Transmission mission. Can we fix it? - PeachParts Mercedes-Benz Forum

troytrinkle · #1 09-16-2007, 08:14 PM

Hey Transmission Gurus,

I've got one for you. I recently bought a 1985 190d with 2.2 engine mated to a 722.403 transmission. It had shifting problems when I bought it, and it was cheap. How could I go wrong? Transmission are just machines. We fix machines everyday.

All of the information I'll share with you has been gathered during the last few weeks as I've educated myself through forum articles and some aftermarket service litature. I humbly present myself as a novice with a stubborn need to fix the machine.

The problem presented itself as flaring between 3-4. The car would drive and shift well until it shifted to 4th gear then nothing but a racing engine. With the guidance from articles presented by Steve Brotherton and Diesel Dan, I have narrowed it down.

Here's what I know:

1. I have great vacuum and no leaks.

2. I have no play in my kick down cable and it doesn't hang.

3. I have good modulator pressure.

(I think Dan had more room under his w123 shown in his Wiki article. Testing the transmission pressure of my 201 model was a trick. I had to drop the rear mount to get at the test port. I also found an alternative to using a banjo bolt for tapping the test ports. I used a 1/4" nylon hose barb. I just threaded it and stuck it in. However, the banjo bolt would have worked much better, but parts options on a Sunday afternoon is limited. Lowe's was my only choice.)

I had 2.8 bars of pressure when I cranked the modulator all the way in. Which was only an increase .2 bar through full adjustment. However, 2.8 is what my data sheet called for.

During the road test I felt the car kick into 4th gear. This was very encouraging, but it would slip when ever I stepped on the throttle. However, when I reconnected the vacuum to the modulator valve, I lost 4th gear altogether. I flarred from 3rd gear.

The ATSG book has a remedy, but their info isn't sound enough for me. I've found thier manual useful, but a little messy. However, this is what they say to do when your tranny slips during 3-4 shift:
1. Adjust the modulator. (done that)
2. Change the shift valve housing. (which one and what housing)
3. Recondition the K2 plates. (I might pass on that)

Ok. So there's the skinny. What do I do now?

rs899 · #2 09-17-2007, 07:09 AM

When ATSG says "change the shift valve housing" I would interpret that as something in the valve body. But who knows? They seem to write manuals like Alan Greenspan wrote market predictions.

dawsonj3 · #3 09-17-2007, 07:54 AM

How high is the vacuum going to the transmission? Try reducing it to 12 mm or even 10mm and see if the flaring problem goes away.

patbob · #4 09-18-2007, 11:43 AM

Quote:

Originally Posted by troytrinkle

The ATSG book has a remedy, but their info isn't sound enough for me. I've found thier manual useful, but a little messy. However, this is what they say to do when your tranny slips during 3-4 shift:
1. Adjust the modulator. (done that)
2. Change the shift valve housing. (which one and what housing)
3. Recondition the K2 plates. (I might pass on that)

I checked my booklet last night for my transmission on the assumption it probably has the same troubleshooting steps, and it was pretty clear. It said "exchange the valve body" for step 2, and "recondition the K2 clutch pack" for step 3.

I don't have the link today, but you can buy a valve body, cost was ~$300 last time I looked for my transmission (722.3(15?)). Is exchanging the valve body a DIY project? Well, you've got the manual, so you can judge for yourself.

chuni959 · #5 11-28-2007, 11:34 PM

When i hear the words valve body and DIY in the same sentance, it reminds me of the 500e owners who wanted the 1st gear start. One way to do it was to modify the valve body, and people generally shuddered at the idea of removing the valve body. But then again, we all know what pompous *******s those 124.036 owners can be =P

dunl · #6 11-29-2007, 11:07 PM

Don't know about yours, but the valve body on my w116 was an in and out 15 minute procedure, including draining the pan.

mbdoc · #7 11-30-2007, 08:23 AM

Since that is a common problem on all 722.4 & 722.3 transmissions....you need to completely disassemble that trans & repair the problem on the K2 clutch pack.

chuni959 · #8 12-17-2007, 12:49 AM

is the k2 the pack located directly behind the front pump?

hawthorne90250 · #9 12-17-2007, 01:36 AM

Quote:

Originally Posted by chuni959

is the k2 the pack located directly behind the front pump?

This Might Help.

pawoSD · #10 12-17-2007, 01:44 AM

Any way to get those images a little bigger/higher res?....they're ok....but bigger is always nice.

hawthorne90250 · #11 12-17-2007, 02:01 AM

Quote:

Originally Posted by pawoSD

Any way to get those images a little bigger/higher res?....they're ok....but bigger is always nice.

I am not sure, i switched to Linux Ubuntu a few months ago and am still working out the kinks. if you download the catalog at http://www.transmissionparts.com/ (88mb)
the pictures are large and very clear.Maybe some of the Admin might be able to do it better and post them as a sticky.

pawoSD · #12 12-17-2007, 02:12 AM

I downloaded the catalog. Thanks!