I have 1990 E-350 diesel cutaway Born Free Motor Home used for business showroom. I am having a weird problem only after driving 30-50 miles or more (easy to do in Atlanta).

This has happened twice in the last week. I have driven to an appointment 30+ miles and stayed at the appointment for about an hour. On the way back (both times) after being on the interstate and slowing down to get off, the trannie would not downshift automatically. You could bring it thru the gears manually and the 2-3 shift is very firm. Last time I topped of the fluid thinking it might jsut be a bit low. It happened that I topped it off a couple of hours after parking it. Today wehn it happened, I let it sit and did not add fluid after it happened. Waited a couple of hours then went and test drove. It was fine again.

What component can be affected (presumably by heat) from driving for a period and affect the shifting. Could it be the FIPL? Never heard of one being sproadically bad - only either working or not... This has only just started as I have taken recent trips to Alabama and south Georgia. It is also warmer now than when I took the recent road trips...temps in the 60's.

 

it could be the converter.mine did the same and then some.mine turned out to be a bad computer unit.the Torqe converter could be my geuss.if the fluid is low it will not lock up on the downshift unless done manualy.thats why they use so much fluid is couse thats a big converter and fluid is how it locks and unlocks.the valve body could be going south too.if thats bad it wont create enough fluit presser and cause the converter to free wheel not enough fluid presser on the clutch disck.the clutch disks aren't very big and there is only 4 of them.the e4od is not the best of trannys to have backing a diesel.