Transmission issue:

I have a 1998 E350 xlt V10 where about 6 years ago the Ford dealer replaced the original E4OD Trans with a remanufactured F8UZ7 (V000BARM).

Last year it started to make a loud thunk when I would shift out of park to drive / or reverse. Shifts just fine driving. But any time, during the days use, that I shift the auto trans from drive to reverse or from park to drive it makes a loud thunk (foot on brake). U-joints appear rock solid. I searched online and all I could come up with was ‘parking pawl’. So to avoid the thunk (works ‘most’ of the time) I release the parking brake, then start pumping the brakes while I shift from park to drive and this will avoid the loud jarring ‘thunk’. I think I also tried starting it in neutral first too a few times, to try and avoid thunk, and it worked also (I think?). Makes me wonder if there's any external 'electronics' associated with pumping brakes that could be part of problem? I believe I checked the external linkage outside the trans way back and the markings aligned correctly fwiw.

More recently on cold mornings (very mild climate) coming out of driveway the brakes 'might' shudder wildly just rolling to a stop at sub 5mph to end of a very short driveway (only happened 4 times sporadically). With this, after coming to a stop at the stop sign about 100ft away, the trans might slip/stall to engage after letting foot off of brakes to apply gas. After that it doesn’t do it again, neither trans slip nor any brake shudder while driving for rest of day. 161K.

 

How many miles are on the van? if it's over 100K I wouldn't be surprised at anything but it could be motor mounts, trans mount, slop in the diff or axles. Have you put the rearend up in the air to get pressure off of it and checked for slop in the U-Joints or the carrier yolk?

 

Hi Mike - thank you for the suggestions. (161K). I'm not competent enough to rule any of those out but to some degree I could rank their probability (maybe). Since the trans was Ford dealer install good probability trans mounts would have been replaced (but then again 'Ford dealer'), motor mounts would probably give other indications too that I'm not experiencing (still can't rule either out), slop in differential / axels is interesting though (could mess with ABS hall sensor and have caused 'brake shudder' so worth looking into), I did not lift back end when checking U-Joints (duh, should have known better). But I can stop or quell 'thunk' just by playing brake or neutral shift games and sometimes (rare) the 'thunk' doesn't happen at all so that's why I didn't think U-Joints were a main culprit.

 

Well 2 personal experiences here. Had a 95 chevy G10, same thing, clunking when shifting into gear thought is was ujoints lifted up backend and was the diff yolk.
had a 2000 Chevy Savana. Great van but at 170k started unkind and shuddering when applying braks....both rear axles wore out so new inner outer bearing and axles. Van was solid until my 80 year old mother decided to try and start it one day in Florida thought ether would help and started it on fire...oh well least she was ok.

 

You meant to say there was almost zero percent chance that they replaced the trans mount, right? Because they didn't replace it.

To me, that indicates u-joints.

 

With no time to do anything (like all of us) and too many projects I just assumed trans - but you guys have convinced me to look elsewhere. I'll have it up on jacks next weekend for a good going over. Much appreciation for direction & replies.

 

* UPDATE:

Problem(s) was all rear end differential. Replaced all bearings (and axle seals while at it) and she's smooth as silk. Tans is just fine, u-joints all good.

Thanks for pointing me in the right direction. Leaf springs are next (Dayton 43-1157's)