90 model mercedes 300sl trannie problem - PeachParts Mercedes-Benz Forum

#1 10-23-2002, 04:26 PM

Problem with 90 model Mercedes 300 sl automatic transmission 722-500 5 speed. This transmission starts off in second gear then shifts 3-4-5 if selector is in D range. Problem I am having is long 2-3 shift cold. After transmission finally makes 2-3 shift all other shifts seem to be fine. Now here is the CATCH even after unit is warm, turn key off just for 1-5 minutes, then start the engine and long 2-3 is right back until transmission shifts to 3rd then transmission shifts okay again. Any help n solving this problem would be greatly apprciated. Thank you.

mbdoc · #2 10-23-2002, 04:47 PM

The trans is designed to hold the shift only when cold!! There is a solenoid at the LEFT front of the transmission mounted to 2 small metal pipes, IF the wire becomes disconnected THEN............
AS long as it isn't a California version car, or the check engine light will come ON.

oldblue1 · #3 11-01-2002, 12:14 PM

Thanks for the suggestions. checked that solenoid...it's seems OK and no engine warning lights either.

Adjusted the Bowden cable a few turns.

Problem still around...sticking, or long shift between 2 - 3 shift.

oldblue1 · #4 11-29-2002, 09:54 PM

MB DOC,

I have been out looking at this solenoid again to make sure it was checked correctly.

I am presuming that there must be a way of testing this solenoid and the sensors that triggers this action?

The tranny seems to work as designed after the initial delay. That is: the delay is not present on subsequent 2 -3 shifts so long as I do not switch off the ignition.

If I switch off for longer than about 5 seconds, the car/tranny seems to "forget" that it has just been working fine, and reverts right back to this long 2 - 3 delay....EVEN IF THE CAR AND TRANSMISSION IS REALLY HOT.

I feel that there must be some sort of timing circuit or flag that is being reset everytime I switch off the ignition.

I can see the delay box on the driver's side of the tranny with a cable coming up to an area under the airfilter. There appears to be a connector block in this area at the Airfilter.

If I unplug this cable, should this effectively defeat the delay mechanism?

If this does not affect the incorrect delay operation, where should I look for the next clue?

Also, how does one get to this delay solenoid if I wanted to replace it? It seems the only way is from the bottom...are there any gotcha's I need to keep in mind when doing this?