirty filter or bad modulator. Is there a throttle position cable or a position sensor that might cause this type of behavior ? Vacuum line somewhere ?

[babymog]

There is no 90' 300E, I believe that they're closer to 16' long.

Also, you don't have overdrive, only a 1:1 4th gear unless you have a 5speed manual transmission.

Sounds like a classic symptom of a clogged transmission filter, which further indicates that either the fluid changes are severly neglected, or there is more friction material in the fluid than normal which might mean it's slipping and on its way out.

Try a fluid and filter change, including the TC, see how it goes. Make note of the amount and color of sediment found in the pan.

[Andy_M]

Thanks Babymog.....will change fluid/filter.

For anyone.......Besides MB, what trans fluid can be used? Royal Purple? Other synthetics? What do people use in these ?

[david s poole]

your problem is caused by a clogged small filter in the passage that supplies fluid to the govenor it is accessable by dropping pan and removing both valve bodies[main and small] along with the separator plate.it will be contaminated by clutch debris and if you clean will have trans back to normal.

[Andy_M]

Fluid change and filter did the trick boys...filter seemed fairly clogged. I had let the trans drain for a good 10 mins before I pulled the filter off, and when I did, another quart or more of fluid came gushing out. Pan and fluid was quite clean though....


Thanks for the replys.