craigcully

I just put a rebuilt engine into my 91 f150 2x4 and now my automatic tranny won't shift out of low gear. I had no previous problems with the tranny and all that I touched on the tranny was a new filter and new seals. Any ideas? I would appreciate any feedback. Thanks!

Krickul

How many miles has it been since you changed transmission fluid/ serviced your transmission. When you dropped the pan was fluid burnt or did you notice any material in pan. Your clutches build up a varnish that help them. New transmission fluid is almost like a powerful detergent, it can strip the varnish off the clutches and can cause slipping,or clutch material can stop up valves that would keep you from shifting from first gear. We have many people come into the shop wanting transmission services. We ask them if they have reguraly serviced it or if the are having problems and hope servicing it will help. If its reguraly serviced, the pan is clean and fluid red we service it. If the pan has material/burnt fluid we will not service it even if transmission does not have any problems. Some situations do vary depending on exact circumstances but rarely. We have a lot of people come in who were having problems, mostly slipping, and had it serviced at a different shop, said it worked great for a day and then it got much worse or even completely stopped pulling. If this is your case you will most likely need an overhaul.
Should not be too bad, main reason is to get tranny cleaned from materials, replace clutches and seals. Major hard parts should be fine. You will also want to make sure you have a rebuilt torque converter, your old one will most likely have material in it that will go right into your rebuilt tranny if you put it back on. This is just an assumption, it may or may not be your problem. best bet is to have it towed into a mechanic you trust so they can do a firsthand examination.

craigcully

Thanks Krickul! I'm not for sure how many miles are on the tranny since the last service....judging from the engine I pulled out of it I doubt the tranny has been serviced in all of its 106k miles. I didn't notice anything unusual in the fluid, but others I have talked to have mentioned stuck valves and buildup. I don't have a clue when it comes to trannys, so thanks. Now I just got to find a mechanic I trust.......

ervinj

Before you go through all the overhaul, make sure all of your vaccum lines are hooked up and not CUT. I replaced a engine once and had the same problems you're having and I partially cut the vaccum line to the modulator valve. It would not shift out of 1st by itself but you could manually shift from 1 to 2 to drive just fine and, it could be the valve itself.

ervinj

quaddriver

AOD? did you hook up the TV cable? wont shift without it....