Hi guys, I'm at my wits end with this one and looking for any and all ideas about a solution to this little dillema other than drive the thing into a tree and collect insurance.

I've got a '90 F150 4x4 that is leaking trans fluid from the t-case, between the t-case and the transmission. The t-case is a BW1345 and the trans is a M5OD. Here is what I have done so far:

- replaced the tranny with a new M5OD (the old one was ready to retire). The tranny is not leaking anything and is shifting quite well, although it is a little bit noisy in 1/3/5 gears. I don't think this is all that uncommon though. I've kept a close eye on the fluid in this due to what it cost me.

- replaced input shaft seal on t-case - still leaks

- replaced input shaft seal on t-case with kwik-sleeve - still leaks

- took t-case to tranny shop where I got my transmission. They dissassembled, cleaned, pressure tested, reassembled with new seals and bearings - still leaks

- took t-case back to tranny shop and had freeze plug inside input shaft removed and resealed, new freeze plug just outside the mounting area replaced (just for good measure) - still leaks

- removed t-case and ran the truck on jacks in 5th gear at about 1500 RPM's to check for anything obviously out of round on the output shaft of the transmission (tranny output shaft seal is not leaking) - didn't see anything noticeable

And here I am with another spot in my driveway. It dumps about 1/2 quart in 40-50 miles through the drain hole between the tranny and t-case, and leaks only when driven. I feel like something has to be bent in there and is opening the seal somehow when driven, but I certainly cannot find it. There are no burrs or anything on the mating surfaces of the tranny or t-case, and it is mounted flush and torqued properly.

I replaced the gasket between the tranny and t-case the first time, but have not replaced it since the second removal. The guys at the Ford dealership here in town told me that this gasket is more to keep things out than keep things in (like if you back your truck down a boat ramp and submerge it water). Could it be that a lack of a gasket causes a vacuum and pulls the fluid out (I'm really reaching here....)

Does anyone have any ideas at all? I'm about out...

Thanks so much for your help.

 

I'm not very familiar with transfer cases, but I'm curious to know when they did this, did they check to see that the input shaft was w/in tolerance and straight? It's nice to assume that they did, but sometimes these specialty shops will only do the work you ask them to do. If you don't request it they won't do it, even if it seems like something that should be a no brainer thing to check.

I think you may be right that the shaft may be slightly bent or bowed- if you've had all this work done and it's still leaking, that sounds like a reasonable explanation.

Really the only advice I can offer is to either cut your losses and buy another transfer case, or drop it again and have the input shaft checked.

Good luck- keep us posted.

 

Thanks for the reply. I pulled the case back down immediately after driving it and could clearly see that the fluid was leaking from between the shaft and the inner diameter of the input seal. The shaft has to be untrue.

So I took your advice and bought another Tcase. Found one on Craigslist last weekend. Popped it in and for $50 + 20 minutes to pull it 10 mintues of driving and about 20 minutes to put it into mine I'm back in business with no leaks. I didn't realize there were so many used ones so readily available out there. For that matter, I can hardly buy a seal kit for the thing for $50! I'll remember this in the future.

Thanks again for your input.