Question regarding transfer case fluid

[grey26]

I decided to check my transfer case fluid this evening on my 2000 Ford Explorer V6 SOHC 4 wheel drive. I removed the fill bolt (The bolt directly below the rear driveshaft towards the pax side, and NOT the bolt marked "drain" which is towards the driver side) and about 1 quart of fluid came out. I've had the vehicle since it was 4 years old and I know I haven't checked the fluid level before tonight. Was/Is it normal for Ford to overfill these for some reason when they were being built? Any other ideas as to how this happened? I read somewhere that some seal or something in the transmission could fail possibly causing fluid from the xmission to seep/flow into a transfer case...going to check the xmission fluid next but it's been fine in the past and checked fairly reguarly. I guess I'm also looking for some reassurance now that the fluid is now at the correct level and not underfilled?

Update: Just checked xmission fluid and it was fine. It was changed about 3 years ago and I've never thought I had a xmission leak (ie, I've never had to add xmission fluid outside of the drain/fill). Also, I noticed there is oil around the output shaft, above the fill bolt. On better inspection, there's a little bit of oil on the undercarriage as well...kind of in a line moving from driver side to pax side. No idea how it could get up there???

 

[imp]

@grey26
Was the vehicle level when you checked the fluid level? If jacked up in the front, a higher than actual level would be presented. Transfer of leaked transmission fluid from it's rear seal, through the T.C. front seal, is unlikely, though maybe possible. Especially unlikely in your case since the transmission fluid level was normal. imp

 

[koda2000]

As far as I know, the trans can't leak fluid into the transfer case, nor can it be overfilled if level. As mentioned, if your trans fluid level has never been low it can't be leaking. If fluid poured out of the transfer case when the fill plug was removed, perhaps the vehicle wasn't level.

As far as "the line" across the underside of the truck. This happens when you have an output seal leaking. It flings fluid across the underside of the vehicle in a straight line.

 

[grey26]

Thanks to you both for your replies. The vehicle was on fairly level ground in a concrete parking garage (bottom floor). I spoke with a Ford tech this morning and he said that in his experience, he's never seen an "overfilled at the factory" transfer case and that most likely the seal between the xmission and the xfer case has failed. I've read numerous reports on other forums/posts that state this seal failing isn't unheard of. The Ford tech also seemed to think the output shaft seal on the xfer case was the culprit for the "line of oil" that I mentioned as well and quoted me $700-$900 to fix. He indicated it was about a full day's worth of labor which is, I'm assuming, the great majority of the cost. Is that something fairly simple/straightforward for a backyard mechanic like myself? I didnt even want to ask how much to replace the seal between the xmission and xfer case! He ended with recommending I just keep careful watch over the xmission and xfer case fluids after i drain/fill the xfer case this weekend and go from there. If the levels in the xmission and xfer case are stable, don't worry about it. He also suggested I wipe down the undercarriage and see if any signs of oil return around the output shaft. He said if it's just wet/slick he wouldn't worry about it but if I have actual dripping, which I've never noticed, the output shaft seal should be replaced. I'll add that to the list of other things I need to do: replace pinion seal on driveshaft/rear differential and isolate fluid leak at front differential/axle. Fun fun...

 

[koda2000]

Thanks to you both for your replies. The vehicle was on fairly level ground in a concrete parking garage (bottom floor). I spoke with a Ford tech this morning and he said that in his experience, he's never seen an "overfilled at the factory" transfer case and that most likely the seal between the xmission and the xfer case has failed. I've read numerous reports on other forums/posts that state this seal failing isn't unheard of. The Ford tech also seemed to think the output shaft seal on the xfer case was the culprit for the "line of oil" that I mentioned as well and quoted me $700-$900 to fix. He indicated it was about a full day's worth of labor which is, I'm assuming, the great majority of the cost. Is that something fairly simple/straightforward for a backyard mechanic like myself? I didnt even want to ask how much to replace the seal between the xmission and xfer case! He ended with recommending I just keep careful watch over the xmission and xfer case fluids after i drain/fill the xfer case this weekend and go from there. If the levels in the xmission and xfer case are stable, don't worry about it. He also suggested I wipe down the undercarriage and see if any signs of oil return around the output shaft. He said if it's just wet/slick he wouldn't worry about it but if I have actual dripping, which I've never noticed, the output shaft seal should be replaced. I'll add that to the list of other things I need to do: replace pinion seal on driveshaft/rear differential and isolate fluid leak at front differential/axle. Fun fun...

$700-$900 to replace the transfer case output seal? I replaced mine (for the rear shaft) a few years ago on our AWD 2000 Mountaineer. IDK if a 4WD t-case seal would be different (maybe it is). I think I paid about $5 for a new seal. removed the rear d/s from the flange, removed the nut and pulled the flange off, popped out the seal, installed the new one and drained/refilled the t-case, which took about 1 QT of Dex/Merc III ATF.

 

[grey26]

$700-$900 to replace the transfer case output seal? I replaced mine (for the rear shaft) a few years ago on our AWD 2000 Mountaineer. IDK if a 4WD t-case seal would be different (maybe it is). I think I paid about $5 for a new seal. removed the rear d/s from the flange, removed the nut and pulled the flange off, popped out the seal, installed the new one and drained/refilled the t-case, which took about 1 QT of Dex/Merc III ATF.

Perhaps that $700-$900 was to replace the internal seal between the xmission and xfer case. That would make more sense. Not sure if I got confused when i was taking my notes or if the Ford tech misspoke...in his defense, i'll take the blame for it. On another note, I'm glad it looks like I can fix the output shaft seal easily/inexpensively!

 

[imp]

@grey26
Having had my T-cases out of both my 2nd. and 3rd. Gens, I can say, the T-case to Adaptor was gasketed in both vehicles, and could readily see how a failed transmission output shaft seal could fill the cavity within the adaptor, and having worked in the oil seal industry many years, I know seal lips prevent oil from passing in ONE DIRECTION only. Thus oil could easily enter the T-case past it's input shaft seal. But, the loss of fluid from the trans. would certainly be noticed if it were of any quantity. imp

 

[KristofferJ]

...if over filled I would drain to see that there was no water.
though not sure how that would get there as I've not looked to see if there is a vent that could allow such a thing?.

draining to check for metal particles isn't a bad idea anyway.

 

[drdoom]

700 dollars should replace all seals in t-case plus bearings.

 

[drdoom]

Kristofer good post. The vent should definitely be checked. Koda the seals are the same on 4x4 and AWD cases, except obviously the little one for the encoder which the AWD does not have.

 

[drdoom]

The only way to get ATF from transmission into transfer case is to park on a VERY steep uphill grade, for a very long time. Not really plausible any other way.

 

[grey26]

I drained/filled the xfer case yesterday. I didn't see any water or any metal particles. I topped off both xmission an xfer case and they are both "full" so I can now easily tell if the xmission is leaking into the xfer case. I'll plan on keeping an eye on them and am thinking i'll drain/fill again in a month or so and replace the xfer case rear output shaft seal at the same time since it appears fairly easy and inexpensive.

One more question - The Ford dealership service tech I spoke with and my Haynes manual both say to use Mercon V ATF in the xfer case...however, on the back of the Ford/Motorcraft Mercon V bottle it says 'Do not use in transfer cases.' So now I'm a bit confused...am I ok using Mercon V in it or not?

 

[Mountain_Dewd]

You should probably be using Ford Fluid XL-12 Transfer Case Fluid.

 

[grey26]

You should probably be using Ford Fluid XL-12 Transfer Case Fluid.

I called another dealer and he confirmed I'm supposed to be using Mercon V ATF. He said the newer xfer cases have something else they're recommending, I'm guessing it's the XL-12 although he didn't state that, which is why the new bottles of Mercon V say not to use in xfer cases.

 

[Mountain_Dewd]

I'm pretty sure XL-12 Transfer Case Fluid was created as a replacement for Mercon ATF (which isn't manufactured any longer). The online owners manual for 2000 Explorer calls for Mercon ATF for Transfer Case and Mercon V for Transmissions (except manual transmission).

I have a 2007 which has a different transmission and transfer case, but I went through a lot of research to find the correct answer for my vehicle. From everything I've read, the Mercon V bottle is correct and shouldn't be used in transfer cases.

 

[grey26]

Found this link: https://www.fcsdchemicalsandlubrica...ansfer Case Fluid&category=Transmission Fluid

Quote from the website:
"Transfer Case Fluid is recommended by Ford Motor Company for use in transfer cases driving front axles on Ford, Lincoln and Mercury AWD/4X4 vehicles. For use in transfer cases where MERCON® ATF was previously recommended. Do not use in AWD vehicles equipped with a transaxle"

Just got off the horn with Ford corporate support. They said they are still recommending Mercon V for my vehicle. When I asked about why the Mercon V bottle says not to use in transfer cases, he said he didn't know and that he would "forward it on to the right department to have them check into it."

 

[Mountain_Dewd]

In this guys video (he seems pretty highly regarded on a lot of Ford sites) he gives pretty strong warnings about putting Mercon V in transfer cases.

 

[grey26]

Thanks for sharing the video, Mountain Dewd. I'm heading out on vacation this weekend (flying, not driving) and will change the xfer case fluid with XL-12 and replace the rear output drive shaft seal in a few weeks at the same time. My commute to/from work is 1 mile so the total mileage I'll be driving it with the Mercon V fluid in it isn't that much overall.