1989 B-150 AOD transmission problem

Hi Guys, I had this transmission fully rebuilt 2 years ago, ($2000.00} OUCH, I noticed yesterday that it shifts very smooth, through all gears, after getting into AOD if I let my foot off the accelarator it shifts back down to 3rd, If I accelerate it shifts back into AOD, fluid level is full and looks and smells good, any ideas??????????? PS Thanks this is a great Forum

after getting into AOD if I let my foot off the accelerator it shifts back down to 3rd, If I accelerate it shifts back into AOD

That's just the opposite of how it is supposed to work. How are you determining the up and down shift points? Are you watching a tachometer or just going by feel?

Im going by feel, it is obvious when it shifts up and down, Thanks

Im going by feel, it is obvious when it shifts up and down, Thanks

Has it always done this, or did this just start happening recently?

When taking your foot off the gas in OD, the converter should unlock, but the trans remains in OD. It locks up again when you press the gas again (unless you give it lots of gas, of course). All the Chrysler overdrive transmissions I have driven do this.

So, if your' has always done this, are you possibly mistaking the unlocking for a downshift?

If this is something new, there may be a stuck valve on the valve body. This can happen if a tiny piece of debris has come loose and become wedged in there. I would suggest dropping the transmission pan, cleaning it out, changing the filter, reinstalling it and add new fluid. Do not just get a transmission 'flush'. These do nothing to clean up the pan.

Some black sediment debris in the pan is normal. Lots of sparkly metal debris is not.

Look for a very thin magnet stuck to the inside bottom of the pan. This captures metallic debris. Magnets are placed in all transmissions from the factory, but for some reason, transmission shops and mechanics like to throw them away!

If the magnet is missing, install a new one.

If your magnet is missing, that might explain the debris in the valve body.

After a fluid and filter change, just drive the truck and the debris may eventually work its way out and solve your problem.

If not, then disassemble and clean the valve body. But the valve body is quite complex and one misplaced tiny check ball or component can really mess it up, so its best to leave the valve body for a professional.

BTW this transmission should be an A500. The AOD is actually an older Ford transmission. :)

Thanks for the reply Magicrat, I drive this truck daily, and never noticed it before, it could be that I just never payed attention to it before, but I dont think so, I also noticed now that it is using gas more, that would be because of being in 3rd gear alot, It usually shifts into Od at about 45 mph, and stays in od until I stopped or was climbing a hill. now even above 50 as soon as I let off the accelerator it shifts down to 3rd, and when I accelerate it shifts back to OD. Am I imagining things???? PS I will also post a seperate post on a problem that happened a month ago and this forum saved me a great deal of money, Thanks for all of you advice guys, Ron