91 Aerostar Transmission A4LD Slow / No Upshift

[yfh8sit]

I have a 91 Aerostar with 204,000 miles on it. The van is a trooper, but has just recently started with a no upshift from 1st to 2nd when trans is a first start cold situation. Outside air temp may also have something to do with it since we are in 30F degree weather now. The van shifts gear positions smoothly from reverse to forward, with no abnormal clunks or bangs. On cold startup, I put the van in "OD" and start off, and it holds in first gear and will not upshift, even if I let off the accellerator. I can manually select second gear on the shifter and then it will upshift. I can then shift back to "Drive" or "OD" and the transmission will shift as normal all the way through the remaining gears. I checked the fluid and it was dark and smelled burnt, so I immediately replaced the pan filter and fluid. (the 4qt change of fluid, not the 10qt including the TC) I could see no other souces for a leak of fluid. The shifting feels smoother, but the no upshift concern is still there on cold startup. After the transmission has warmed up (Approx 3/4 of a mile) the transmission shifts as normal in all positions, and the problem goes away. I feel no slipping in it, and no hesitations shifting between gears after it has warmed up. I'm a fairly decent mechanic, and have done alot of work on my own cars, from oil changes to engine rebuilds, but I'll be the first to admit I'm not that comfortable with a complete teardown and rebuild of a transmission. My specialty is OBD, accessories, and heavy engine work. Any constructive suggestions would be appreciated

Thanks

[sgtaerostar]

Your transmission problems are most likely caused by a bad governor. I have replaced several of them to correct the exact symptoms you are describing. Cheap and easy job. The last governor I bought from the Ford dealer cost me $30. For someone who builds engines, this will be an easy task for you. I've even went to a friend's house and replaced it in his driveway in 30 minutes!

Remove trans tailshaft housing (support trans, remove: rear mount, speedo cable, driveshaft, housing bolts)

Unbolt governor and bolt new one on. Dip it in trans fluid before installing - very important

Also, don't try to rebuild/clean the old one. I've tried without success. For $30, put a new one on.

Good luck.