Automatic Transmission - squealing noise and slow shifting - 1992 MB 400E

[parnelltk]

I have a 1992 Mercedes 400E with approx. 156K miles. I am the 3rd owner (bought the car with 135K miles) and based on the records that I have, I believe the transmission has not been replaced or rebuilt.

I did drain the transmission, change the filter, and replaced fluid at about 145K miles. I realized later that I did not drain the Torque Converter, so I basically only replaced about 4-5 quarts of fluid out of the system.

Some problems that I notice with the transmission:

* I sometimes (not always) get a loud squealing noise (sounds similar to a drive belt slipping) when the car shifts from 1st to 2nd and when it shifts from 2nd to 3rd. This is most noticeable when the air temperature is high (>85F) and during the first few miles after the car is started cold. I do not notice it much after the car is completely warmed up or when both air temp and car are cold.

* The shift from 1st to 2nd seems to be somewhat slow and not real firm. If you are accelerating rapidly, there is a noticeable drop in the engine RPM during the shift.

* Putting the car into reverse results in a delay of up to 10 seconds or so before reverse engages. If you are on a downhill and shift into reverse, even after waiting for reverse to engage, you need to give it some gas to avoid roll-down.

How about transmission fluid type? When I changed the automatic transmission fluid, I used fluid marked as ATF (Dexron III) based on what I could find in the manual. Is this the appropriate fluid for the Mercedes 1992 400E?

Are the problems that I have described serious in nature? Are there any adjustments or minor repairs that might help the situation?

Thanks for all the help! The forums are really great.

Kim

[parnelltk]

Another thing I have noticed, when I get the squealing noise on shifting from 1st to 2nd and 2nd to 3rd, the next shift comes very quickly, too quickly. Any connection?
Thanks,
Kim

[parnelltk]

How about transmission fluid type? When I changed the automatic transmission fluid, I used fluid marked as ATF (Dexron III) based on what I could find in the manual. Is this the appropriate fluid for the Mercedes 1992 400E?

[david s poole]

based on the time to engage reverse the reverse clutches have worn out and need to be replaced OR the fluid level is way too low.i assume you checked level with engine running?

[parnelltk]

Thanks David. Yes the transmission fluid level shows full with the transmission hot and the engine idling.

What do you think about the occasional squealing noise I hear while shifting? There are other times when it will shift without noise.

Thanks,
Kim

[8092400e]

My 92 400E (165K) did the same chirp between 1st and second and also has the reverse delay. I replaced the belt on an unrelated issue and the chirp stopped. I had related it to the tranny originally but found that the car goes through belts about annually and does the same chirp. SO, now I replace the belt once a year (getting ready to do it tonight). The reverse delay (while annoying) has not gotten any worse in 40K miles, it is softened by a full tranny fluid/filter change and 2 qts of Lucas tranny oil with the change. Better than springing for a rebuilt tranny!

Good luck!

John