W126 Tranny Fixed! - PeachParts Mercedes-Benz Forum

Ed1Sinclair · #1 05-28-2008, 04:21 AM

After some 2-3rd flaring, no fourth gear and loss of forward drive the old 380SE has been reborn. Yes it is possible to repair a Mercedes Benz automatic transmission even without removing it from the car.
First step was head scratching and mild depression at the cost of a replacement unit with a "reconditioned" one.
Then some investigation and net-surfing to assess my options.
Thirdly, lots and lots of research and diagrams (all on the net).
Fourth was budgeting. Parts came to $450 AUD, including $150 for tools.
Finally, a day in the pit under the opened auto box.

As prescribed by various sources (thanks to all!!!) the 2-3 flaring was probably fixed by a replacement K1 kit. Fourth gear is still a mystery but I think was revived by very carefully opening the valve body and cleaning it out. Forward drive was most obviously the B2 piston which had broken into at least six pieces (typical catastrophic B2 piston failure at 220000kms/135000miles). The most tedious part of the operation was removing the old piston seal and metal sleeve. Opening the valve body was risky but I think paid off.

The tranny fluid pan was very clean upon initial inspection so I decided to go ahead with the job since this indicated there was probably nothing else major wrong.

The kick-down (bowden) cable sits at around 1mm play at throttle rest. I did turn the modulator adjustment anti-clockwise 1 turn for softer gear changes.

Now to get some miles on the old girl while fuel is still affordable!

crashone · #2 08-13-2008, 10:42 PM

I'm having some power issues with my SD, how is your car running now?

raymr · #3 08-14-2008, 09:32 AM

I did the K1 kit replacement about a year ago to fix the 2-3 flare. How is your 1-2 shift? Mine has a firm shift thats a jolt at times, and sometimes it does a hotrod-style chirp! If I dial the modulator, then the other shifts are too soft. But I'm leaving well enough alone.

crashone · #4 08-14-2008, 09:47 PM

Mine started slipping when I gave it fuel, like from a stop sign. Now it is like pushing a brick thru mud. I have to manually shift it from 2-3-D to get going. I have changed all filters and checked all fluids. I checked vaccum and it seemed good. Fuses for tranny are good. So I am just wondering if the B2 and/ or K1 kit will fix it. Thanks.

This is in the '83 300SD.

SpecialDelivery · #5 04-09-2012, 09:48 PM

I know these are old threads but for anyone reading, I'm having same issue/conclusions and need to get in there and do a k1 and maybe k2 before I do anything else, now if only could track down that elusive k2 part number! anyone have it POST it please!

JamesDean · #6 04-10-2012, 12:28 AM

Originally I installed the K1 kit as you did, then my B2 failed. I replaced that and my 1-2 shift is barely noticeable at all. I then had 2-3/3-4 flaring issues so I installed this kit:

http://www.bulkpart.com/2/product/722-3vbkits/S68165G.html

After some vacuum adjustment, no more flares. Shifts are on par with my 420SEL. Present but not overly noticeable or jolting.

SpecialDelivery · #7 04-10-2012, 12:47 AM

yup thats the one I've got

Hit Man X · #8 04-10-2012, 10:09 PM

Good to hear you fixed it!

SpecialDelivery · #9 04-11-2012, 12:09 AM

Quote:

Originally Posted by JamesDean

Originally I installed the K1 kit as you did, then my B2 failed. I replaced that and my 1-2 shift is barely noticeable at all. I then had 2-3/3-4 flaring issues so I installed this kit:

Shift correction package 722.3 / 722.4 Gas | Valve body kits | Transmission Parts by Bulkpart

After some vacuum adjustment, no more flares. Shifts are on par with my 420SEL. Present but not overly noticeable or jolting.

does this kit cover the both of k1 and k2 replacement ?

JamesDean · #10 04-11-2012, 02:00 AM

Quote:

Originally Posted by SpecialDelivery

does this kit cover the both of k1 and k2 replacement ?

Yes it did.

Here's my thread on my install:
Superior Shift Kit 300SD

Superior Shift Kit 300SD

Walkenvol · #11 04-11-2012, 04:09 PM

Superior Kit # K722A-G
1.This Shift Correction Package services early and late 722.3 and all 722.4 Mercedes transmissions,1980 to 1990, Gas Models.

This worked on your SD? I need one for a 190D '85

JamesDean · #12 04-11-2012, 09:18 PM

Quote:

Originally Posted by Walkenvol

Superior Kit # K722A-G
1.This Shift Correction Package services early and late 722.3 and all 722.4 Mercedes transmissions,1980 to 1990, Gas Models.

This worked on your SD? I need one for a 190D '85

Shift correction package, 722.3 / 722.4 Diesel | Valve body kits | Transmission Parts by Bulkpart