1984 300td transmission issue - PeachParts Mercedes-Benz Forum

turbozeke418 · #1 04-12-2017, 01:42 PM

I've been attempting to figure out my transmission issues on my car for a while. When you shift into drive...you hear it but about 1 secone later, it finally engages. It has the same type of symptom when driving and you come to a stop. When you hit the accelerator it rubs up to about 1500 RPM and then it engages. It's almost as if the trans is told what to do and then thinks for a second and actually does it. Here is the link for a recording I made last night to try to explain it.

https://youtu.be/Oh30HQMevms
Not sure if you can hear what's going on if you turn it up. I put annotations on the video when I shift in drive and neutral. You can also see the car lower and raise with each movement.

It has 292k miles and the previous owner had the trans rebuilt 20k miles ago (2 years ago). Someone who knows a lot about these transmissions said it is most likely the valve body.

turbozeke418 · #2 04-13-2017, 09:31 PM

anyone??? please?

tyl604 · #3 04-15-2017, 06:18 PM

This is just a wild guess but I wonder if you need new shifter bushings. Maybe it does not know exactly what gear it is supposed to be in.

barry12345 · #4 04-15-2017, 09:49 PM

Sounds like a substantial delay in initial pressure buildup once a function is selected. I know almost nothing about automatic transmissions but a really old and contaminated transmission filter might do this. If it does the same in reverse I might try it. A delay in getting reverse gear alone has been an indication these transmissions are getting worn.

It has been a long time since I dealt with the transmission fluid level. I think it fair to say these particular transmission are more sensitive to the fluid level than many. So read how to check the transmission level properly and check it.

Also if the internal seals are drying out with siting around a can of transmission treatment can expand them back. It takes some milage and time for the conditioner to do this. When they get old and worn or shrunk. The conditioner really can restore them to provide a better sealing function. Also it can clean the varnish out in the valve body that can in itself cause sticking.

turbozeke418 · #5 04-15-2017, 10:22 PM

Trans filter is new, new fluid to the correct level and no delay going into reverse

Junkman · #6 04-15-2017, 11:18 PM

I posted a link to some trans manuals today. Have a look at the diagnostic sections.

ROLLGUY · #7 04-16-2017, 03:42 PM

I am no transmission expert, but have recently learned a lot about the B2 piston. It sounds to me like that may be the culprit. I am not sure if the modulator pressure affects the overall pressure in the trans, but if so, increasing (clockwise) the modulator pressure might help.

Dmitry at Pelican Parts · #8 04-17-2017, 04:55 PM

Like another member stated, it could be the shifter bushings. If so, take a look at the link below for the DIY fix!

Mercedes-Benz W123 Shifter Bushing Replacement | W123 (1977-1985) | Pelican Parts DIY Maintenance Article

-Dmitry

turbozeke418 · #9 05-03-2017, 12:14 AM

I just replaced the valve body and that solved the issue!