86 SDL with upshifting issues

[930dreamer]

Hello, I've posted before on this problem and had a few questions. MB won't shift out of second gear. 290,000 miles. Nothing I do will change this. The vacuum to the modulator is 12 mg. I've replaced all the vacuum lines. Will placing the vacuum guage between the modulator and hard line and driving give any more data? I serviced the transmission fluid and filter. I drove it four hundred miles last summer and It didn't want to shift into higher gears until warm. Now no upshift out of second gear. No difference with the kick down switch disconnected, bowden cable has the right amount of slack in it. Just wondering if there's something else to look at before going the rebuild route. This is a great site, thanks Shawn.

[Doktor Bert]

As always, check all the simple things first; fluid level, modulator cap, vacuum supply and cable adjustment. If this doesn't fix the problem, it could be a number of things including a problem with the governor. However, I have repaired a number of these units without the need to remove/rebuild the unit.

There are some small, screen filters in the valve body that can become plugged with foreign matter. You miust drain the fluid, remove the pan, drop the valve body and disassemble the halves to gain access to the filter screens.

IIRC, there are 15 bolts that hold the valve body in place. In the rear section of the valve body, there are (2) small screen filters that you can remove and clean with compressed air or brake cleaner.

Consider this a last resort after all other things have been checked. You will need an exploded view to do this...Robert

[930dreamer]

http://www.peachparts.com/shopforum/attachment.php?attachmentid=62540&d=1230605654

Is this the correct valve body?

[Doktor Bert]

Is yours a 722.2 or 722.3 transmission???? I ask because people perform a lot of strange swaps. IIRC, the 722.3 was a 1981-1995 item...Brian Carlton????

[930dreamer]

I'd only be guessing, sorry. I'll have to look at the transmission. Shoud be 722.321 right? Shawn

[compress ignite]

I can't read.

[tbomachines]

Word of warning if you go and take the valve body off...there are a lot of little ball bearings. If you lose any of them you'll have one heck of a time trying to hunt them down on the floor. As the Doktor said, you'll need a diagram for this. Also, have you ever replaced your K1 spring? Not hard to do, probably a good cheap preventative maintenance item if you take off the valve body anyways. If it is broken or stuck for some reason, it may be leading to some of your problems....I know it controls the 2-3 shift in some way shape or form. Perhaps other members could shed some more light on that (I'm still learning!).

[930dreamer]

I"ve searched about the spring kits, one question is would bad springs cause flairing or no shift issues? Part of me wants to remove the valve body and look at the valve screens(filters), the other parts says don't do it.

[leathermang]

The most common cause of stuff like this is varnish build up in the little passages of the valve body...
Try a can of Trans-X first... follow the instructions on the can ( may take two cans for the first treatment depending on the capacity of the trans.. ) but cheap to try and no harm no foul if it does not work... but I have had it work miracles a couple of times... and others have reported success also... ...also do a search in this forum...

[Doktor Bert]

Good advice....

Check/replace the easy/simple things first. As previously stated, the valve body is a nightmare, but it can be done if you are careful and follow the exploded view. I refer to this operation as a last resort after all other methods have failed...Robert

[930dreamer]

Yes the transmission is a 722.321. I took some pictures but the focus is off. Can someone identify this item, fluid is driping from this area also.

[GeoRoadram]

The problem is the plastic switch (kickdown solenoid) under the accelerator pedal. It is stuck closed or broken. You can read my post under General diesel discussion. Good luck!

[Doktor Bert]

What a blessing for you if that is the problem!!!!

[930dreamer]

Per my first post, I've disconnected the kickdown switch and drove, still no upshift! ???????

930

[930dreamer]

If I remove the valve body but don't split it apart, will cleaning it in a ultrasonic machine be good enough?