722.6 Transmission Question - PeachParts Mercedes-Benz Forum

loubapache · #1 08-29-2006, 10:10 AM

I read for about 2 hours last night of the search results of all the “good” stuffs about the 722.6 transmissions. While I got educated on the topic, I did not find an exact situation/cause/solution as I experienced yesterday afternoon.

The car is a 1997 E320 with 75,000 miles. Earlier on its life, the transmission ECU (Electronic Control Unit?) was replaced. The fluid is original.

Occasionally I experience a slight vibration when the car downshifts from 2 to 1 (coming to a stop in W setting but happens in S as well). It does not happen often (once a week) and I can live with that.

Yesterday afternoon while driving, the car stuck in 3rd gear and it won’t upshift. I got home and shut it down, and started reading the search results of this particular transmission. There was NO Check Engine light.

This morning, I drove it to work and it shifted perfectly. It went smoothly through all the gears (2->3->4->5) and in 5th gear; the rpm was 2000 at 55 MPH.

So I am a little stumped here. Is this an early sign of trouble for the transmission? What can I do to correct the potential problems? Although there are many potential causes here, is the data plug the most probable cause here?

The car does not have any transmission fluid leak. I am sure a filter/fluid change might help but my gut feeling is that it is not the cause of the problem.

Any advice, insight, and experience is appreciated.

Melcher · #2 08-29-2006, 11:39 AM

Taking it to a shop that can read the adaptation data is key.
My initial pinion of the vibration would be that it is slipping when trying to engage that gear.
If you're a die hard DIY guy, then I would pull the pan and replace the filter. While in there, pull the valve body and clean off the two black magnets on top of the valve body (speed sensors). Higher mileage 722.6s get clutch pack material built up on those speed sensors. It can help a lot.
But as stated in the beginning of this, your adaptation data is key.

Gilly · #3 08-29-2006, 04:15 PM

This wouldn't explain the shudder, for that I'd have the fluid level properly checked (temp readout with computer), but for the sticking in gear it "could" be the range recognition switch. haven't spilled anything into the shifter area have ya? Or sprayed any cleaner into the shifter area?
Gilly

david s poole · #4 08-29-2006, 06:14 PM

i agree with gilly first signs of range recognition switch problems.

sokoloff · #5 08-29-2006, 08:37 PM

And at 75,000 miles it is time to get it serviced.

Len

loubapache · #6 08-29-2006, 08:38 PM

Thank you all for your replies.

No, nothing has been spilled onto the shifter.

I drove it seven times and today and it shifted perfectly each and every time.

I will keep watch it and also read on this range switch.

blackmercedes · #7 08-29-2006, 09:16 PM

Quote:

Originally Posted by loubapache

I will keep watch it and also read on this range switch.

Well, I'd get an SDS hooked up and read the adpatation values and get an idea of what going inside as well, and have a service done while they're there. Have someone with an SDS do it so that the fluid level can be set precisely, it's worth the labour charge.

Also, check for worn shifter bushings, as that can cause the trans to have fits ("range recognition") as it can't "get" the right shifter position. Not uncommon.