Tranny Question - PeachParts Mercedes-Benz Forum

mjquillici · #1 12-17-2008, 11:06 AM

I just had the transmission fluid changed in my 82 240D yesterday. I don't know or have any record of how long it had been since it was changed last - let's just say it was a loooong time ago. This morning, I found that my shifts from first to second are pretty rough when the car is cold. Nothing's grinding, but it's not a smooth shift anymore, and this had never been a problem before. Once the car warmed up, it was back to normal and nice and smooth. It's the original transmission. Any ideas about what might be up or how to get it back to a smooth cold shift?

Thanks,
Mike

bob_98sr5 · #2 12-17-2008, 12:39 PM

Mike,

Let me preface that I am not the expert here, but i did read a ton of info here, emailed a few guys, and got my shifts oh so silky smooth

Did they change out the trans filter? Hopefully so. And did this occur all of a sudden after the fluid change? Meaning, were your shifts silky smooth before the change?

I'm not familiar w/ the vac system in 82s, but the principles below will probably be the same:

- what is the vac reading on the line that goes to the transmission modulator? If you have rough, harsh shifts, see if increasing the vac to the trans modulator helps. You can increase it from the VCV or the blue ufo (if you have one). The other option is to turn the modulator CCW to soften the shifts. but if it shifts that hard, try the first two options.

- Check out dieselgiant.com's website. I recall he has a good page on transmission reconditioning.

- there's a very, very long but informative thread here called "It's Critical..." by Samuel Ross. Takes a while to get through it, but its well worth the read. Jeremy wrote a really good summary on page 9 or 10 which describes how the vac system works. I distincly remember reading something he wrote about how when the engine temp is below normal operating temperature, the coolant temp gauge turns the VCV (hopefully i'm remembering this right) vac off so that more vac will be received from another device. So if that is the case, then you would want to make sure that the 2nd device (sorry, drawing a blank on the name of the device) has a high enough vac to soften your shifts.

Bob

mjquillici · #3 12-17-2008, 01:06 PM

Hi Bob,

Thank you for your information. I made a mistake, however, by not indicating that I have a manual tansmission, and that my rough shift is while moving the gear selector from first to second. I should have made this clear. My thanks and apologies.

Mike

Biodiesel300TD · #4 12-17-2008, 01:40 PM

You may have put in some heavier gear oil that would cause it to be a little stiffer until the transmission got warmed up. What fluid did you put in?

mjquillici · #5 12-17-2008, 01:48 PM

According to the invoice from the shop, it appears to be Dextron II.

mjquillici · #6 12-17-2008, 09:48 PM

Disregard my last post. As it turns out, my mechanic put in Lubro Moly LM 2048 75W-90 gear oil. I would imagine that this is much thicker than what was in there before, which would make sense. I'll try draining and refilling the transmission this weekend, with some ATF.

Skippy · #7 12-18-2008, 02:13 AM

I recall doing some research on here and finding old threads that state the metallurgy of something in our transmissions (can't remember which part) doesn't get along well with the composition of gear oil. They say long term use of gear oil can cause severe damage. Smack your mechanic. Dexron III ATF is what you want in there.