250 SL AT Shifts Problems

[FEDJA]

I just purchased a 250SL  and it shifts smoothly from 1st to 2nd and 2nd to 3rd but from third gear to 4th is shifts only at about 4000 RPM.  Any ideas how to fix this? I think the three part solenoid thats on the transmission might be inoperable.  If so I am not sure why I am able to shift normally from 1st to 2nd and  2nd to 3rd.


Also I have noticed that when I put the transmission shifter in 1st gear  it rolls as soon as I lift my foot off the brake without needing to apply gas.  Same for 2nd gear.  But when I put it in position 4, it wont roll unless I apply gas.  Not sure if the two problems are related.

[w113dude]

Try this link first, it's always good to know a bit about this transmissions.
http://www.sl113.org/wiki/Automatic/Start

As for the second part of your qustion, when you first start the car it idles at about 1300 RPM for a few minutes till the engine warms up then it drops down to 750 RPM, so when you put the car in gear at higher RPM it would move forward without the use of your gas peddle.

[ctaylor738]

It sounds to me like you need to have someone familiar with these transmissions adjust the modulator pressure.  This is a two step process, first adjusting the length of the linkage rod between the modulator and the solenoid, and then adjusting the modulator itself.  It needs to be done with a gauge to get the basics right, then a series of drive/adjust to fine-tune it.

[mdsalemi]

Also I have noticed that when I put the transmission shifter in 1st gear  it rolls as soon as I lift my foot off the brake without needing to apply gas.  Same for 2nd gear.  But when I put it in position 4, it wont roll unless I apply gas.  Not sure if the two problems are related.

Remember this is a 4-speed automatic, and under normal circumstances you are only using 2-3-4, not 1.  In normal position 4 (equivalent to "D" on other cars) you are starting in 2nd gear.  First gear is quite low, so low as to be nearly unnecessary and unusable (unless you are towing in the mountains!)  It doesn't make much to get the car to move in first gear, so while I can't say as I mirror your problem (I never, ever use 1st gear or positions other than 4 or 3 for a downshift at speed) I can see how it might happen.  We're kind of flat here in Michigan...