Hello, I've got a 2008 mercury mariner 3.0 v6 4wd. I've been doing a lot of work underneath and I've been seeing red fluid droplets hanging out around the passenger right side cover on the transfer case. Everytime I wipe it off I come back to see it back again so there is for sure a leak. I can tell somebody has been in there before and did a ****ty job with a gasket sealer. Possibly the transfer case was replaced or something I don't know. Now what concerns me is that the fluid is red, from my understanding transfer case fluid is supposed to be like oil, just sort of brown or something. Am I wrong or?.. I hope I'm wrong because if transmission fluid is getting into my transfer case than I'm probably leaking it from my cv input seal. But lets just say the fluid is supposed to be red, my game plan is to first drain the transfer case fluid, pull the passenger side cv axle, unbolt the cover, put some gasket sealer on (AND do a better job than him!) and then put it all back together... So I guess my questions for you guys 1. Is the transfer case fluid supposed to be red? 2. Does my plan sounds right or am I missing anything and or major things that have to come out of the way in order to take that cover off? The only major thing I can imagine being in the way is part of the exhaust but I'm fairly certain I can slip it past it. Thank you I hope somebody knows more than I do about this kind of stuff. This is my first ford product, use to be a volvo guy so lots of things I need to learn.

 

My xfer case had normal EP gear oil as I’d expect. When I was under looking I reckoned the rear exhaust manifold would need to come off to move the xfer case sideways enough to remove it, there is quite a long drive coupling feeding into the diff from the xfer case.

I’d suspect you have trans fluid leaking and finding its way down to the xfer case joint but inspection will tell. There are fill and drain plugs on the xfer case IIRC (drain only on the rear diff), so no biggie to drain and refill.

 

thanks for your response, just an update: I figured the leak was super small and I took it for a quick drive to the market. On my way I began hearing odd noises from the transfer case and before I knew it it was grinding. I pulled over and got it towed back to my house. I pulled the plug on the transfer case and grey metallic fluid came out and hardly any came out. I then flushed it with gear oil and put new gear oil in it and drove it again and it still grinds sometimes. Basically it needs a new transfer case. After filling it with gear oil though it does not leak anymore. I got in contact with the previous owner and there was a shop that changed the transfer case fluid. My hypothesis is that some moron put ATF in the transfer case when they changed it even though the owners manual says use gear oil, and because the ATF has extremely low viscosity compared to the gear oil it just was able to seep out through the gasket. And eventually so much seeped out it ran it dry. Going to make a claim to the shop and get it warrantied. Does everything I said add up and make sense?

 

It's a hypothesis.

Prove it.

 

My daughters 2005 Escape AWD was leaking transmisson fluid out the passenger side.What I eventually discovered is that the axle seal is actually in between the transfer case (some call it PTU) and the transmission so if that internal seal is worn it will leak transmission fluid out through the right side. The input shaft from the transmission to the PTU is a hollow tube and the right side axle passes through it.If you pop off the plastic seal protector on the right side the seal that you see is the input shaft/ transfer case seal so if it is leaking transmission fluid replacing that seal does nothing.