Shifting Symptom in SDL I'm Considering - PeachParts Mercedes-Benz Forum

shertex · #1 09-17-2012, 09:51 AM

Hi. There's an 87 300SDL I'm thinking about buying....I'll be seeing it in person this Friday. The owner has been very open and forthcoming about the car, which I very much appreciate.

The tranny has only 80k miles on it (car has 270k). The tranny is an MB remanufactured unit. The symptom is as follows: under moderate acceleration, there is a late 1-2 shift followed by a quick 2-3 shift; however, under hard acceleration the shifts are fine. As I don't know a lot about transmissions, I don't know how serious this is and what the potential causes might be. In my view, an MB reman unit with only 80k should be operating perfectly.

The owner has not changed the fluid and filter in 30-40k miles, so that clearly needs to be done. And he removed the ALDA some time ago, although the shifting symptom appeared only about a month ago.

Any ideas?

barry123400 · #2 09-17-2012, 11:24 AM

Since the transmission is capable of hard firm normal shifts with no abnormal slippage at more throttle. I would expect it to be an external transmission issue is more likely than internal. Does the selling price indicate the owner thinks the transmission is defective itself? One has to also consider the more remote possibility it may be internal as well. No absolute way one could gaurantee one from the other. You have to drive it yourself to determine if his description is totally accurate as well.

Stretch · #3 09-17-2012, 01:03 PM

From the information given my guess would be something along the lines of

1) New fluid and filter change - look for the obvious - loose connections etc and see if that helps

2) Check vacuum system and then Bowden cable adjustment

The thing is though, from what I've read in the FSM (and from the posts Govert makes), to do step 2 properly you ideally need to get a bit more involved with measuring transmission fluid pressure in addition to vacuum. I get the feeling most people don't do that (hence all of those threads about how to get a transmission to shift nicely)...

All in all it doesn't sound like a deal breaker to me. With care and attention I reckon it could be sorted out.

pawoSD · #4 09-17-2012, 06:02 PM

Thats typical of a leaking vacuum modulator, or leak in the line between the IP and the modulator....and/or also a bowden cable mis-adjustment.

netboy · #5 09-18-2012, 10:07 PM

I just increased the fuel flow in my 350SDL by shimming up the ALDA and it has caused my tranny to shift hard now. My guess is the tranny on your car is fine, your going to have to adjust the bowden cable, VCV, and check vac at the VCV. I have instructions to fine tune a tranny on a 617, but I'm in search of the info to tune a tranny on an SDL. Thats what you need also.

Hit Man X · #6 09-18-2012, 10:25 PM

Did you roll under the car to check for the black MB tag on the side of the case? To verify it is a factory reman...

shertex · #7 09-19-2012, 06:36 AM

Quote:

Originally Posted by netboy

I just increased the fuel flow in my 350SDL by shimming up the ALDA and it has caused my tranny to shift hard now. My guess is the tranny on your car is fine, your going to have to adjust the bowden cable, VCV, and check vac at the VCV. I have instructions to fine tune a tranny on a 617, but I'm in search of the info to tune a tranny on an SDL. Thats what you need also.

The owner indicated that he removed the ALDA about a year ago but the tranny symptom has only been over the last month or so.