I'm at my wits end trying to diagnose an issue I'm having with my E4OD.

For starters
91 f150 302 E4OD 4x4
No codes, No OD light flashing, Fluid color is good, Transmission rebuilt about 25k ago, Torque Converter new with rebuild, trans cooler with electric fan.
Only problem I have had is the front pump seal invert due to bad seal. "How did I know the seal is bad? I worked at the plant that made it. QC is not there strong point"

Under normal driving it works fine shifts good. But twice now when driving some forestry service roads at low speeds for about 30 min it starts slipping in every gear. I get on a paved road for 5 or so minutes and it drives fine. I have a temp gauge installed in the pressure test port and it never read over 150F so I know the transmission as a whole was not hot.

The first time I noticed I stopped and checked fluid. I could smell Clutch/Brake. Second time it was the same. Stopped checked fluid, let truck run and cool what ever was hot. It acts just like when you drive it when the transmission cold.

I would take it back to the Transmission shop that built it but he has retired and sold his shop.

If anyone knows what the ECU is doing different when your Transmission is cold that mite point me in the direction for some more troubleshooting.

 

What about for finishers? Click this & read the caption:


(phone app link)It should always put out at least 2 codes. Read this caption:


(phone app link)Are you saying there's an electric fan ONLY on the trans cooler? Or that the truck has both a trans cooler (factory or aftermarket?) AND an electric fan instead of the factory mechanical fan?So you're saying that got replaced with a good seal? What fluid is in it? Does it have the revised MLPS?


(phone app link)


(phone app link)If it has an E4OD, then the only clutch on the truck that you could smell would be the A/C compressor; and it smells nothing like the brakes. Had you been riding the brakes when you smelled them? Did you check the trans fluid level when you noticed the slipping?So why not take it back to the shop? The new owner might honor the warranty, or at least inspect it for you. But there are other transmission shops you could take it to.It does lots of things differently. But you didn't mention anything about how it runs when it's cold - only when it's at normal temperature.

This caption explains a lot about how the EEC controls the E4OD:


(phone app link)

 

in.Fixed see sig

only gives me 111. I'll check again this Sunday

It still has the factory Mechanical fan. Previous owner installed an extra push fan on a aftermarket cooler up front just for good measure. Fan is controlled by a switch.

Yea Had an FNST seal with under cure on spring lip. This caused the spring to come off and invert. I went with an NGK seal "I think" haven't had a problem with it since I installed it. After that for good measure I changed trans and convert fluid and put Castrol Dex/Merc. I think it still has the pre-revision MLPS. I'll check that tomorrow as well.

First thing I did was check fluid. Level was good, Color was pink.
It wasn't the A/C clutch because the truck never had A/C .
I was going in a slight uphill so I didn't touch the brakes.
Replaced front calipers and hoses not long ago so I dough I have a locked caliper. It just had the smell like burnt clutch. I don't know any better way to describe it.

Sadly the shop is just sitting unused right now. Other shops I've talked to want an arm and a leg to just look at it. Basically they don't want to mess with it.

Ive seen that diagram before good stuff there.

When its cold it slips just like every other truck Ive driven with an E4OD. My dads 95 f250 acts the same way when cold, as well as my uncles 93 F150. They all slip a little when cold. When they warm up it quits.

I remember reading that when the transmission is cold that it doesn't lock the converter. But Ive also read that it lets a clutch slip. Ive not been able to find any thing concrete on what it's doing when it's cold.

 

Did you change all fluid to dexron/ mercon Castrol? Is filter laying in bottom of pan? Is there still a little Mercon v in this 91? Sorry,these are just first questions...if it were mine

 

It was discovered that the main regulator valve on the pump was bypassing. Causing problems with the converter. I just said the heck with it and bought a reman transmission.

 

If you don't mind saying, how much did you pay for a rebuilt E4OD and where are you getting it?

 

Monster Transmission $2100.00 for transmission plus $500.00 core which is refunded when you send your old transmission back. I have access to a shop so I did the removal and install.