Going to work last night, my transmission's torque converter would lock and unlock going down the road at approx 60 mph (flat road, no hills). did this for 3 or 4 minutes, then it quit for the rest of the trip.

fast forward after work, does the same thing coming home. locks and unlocks 8 - 10 times in a few miles, then stays locked.

It did this for a few weeks before I got a rebuild, and was fine for about 300 miles until it did it again this evening. I'm going to take it back in (warrunty), but is there anything I should check out that may be easily fixed? fluid is good, no slipping, still shifts perfectly. Also, I'm looking to gain a bit of knowlege as to what this may cause in case the repair shop tries to feed me a line of bs. thanks!

 

As far as I know, the only things that control the TC's lock/unlock is the TC itself and the computer...

Is this in OD when it happens?? Do you lock/unlock in second and third gears too?

What size tires do you have? What year truck are we talking about?

Mitch

 

There are a few other things. Like all the sensors that the computer looks at. The throttle position sensor, the trans range sensor, the vehicle speed sensor, etc. A problem with any of these can cause it to lock and unlock. So could a worn seal on the pump shaft, or a problem with the TCC solenoid.

 

Well, that's as much as I knew! ha, ha!! You are right, all those sensors have something to do with it as well!

I would think that if he got the trans 'rebuilt', the other things would have been replaced??

I don't know.... I'm talking out of my a$$ on this subject anyway, but figured I'd ask about the other things to get some more info out there to help the folks that know this stuff out a bit better..

Mitch

 

it is a '91 302. stock size 235/75/15 tires. it would do it before the rebuild, but it will only do it in o/d. It seems that after the few minutes of locking and unlocking, it will lock up like normal and stay locked, unless you tap on the brakes, or use the 4 ways, which it gains about 200 rpm, which i think is also normal. i have a 1600 mile move to wv coming up, and dont want a dead truck on the way. It still shifts absolutely perfectly, and has no slip, just the locking and unlocking within a 2 - 3 mile or so range.

 

just an update. Took it out just now, and it did indeed lock and unlock even in 3rd gear. went abuot 1 mile, and it unlocked and stayed that way in 3rd and o/d for another 15 miles. I'm debating if I should just keep driving it as is an let it warm up before running, or take it back into the shop and be withou tthe truck for a week, only for something else to happen when i get it back.

 

If it does it when the trans is cold and goes away when hot, I would bet on a seal problem. If it is anytime, hot or cold, it could be many things. If they replace the convertor with a cheap reman. than it is problably in the convertor.

 

It will not do it after it has warmed up. I went for a drive 3 hours after running it, and it didnt do it. It only seems to do it after its set 8+ hours. Is this something that can be run on for a month or so without any fatal damage?

 

Man, when it comes to a tranny acting up, it might go 5 more feet or 50,000 miles. They will make a liar out of you evertime. With that being said, I believe the worst will be that the lockup clutch in the convertor might quit working only. Hurt the fuel mileage, but still run. The only tranny shop around here that I trust, only uses Ford remans convertors in his E4ODs overhauls. He says the rest are junk (had problems with them).

Just notice its in a 91 model, I would of suggested an Ford reman unit. There were many updates in the mid 90's that are expensive to add. Cheaper to do the reman. with the updates and it has an longer warranty.

 

well i've decided not to put anymore money into a truck i bought for $500.
I have 2 other trucks in WV, so if it makes it up there, then i'll consider putting a new tranny in it.
Should it die on the way from TX - WV, I'll just hook the boat up to the uhaul and leave the truck - so if anyone needs parts and sees an f150 on the side of the road between those places, help yourself.

 

I know that this post is really old, but I figured I'd try to help before you went and replace the entire transmission!

REPLACE YOUR THROTTLE POSITION SENSOR (TPS)!!!!!!!!!!!!!!!!!!!

That is your problem I am 99.9997% sure!

I bet it does it even more with the cruise control on right? Or constant light throttle, like highway cruising?

Yeah, go ahead and change the TPS.....it's not expensive and I'm sure it will fix your problem! + it may increase your mileage a bit, it worked on mine!

Vince