Hello All,

I have a 93 F 250. The motor is a 7.3 L non-turbo. The trans is a three speed with overdrive. It has the overdrive button on the end of the column shifter.
About every 350 miles it starts shifting hard. The mechanic at my former employer had the following fix. I disconnect the batteries, get under the truck and remove the speed sensor from the top of the pumpkin, wipe it off and re-install. (sometimes the sensor has grime/dirt, other times it just seems like the 90 weight) I hook the batteries back up, reprogram my radio, clear the trip-o-meter and I'm off and running, usually for about 350 miles or so. I have this system down to about 5 minutes now, but still it's a pain. I tried replacing the sensor and also have taken the cover off the pumpkin, cleaned the gears and replaced the oil. All with no success. Any suggestions would be helpful.

Thanks, Jimmy

 

Sounds like you have early symptoms of tranny failure. Does your tranny also have a shudder at say 40 to 60mph with light load and light acceleration? If it does then torque shudder(lockup clutch slippage) has overheated your fluid which overheated seals making them brittle and causing junk to float around.

I had this problem to start, torque shudder. As it progressed I started to have intermittant harsh shifting. Sometimes it woul dbe gone for a few weeks and then it would come back. Harsh shifting is often the computer's attempt to boost pressure to compensate for the converter clutch slippage or other slippage within the tranny. Disconnecting the battery makes the computer forget that it saw a problem so it goes back to normal pressures until it detects slippage again. This is just covering up the problem with computer amnesia.

If either of these problems is yours, you will eventually need a tranny rebuild. The longer you wait the more potential damage you have.

When I had my 94 E4OD gasser rebuilt due to letting the fluid get low while towing, the shop owner told me the pre 95 E4ODs had some weaknesses that made them susceptable to this problem. The torque converter was a weak link which caused overheating and more problems. He said it was especially bad with Diesel versions of the truck.

Sometimes some of the guys can "fix" the problem with just a fluid change. When you drop the pan to check fluid check for color and excess particles in the pan. But most of the time a rebuild is headed your way. When you do rebuild, get the uprated components that Ford installed in later years to correct this problem.

Good Luck,

Jim Henderson

 

Jim,

Thanks for the quick reply. I have not noticed any shutter. It seems to shift perfectly except as described above. Is my next step to have the trans serviced and find out if there is any junk floating around in the pan ? Are there codes that can be read to diagnose the problem ?

Thanks, Jimmy

 

You can skip cleaning the sensor. That's not the problem. Disconnecting the batteries is clearing the code that is making the hard shifts. Reading that code will tell you what's wrong. It's most likely a slip code from a damaged torque converter clutch. It needs a new torque converter (at a minimum) to fix it.

 

A tranny shop can read the codes for you and tell why the computer decided to increase the pressure. In general increasing the pressure is a bandaid to allow you time to get the tranny serviced, so the computer already thinks you have a problem. Some parts stores can read the tranny codes too.

If you are doing it yourself, I would be dropping the pan and inspecting what I see. As mentioned check the fluid for color and smell, the pan for debris and also check the drain pan for debris and any sludge after you dump it.

Problem is that in early stages of failure you may not see any real evidence of problems with the tranny. Sometimes it is just the fluid getting old and all you need is a fluid change. If when you drop the pan everything looks normal you might just change the fluid and see what happens. If there is junk then I would expect you need the services of a good shop.

BTW if you are cheap and don't want to waste fresh fluid after dropping the pan and deciding you need professional help, you could just reuse the old fluid as long as you dumped it in a clean pan and didn't get any dirt in it.

Good Luck,

Jim Henderson

 

You probably have an E4OD transmission. I had one in my 94 that did the same thing. It would shift really hard until I disconnected the battery to reset the ECU. It would then be OK for a while and then go back to hard shifting.

I never had any shudder, the fluid was in good shape, etc, etc. It had about 94000 miles on it. It needed a new transmission or at least torque converter. I never did it though as I just traded it in on another used truck.

Edit: I even changed the fluid completely and it didn't help at all.

Mike

 

I have the same problem. No shudder. It only does it when I turn off the OD for towing. It will continue to shift hard for several day's. then it will be back to normal.

It's been doing this same thing for a while now. The fluid and filter has been changed. It was doing it before the change and does it after the change.

This truck doesn't see a lot of towing.

Fluid has been changed every 30K miles religiously. [30K-60K- 90K]