Output shaft seal leaking into transfer case

[Mbrooks420]

Was checking my axles this morning, and found two quarts of fluid I bought for my t case. I opened the fill port, and fluid came out. It'll probably be a week or two before I can get the seal swapped out, should I fully drain the t case, and refill to get the Mercon V out of there?

On the plus side the fluid that came out looked great. .

 

[CDW6212R]

Interesting. Yes I'd say drain and replace the TC fluid. Is that the original AWD TC, not a BW4406 4WD?

 

[Mbrooks420]

Yes, all factory running gear. On level ground an extra half quart came out. Looked very new. I wonder if it could have been overfilled by tipping to one side when last changed. It is currently filled to the proper level with the correct fluid.

Also changed the majority of the fluid in both the axles. I might pull the top plug in a week and see if it took on any more fluid.

 

[imp]

@Mbrooks420
It has been mentioned that not all Transmissions with a T-case attached use an output shaft seal. My 04 surely does. Point is, a leaking transmission output shaft seal will allow passage of it's fluid into the T-case, due to two facts: the slope of the drivetrain, and the T-case input seal being only able to CONTAIN fluid, not EXCLUDE it. Unless the T-case input seal has double opposing lips, it will allow entry of fluid to the T-case. imp

 

[Mbrooks420]

I understand the method on how it potentially leaked into the transfer case, I'm just not 100% positive this is what's happening. I'll wait and see if the level increases. I have no desire to yank the t case unless there is a reason.

 

[imp]

I understand the method on how it potentially leaked into the transfer case, I'm just not 100% positive this is what's happening. I'll wait and see if the level increases. I have no desire to yank the t case unless there is a reason.

@Mbrooks420
Main thing is that you understand that possibility. The interface between Transmission to T-Case Adaptor is gasketed, in those I have observed. That fact prevents leakage diagnosis based on fluid appearing at the T-Case-Adaptor Flange junction, instead of increased fluid level in the T-Case. Yet, observers here on the forum claim many have no gasket. That's hard to imagine as an OEM provision. Some repairmen may have failed to replace the gasket, believing those two fluid seal visible were adequate. OTOH, I have seen Adaptor housings having a tiny hole drilled in their bottom, perhaps 1/16-inch in diameter, obviously aimed at allowing Transmission seal leakage to become visible. My 2004 has no such hole. It may even be possible that given "farming out" supply of such Adaptors, one supplier's philosophy on this imponderable was to supply with a "weep" hole, while another's did not, regardless of what Ford's spec may have contained. imp

 

[transman304]

Does your transmission fluid level show that you have lost fluid?

 

[Mbrooks420]

It doesn't appear to have lost fluid, but it was changed when the t-case was. I doubt you could accurately tell if a pint was missing out of the transmission. Way too many variables.

 

[CDW6212R]

I think you are in fine shape to drive it and check the TC level in a week as you planned. A extra half quart is surely possible to put in if the vehicle is un-level. If it is coming from the trans, it's not an emergency either.

The rear trans seal will sometimes let a little fluid past, when parked on a good incline. My 95 Crown Vic(same 4R70W) has 2-3 times left a small puddle of ATF when parked uphill on a steep driveway. If you had that kind of slight leak, it would not be noticeable on the dipstick, and would take a long time to add much to the TC.

 

[Mbrooks420]

I have had my Mounty on such a steep incline my rear bumper was dragging in the ground. Its been a year since birth were changed, so a half a pint doesn't seem terribly significant. I'll put my effort instead to the pinion seal on the rear axle, which is surely leaking.

 

[CDW6212R]

I think you're good, a worry when you see it drain out, but not a big deal.

If it were that newish member who kept saying he(and everyone else) had to use some new Ford Mercon replacement TC fluid $20 a quart, he'd freak seeing that Mercon V roll out of the TC. Mercon V isn't the right fluid for our TC's, but it's not the catastrophe that a 2011+ Ford could have over time.

I need to R&R my AWD again too. It was black the first time I changed it, and rough again a few months later. It works fine now and I hope it lasts until I get to doing the BW4406. Regards,

 

[Mbrooks420]

I luckily had the correct dextron/Mercon fluid, AND the 75w150 for the rear fro my last Mounty that I never got around to changing.

 

[CDW6212R]

I ran across a few quarts of the old Mercon/Dexron III in my garage recently. I'm using up old stuff too, it's painful to think how expensive all fluids are now, compared to what we paid for these old fluids.

 

[SWIGIN]

My buddy had a 94 F150 with a 5.0 and basically a 4r70W tranny (it was a AOD-EW) but it would fill the T case as fast as you filled the tranny. I guess time will tell how bad your seal is but either way it needs fixed.

 

[Mbrooks420]

Unless it was simply overfilled.

 

[SWIGIN]

Overfilling will come out the vent and I can tell you it was not overfilled.

 

[Mbrooks420]

I'm sure there's an orientation in which the truck could be jacked up to allow more fluid than if it were level. Otherwise, it'd have leaked out of the vent frequently when driving.

 

[imp]

I ran across a few quarts of the old Mercon/Dexron III in my garage recently. I'm using up old stuff too, it's painful to think how expensive all fluids are now, compared to what we paid for these old fluids.

@CDW6212R
At one time, I used ATF for just about everything needing lubrication, hinges, squeaks, rust-prevention. Terribly greasy, dirty hands could be easily cleaned using a spatch of ATF worked like hand lotion. Only the old Dexron, though, too many bad chemical additives later, even Type F was nasty. Now, cost is the factor. imp

 

[SWIGIN]

I'm sure there's an orientation in which the truck could be jacked up to allow more fluid than if it were level. Otherwise, it'd have leaked out of the vent frequently when driving.

I was talking bout my experience not yours, how would I know if your vehicle was leaning. Of course if it is leaning any direction it affects what the dip stick says is full but why on gods earth would anyone try to fill a tranny with the vehicle leaning that much?

The fact remains that if your seal was good it wouldn't leak into your T case.

 

[Mbrooks420]

I was referring to the fact the transfer case could have been overfilled by the previous owner if he had the truck in an odd position, such as having the car on ramps on one side.