Transmission: won't start off in drive when warm

I've got a '97 explorer 4.0 with 150,000 miles.
Lately, once it warms up, if I change from drive for whatever reason, when I put it back in drive, it doesn't engage. If I put it in low, it will engage and then I can move it to drive and everything is fine until I take it out of drive again. It never happens when it's cold. Sometimes when it's really warm, I have to put it in L1 to get it engaged, then on to drive and all is well.

It shifts great. No clunks or noises. Except for this, it seems fine. I changed the fluid hoping it would help and it seemed to a little (seems like it has to be warmer than before before it happens). The old fluid looked and smelled good. Not alot of gunk on the magnet and nothing in the pan except fluid.

Might a complete flush help or is this the beginning of the end?

Thanks.

What transmission do you have?

Do you have the correct specified transmission fluid in your trans?

Don't flush the trans, usually high milage transmissions that haven't been flushed on a regular basis. Might have some debris break loose when flushed and block something internally and fry it.

That is good mileage for trans, so a rebuild is probably in order.

Dean

sounds like you have a bad module...pull hose off tranny module and see if theres fluid in the hose....if there is tranny module bad.
good luck...

Thanks for the replies. I'll check the module this weekend.

On my 1997 F-150 with E40D I replaced the solenoid pack in the transmisssion.
They aren't very hard to change. Pull the pan and unbolt it takes torx bits. Bolt the new unit in and plug it in. I'm not a transmission man but I also cleaned the valve body but it was clean. Don't try this without a manual and on a lift not jackstands. I used a friends lift at night.
You will need fluid,gasket and filter,plus the solenoid valve pack. Replace all of them.