With 1800 lb empty trailer, after about an hour drive time my torque coverter lock up started to slip, especially going up hill in 3rd gear (surging). Also was slipping in 4th if I added pedal. I have a big cooler, temps did not get above 150. but the situation continued to deteriorate (cancelled trip- returned home). I reciently added a B&M shift plus, only used on setting 1. After unhooking the trailer, all appeared to work fine again- empty truck. So did I blow out some o-rings on the soliniod valves, is the torque coverter on the way out, or an electrical problem with the torque lock. FILP voltage's check ourt within spec, Tach and speed-o work flawless. I dont have a code reader but any sudjestions on one to buy would be aprreciated, as would any ideas as to what the problem may be. The fluid level checked in the middle of all this about 1/4" above the full mark.

 

Did you try shutting off the shift improver? If you buy a code reader make sure it will work pre OBD2. You won't get data off your PCM. Counting the sweeps of a voltmeter will work also. You could install a test light into the lockup circuit to see if the PCM is commanding the convertor to lock and unlock or is the solnoid pack or convertor going away.

 

Unfortunately, the stock converter in the E4OD is not known for it's long life, or durability (and I am assuming the trans is stock except for the shift modifier). Some shift kits can increace the line pressure to the point that the vehicle will break traction durring hard accelleration and soposedly, this is possible without upgrading the seals. So I suspect seals are not to blame.


It also sounds like the pcm is still functioning normally. So here's my theory...


The piston that activates the lockup clutch is prone to developing cracks over time. The cracks releave fluid pressure, and reduce the holding power of the clutch untill it starts to slip. This could explain why the added weight of the trailer was enough to cause slippage. It is also possible that an increace in line pressure could have agrivated the problem by putting more stress on the crack in the piston.

This is just a theory, for now I would keep a close eye on the atf (color in paticular) and try not to drive it if the clutch starts to slip again. Even if the overall temps stayed in the safe range, it's still possible to burn the fluid in, or around the clutch itself. Pulling the fault codes (if any) could also reveal some clues as to what may be going on in there (getting a code reader is also a heck of a lot cheaper than new TC).

I think all vehicles from 92 to 96 used the OBD-1 scan system with OBD-2 used on 96 and up. Although if its possible to use a voltmeter, I would just do that.

 

Thanks Don, the shift improver off or on made no differance once I had the problem.
David- I don't belive my tranny or torque converter are oringinal, the data tag has been painted over silver, and the torque convert is black, almost looks like powder coat. I will pull out my maintenance CD tomorrow and try some troubleshooting. So is this clutch piston replacable portion of the shift electronic pack, upgrade repair kits recommended(is that the .470 or .500 plastic piston that gets repalced with metal one)??? Without the extra weight everthing seamed normal, so I am liking the sounds of your idea, would just as soon fix the problem as monitor it.

For what its worth, since I couldn't use my truck I rented a U-Haul F350 about the same year with a big gasser and an E40D (I dont think it had a torque lock), with a FULL jag of furniture/junk etc, it seamed to shift really smooth, but the power/torque thing wasn't any better than my IDI with improved performance mods, still ended up in second gear a the the top of the hills, just didn't sound as impressive as my headers with 4" pipe.

 

To be honest, I've never actually driven a truck with an E4OD, stock or otherwise. My dad's truck (93 gmc diesel) is equiped 4L80E and what I've noticed is that it seems to be designed to allow the RPMs to drift up slightly durring an upshift, before eventually forcing the engine to synchronize to the next gear. A light throttle upshift can actually take up to a full second. My mom's rav4 takes forever (guessing around two seconds) to shift into overdrive at freeway speeds, but it's technically a car, so I guess it's allowed.The C6 in my truck, on the other hand (pretty sure its stock), will never take more than half a second to shift (quite the kick at full throttle). Kind of sad when you think of what people look for in a new car or truck these days, but I guess a smooth shift is what sells...

Back to reality. The lockup clutch apply piston is in the torque converter itself. So if that's the problem the only real solution is to replace or overhaul the TC. The solenoid that controls the lockup clutch, is-like the rest of the solenoids-in the solenoid body. I'm not sure if there are any upgrades that can be made to the solenoid body, but apearently, the design was improved in later transmissions.

Are you sure that the only change is in the lockup clutch? Have engagement times changed at all? Does shifting gears take any longer?

 

shift kits improving pressure to make the truck break grip?
not to try and hijack the thread but have any of you had problems getting a 7.3 to break grip when accelerating? mine has allways easily been able to break grip even befroe the tranny rebuild and stengtheneing....maybe i got a freak moter or something.

 

"shift kits improving pressure to make the truck break grip?
not to try and hijack the thread but have any of you had problems getting a 7.3 to break grip when accelerating? mine has allways easily been able to break grip even befroe the tranny rebuild and stengtheneing....maybe i got a freak moter or something."

Well of course it's a freak motor, it's an IDI isn't it . What I was refering to was the shift itself happening so quickly, that the tires actually churp everytime the trans pops into the next gear (on hard acceleratiom). At least thats what the manufacturer claims.

 

I did the code check today, and got 11's on both sections of the check, all the sifts and speeds seem be normal with an unloaded truck, so looks like I'm upgradeing to a good RV converter!- HUM so I wonder what else I should be changing when I have it out?? I think I best seek out a local knowlegable transmission guy!

 

Oh well, at least it didn't leave you stranded, or blow the converter alltogether (which can take the rest of the trans with it). At the very least I would suggest an upgraded TC and shift kit. Other upgrades arent all that pricy, but a serious TC usually is. Good luck

 

david85 talking about that hard shift pattern that our trucks are supposed to do. last year when i bought the truck it had a bad trans. so i rebuilt it and put a new converter in. ive noticed that in the morning at first startup when you put it in reverse it takes a little while before it grabs, and when it grabs its not a sudden grab its like it grabs slow. and ive also noticed when you driving it sometimes takes longer for it to shift. 1st to 2nd no prob, 2nd to 3rd takes alittle while to shift depending on how much throttle is given. not at any time does it shift hard.

 

j tate, I've noticed that my C6 can be a little slow to pop into reverse, mainly on cold start. Turns out the idle was close to 500 rpm (when cold), I have since adjusted the cold idle as well as curb idle so that it never drops below about 650, and that seems to have helped. As for the hard upshift, it only happens above about 2400rpm and throttle about 3/4. 1st to second being the most fun, with 2nd to 3d being a little more tame. For more civilised driving, shifting can happen below 1400rpm. I suspect the line pressure is lower, and there is more slip to be taken up in the TC which help to smooth out the shift at those lower speeds.

 

thanks david85 for the responce thats about the same thing mine does, just some times it takes a while for it to shift into 3rd. it depends on how hard im on the throttle.

 

I am leaning towards just replacing my TC with a good RV unit at this time, along with a good flush and fluid /filter change. The truck unloaded seams to work as it always has, the shifts have always been firm, definately crisper than the U-haul I rented. Also my tranny data tag was painted silver, so I think it may have upgraded shift components already. Does this sound like a reasonable course of action to you guy's with transmission experiance! On the otherhand an overhaul kit and even some upgrade parts are not that expensive, but my 30 years of aircraft mechanics hasn't involved many automatic transmissions. With a manual would a overhaul be that difficult. I would hate to swap out a good tranny for a big bucks exchange I don't need. Any thoughts would be appreciated.

 

i rebuilt the tranny in my truck myself, never did it before in my life but was going to give it a try. ive rebuilt quit a few marine velvet drive transmissions in the past and a automatic trans works on the same princables as them. its been over a year since the rebuild and everythings been well so far. the problem i have is my shifting points and thats controled by the vacumn valve on the injector pump, i cant seem to get it adjusted wright. i just wished that when i rebuilt it i would have put a shift improver kit in while i had it apart. i did mine with no probs but i bought me a ford manual just for refrence.

 

If the pan looks clean and there is not a lot stuck to the magnet in the pan it might be worth a try. Was it pushing any fluid out? If you don't have any transmission experience I don't think this is the one to learn on. The Ford manual is quite good and you probably could handle it, but you won't have a good time. Don