I have a friend that I am diagnosing this problem for and I will be doing the repair, if he decides to do it. He drives a 2002 SuperCrew with 5.4L and 4R100 trans, it has about 90K miles on it. The problem is if the truck sits for several days to a week, usually when he is out of town on business, when he comes back and starts it up, it won't engage into gear until he steps on the gas and runs the rpms up a bit, then it bangs into gear somewhat and goes on down the road. After that, it works as normal. If he is driving it every day, then this does not occur. The only thing I can think of is converter drainback, what do you guys think? What all do I replace to fix this condition? TIA for any help.

 

Hate to sound obvious, but is the ATF level correct? I had similar experiences with some fleet cars (Aerostars); same engine and transmission options in each car. Two of these cars would exhibit this problem until we put in more fluid than was indicated as "normal" on the dip stick. Also, if we put in a little more than that, the fluid would boil out of the dip stick after it got hot, so there is a "correct" level.

If the ATF level is where it should be, then it seems that even if the fluid completely drained out while sitting for a long time, running the pump for just a few seconds should have filled it back up. So I'm wondering if there might be a problem with the pump or a clogged filter. Does it make a difference if you let it idle for a longer time before trying to shift?

 

https://www.ford-trucks.com/forums/6...-on-4r100.html Have a read here.

 

That was the first thing I asked and he tells me the fluid level is good, I may have to check it myself, tho.

LazyK, thanks for finding that. I swear, I searched on "drainback" and "leakdown" and did not find that one, maybe I did not go far enough thru the pages. One thing confuses me about that, tho, it gives the only possible problem as the check ball in the rear cooler line - what is the anti-drainback valve in the pump for, then?

I did tell him he needs to check the fluid level before he starts it up after it has sat for a week in the airport parking lot but he keeps forgetting. You know, he gets off the plane, he gets his bags, he's tired and he wants to go home, so he doesn't think about it until after it won't go into gear. My advise so far has been ignore it since it's not bad enough to happen every day. I am glad to hear that my idea of checking fluid level after it has sat is how Ford wants you to check this.

 

No problem on the search.
There are some outstanding trans. experts here, Mark Kovalsky, jk080 and others who may be able to shed more light.
Good luck with it.

 

I don't have anything to add.