Torque convertor not locking

[Addicted4]

95 f350 cclb 4x4 7.3 229k miles, after replacing the hpop with a t500 the tuck runs great. No chip, intake or exhaust stock bedsides the 35" tires, 4.10 gears.

So Monday I picked up several axles and no big deal, Tuesday comes around and I have to go pick up a car so I hook up the trailer and off we go. Load up and get headed back and I notice the trans isn't locking up, I had the Od light on cause the way the trailer was loaded so I kept the speed to a minimum, so after I get home I'm letting the truck idle to cool down and I get out and instantly smell burnt clutch. I drop the pan fluid was burnt but still had a reddish tint and not a lot of metal in the pan, I swap filter and new fluid back in. Now the trans shifts perfect and crisp but still no lock up. Oh and no codes either
Also replaced the third brake light bulb and it didn't change anything.

Soleinoid pack or torque convertor?

 

[kip4234]

I had a similar situation happen this summer. I was pulling about 6500 lb boat and trailer on the way back from the Lake about 75 miles into a 300 mile home journey and all of a sudden my convertor unlocks while pulling about 75 mph I have a liquid gauge and it immediately goes form 140 to about 260 in seconds I pull over and you could smell the fluid burnt smell. We had a f150 also towing a waverunner and unhooked it and hooked the heavy boat to the f150 and hooked the waverunner to my diesel and the fluid cooled down and we drove 55 all the way home. I drained pan and pulled the pan no metal at all I flushed all the old fluid out and truck also has a spin on dieselsite filter so I relaced that and the inside filter. now the truck shifts fine but wont lock up just have not had time to replace convertor yet but I think it wont hold anymore.

 

[Addicted4]

Are you sure you lost the torque convertor?

 

[David N]

Wire in a manual lockup switch and see if it will lock then. That will tell you very quick whether its mechanical or the converter is bad.

 

[Addicted4]

Finally set a code p1728, the pcm is calling for lock up but will not lock up. I would hate to put a convertor in it and have something else be the cause or the trans isn't in good enough shape to last. May just have it gone thru at the trans shop but any thoughts and ideas are greatly appreciated

 

[gnxtc2]

Is the 229k on the original trans?

Billy T.
[email protected]

 

[Mark Kovalsky]

Finally set a code p1728, the pcm is calling for lock up but will not lock up. I would hate to put a convertor in it and have something else be the cause or the trans isn't in good enough shape to last. May just have it gone thru at the trans shop but any thoughts and ideas are greatly appreciated

It could be a bad TCC solenoid, a stuck TCC control valve in the pump body, a bad seal on the input shaft, or a bad torque converter. I don't know how to separate those out without a teardown and inspection.

 

[Addicted4]

So talking with a good friend of mine this afternoon we discussed the possiblity that the convertor could not be bad and it could be the clutches. So if I'm driving in overdrive at day 55mph I hold the throttle steady and touch the brake and the rpms come up a few hundred rpm/ release the brake and it drops back down?? Is it possible that it's just blowing thru the 3rd and/or Od clutches?? Just thoughts hell sounds like a trans build is in my future.

The trans is in unknown condition and mileage so hard for me to try and fix this trans with not knowing the history

 

[Mark Kovalsky]

So if I'm driving in overdrive at day 55mph I hold the throttle steady and touch the brake and the rpms come up a few hundred rpm/ release the brake and it drops back down??

That shows that under those conditions the torque converter is locking and unlocking like it should. That doesn't mean it works under higher load conditions.

It is possible that you have a clutch problem. If you do, it usually shows up in the fluid. It will lose it's red color, eventually turning brown or black. It will also have a burnt smell.