If I had any! My '95 F-150 4X4 trailer towing w/ 5.0L.

I replaced the 4R70W with a rebuild at 198K. Not long, maybe 3 months the OD light starts flashing and the only code shows excessive slip of the torque converter. The rebuild shop advises Trans Guard additive and two of those little tubes makes it operate like a new unit. After another couple of months, same thing so they send me another TC. BTW, with the tranny switch I used Mercon V . Second TC installed I use Mobil 1 ATF and on my merry way I go.

2 months later, same issue. In goes 2 tubes of Trans Guard and all is well for 3 weeks then same issue, excessive slip and limp home mode!

I am tapped out. I sure wish that I would have sank all the $'s I'm out now into the original transmission but that is spilt milk.

I am guessing the TC clutch surface has developed a glaze and right now I am looking for a shade tree mechanic fix to add something to the fluid that could break the glaze. I know I can't go too wild because of the bonding of band surfaces could be compromised.

Any ideas? Would a short run of Toluol, acetone, 111 Trichloroethane, Panda ****, anything gonna help this every day Joe fix his old love??

The preventive maintenance on this truck is done. No vacuum leaks, all engine control sensors, solenoids, etc are new. New off road Y-Pipe.
This truck purrs! I change the Mobile 1 engine oil every 10K and it doesn't use a drop, other than this damn TC issue !!!!!

As usual, I cast myself onto the mercies of the community for any thoughts??

 

You posted this in the 80-86 forum you should post this in the forum for your year of truck

 

Or the transmission subforum.

 

You posted in the wrong forum, this is 1980/86 F100/150 and larger series trucks.

You want the 1987/96 F150 and larger series truck forum.

Note to members: OP also posted in the 1973/79 forum.

 

You posted in the wrong forum, but I have something you can try. Go to the store and buy some of this stuff called "Lucas Tranny Fix". It may be the same thing you have already poured into the trans before. This stuff does work for your problem. But it's not going to fix something that is wore out.

I used it on my daughter's 94 Bonneville. It had the same problem, we called the car "Lurch" because as you would pull a hill it would start lurching. After awhile it got so bad it would drop out of overdrive and only run in 3rd gear. I did a bunch of research on the web, it seems GM started using a solenoid valve in the trans that is pulse width modulated to vary the pressure of the tranny. The plunger in this solenoid is vibrating back and forth all the time in a aluminum bore of the valve body. Over time the bore wears, and the pressure in the trans drops, so the clutches in the torque convertor do not have the pressure they once had and they start slipping. Just like your truck, the computer monitors the amount of slip in the trans, if it's too high it recognizes this and does something about it.

I said all the above to tell you the snake oil will fix/hide the problem for awhile, but you need to find out what the real fix is. If the trans is under warranty, figure out what the problem is, do some research on the web. I bet you are not the only one with a 4r70w with this problem.

It seems at least GM never learns, (probably Ford also) I have a 1999 Tahoe that acts up once in awhile. In hot weather with a load, I will come to a stop light and then when I take off it will bang and shift hard. Again I did some research on the web, it has a 4l60E trans. They got the great idea to make the torque convertor clutches slip on purpose. Using it as a "virtual gear" when the engine needa a little help, instead of pulling out of lock-up mode, they just lessen the pressure and let it slip a little bit to help the engine out. Well you can tell this is not going to make the torque convertor clutches last long, and also again, they have a solenoid valve that vibrates in the aluminum valve body and the bore wears out in the valve body. Same thing, same scenario. They do make a kit with the special tools to repair the valve body.

 

I could move this thread if the OP wants me to but he got a decent, constructive answer (eventually) and it's not really hurting anything.... I know virtually zero about automatic transmissions of *any* generation and appreciate the information, they are a black box to me that do a job. Maybe @Mark Kovalsky can add more.

But yeah, the 4R70 is the next generation.

 

IMO: Since the OP posted in the 1973/79 & 1980/86 forums, he wouldn't get the help he needs in either since he has a 1995.

 

My SWAG is that you have worn or damaged seals on the input shaft. This reduces the pressure to hold the torque converter clutch, allowing slippage. You say this is the second torque converter in this trans, and that they both did it. I think the root cause is not the torque converter, but a problem in the trans, such as the seals I mentioned.