Transmission problem

[salinasboats]

Only had my 1991 420sel 2 months already had an electrical fire and now the transmission went out DUH! Transmission was working great then seemed to drop out of gear at about 35mph.Pulled over and stopped then put her into 3rd and drove about 4miles home .Once close to home stopped put tranny into drive again and this time would only shift into 2nd. Dropped the pan and changed the trans filter and ATF ,old oil was dirty but did not smell burnt .Filter was pretty old but bottom of pan was pretty clean much better than the stuff I have cleaned out of the tranny on my 300e .Put everything back together and went for a test drive still would not shift past 2nd HELP! Any ideas before I pull the last of my hair out(theres not much left!) . Could the electrical fire have damaged a relay (kickdown) or vacumn hose that would stop the tranny shifting? Its been running/shifting fine for a couple of weeks since the fire repairs . Any ideas welcome ,Steve.

[the tenor man]

If you noticed no slipping or flaring of the transmission, try the suggestions below...if you did, it's internal and more than likely, will need to be pulled and repaired.

The shifting on that transmission (722.3?) may be operated by a vacuum modulator valve on the side of the transmission.

Check the vacuum hoses from the modulator valve to the engine to see that they didn't get melted during the heat of your electrical fire.

Also check the wiring to the kick-down solenoid on the transmission.

There may also be a cable that connects from the transmission to the throttle linkage...check that to make sure it hasn't become disconnected.

Hope this helps and that you find your problem...Let us know.

The Tenor Man

[salinasboats]

Thanks for the reply .Wires were all repaired and vacumn hose seems good .Just read anouther post on a 126 tranny repair which involved replacing the B2 piston could this have caused my problem ? Car still has 2nd gear but wont change into 3rd or 4th is this what happens with a B2 piston failure?

[the tenor man]

salinasboats,

Below the accelerator pedal, there is a kick-down switch. It forces the transmission to start in first gear under full accelleration...Check that. It's not unusual for the switch to be stuck in closed (down) position.

There also is a governor located on the side of the transmission...it's internal, but there is an access plate on the side. I've never heard of one being stuck, but I guess there's always a chance. I'm not sure, but my guess is that the transmission would need to come out for that problem.

The B2 piston (as I recall) controls pressure on the band of the transmission. When it fails, you get slipping and flaring...but you'll need to check on this. Search the posts.

The only other thing that I can think of is linkage. Is it possible that the shifter linkage somehow has become unadjusted. I do recall a threaded rod for adjustment from the shifter on the console to the transmission...you may want to check that...

Hope this helps,

The Tenor Man

[salinasboats]

Yesterday I found the problem with my tranny (722.355) not shifting.Cleaned the valve body ,very scary who designs these things ! made no difference so pulled the box out of the car .One of the first things I checked was the B2 piston which looked fine .Next the governor and guess what it was not turning .Turns out a small spring from the rear valve body (I think) found its way into the secondary pump which is driven by the governor shaft.This jammed the gears causing the drive lugs on the end of the pump piston to break off .These locked up the governor which thankfully has a steel rollpin locking the drive gear to the governor shaft this sheared .Hence no drive to the governor so the tranny would not shift ! Now I need to find the parts and put everything back together .But since the box is out I have a rebuild kit and will replace all the friction plates ,seals etc .Will try to post pictures later .steve.