transmission leaking into transfer case

[zerokohl]

I have a 2000 limited 5.0 and I went to change my tranfer case fluid and took out the FILL plug and out poured about 2 qt (before I plugged the hole back up) and I don't know why it would come out the fill plug. My only guess is that there is a seal that broke and is pouring all the transmission fluid into the transfer case. Anyone know possible reasons. I've been looking through but didn't find anything so I figure I'd ask. Thanks for any help.

Maybe it is the same thing causing the vibrations when shifting into o/d though it doesn't happen every time but enough for it to bother me.

 

[imp]

A cavity exists between the transmission housing and the transfer case, in which the 2 shafts are coupled together. Two seals are involved; the usual transmission rear seal keeps fluid IN the trans., the transfer case input shaft seal keeps fluid IN the transfer case.

Some units have a small vent hole, to relieve leakage should EITHER seal fail. If the vent hole becomes plugged, since fluid may pass a sibgle-lipped seal EASILY in the reverse direction, a failed transmission seal may allow trans. fluid to enter the transfer case PAST it's input shaft seal.

The trans. output shaft seal likely will need to be replaced, necessitating removal of the transfer case. At that point it would be folly to not replace BOTH seals. imp

 

[zerokohl]

Thanks imp wasn't really hoping I would have to do that but was expecting to have to. Guess i better get pricing everything cause I know its not going to be cheap just getting all the fluids. Have you seen any threads on the transfer case removal if not I could look through the repair manual but it is so vague on the pics. Thanks again imp

 

[drdoom]

Is your transmission low?

Also, I don't know how the 5 liter is, but on the 4 liter, the transmission extension housing is wet, it is a lubed area. There is no "rear seal" on a 4wd transmission...when the transfer case is pulled, you could tip the transmission up and all the fluid will run right out the back.

 

[zerokohl]

Last I checked it wasn't low but I think that when the dealership flushed the tranny they didn't check the transfer case to flush that and both of them got refilled when they refilled the tranny after the flush. It had gone it to the shop to fix the shuddering when shifting into o/d. But not sure if the whole cause was because of the seal that imp was talking about being broken and the chain in the transfer case floating. Haven't had a chance to get into it yet. Hopefully Wednesday I will.

 

[imp]

Is your transmission low?

Also, I don't know how the 5 liter is, but on the 4 liter, the transmission extension housing is wet, it is a lubed area. There is no "rear seal" on a 4wd transmission...when the transfer case is pulled, you could tip the transmission up and all the fluid will run right out the back.

Begging your pardon, but my '96 with 4.0L auto trans 4X4 did not have the "wet" cavity between trans and transfer case. Each unit had it's own seal. When I pulled the transfer case out, the cavity was dry. Reason for opening up the damn thing was transmission failure.

Perhaps two different designs were used concurrently? imp

 

[drdoom]

Never heard of that...so your saying your valve body has no provision to lubricate the extension housing i.e. extension housing lube orifice?

 

[KPT]

on the 4 liter, the transmission extension housing is wet, it is a lubed area. There is no "rear seal" on a 4wd transmission...when the transfer case is pulled, you could tip the transmission up and all the fluid will run right out the back.

My only experience is with the M5OD but this is not the case.

You can see the drain imp is talking about in a pic from my rebuild thread:

 

[drdoom]

OP, check your transmission vent tube for blockage, and make sure your transmission is not overfilled.

 

[drdoom]

OK, I see the drain on the M5...on an R55, there is a weep hole, but not to atmosphere, it just drains back to the pan.

 

[wollimann]

TC permanantly overfilled

Hi to all Explorer specialitst!

Unfortunately i have exactly the same problem. Every 3 days there is missing 1 liter of tranny fluid, which i have to drain out of the TC.
(Tranny 5R55E (95-97) with 2 sensors an speedo at TC, V6 SOHC)
The tranny is not overfilled and the vent tube should be free.

There must be a unnormal pressure to cause the tranny fluid entering the TC.
After my TC rebuild everything was fine (6 month ago), now oil is leaking out of the lower TC front seal and the vent tube above of the TC.

I am not firm in diagnosting this problem, but for my understanding there should be a seal at the end of the tranny. Could someone confirm this?
What's the best approch now?

Thanks in advance

Wolfgang