I changed the Power Transfer Unit fluid in my ’06 Mercury Mariner Hybrid this morning. It has about 13,000 miles on it. A few weeks ago, I noticed a fluid leak from the PTU very similar to this one:

http://www.escape-central.com/1forum/showthread.php?threadid=27228

As in that case, the vent tube was loose. You might want to check yours. The dealer fixed mine under warranty, but I suspected that he didn’t replace the fluid that leaked out. There’s only about 12oz in there, so a small leak could be a substantial percentage of the total.

Anyway, I decided to replace the fluid myself. I found it to be fairly easy. I used Mobil 1 75W-140 synthetic gear lubricant (about $15 for a quart) and Motorcraft TA-30 silicone gasket/sealant (amazon.com has it for about $18).

I removed the drain plug and the fill plug and let the existing oil drain. It was a shimmery gray color… kind of disturbing. There was an astounding amount of metal particles attached to the magnetic fill plug. I didn’t measure how much old fluid was in there, but it wasn’t close to empty. Seeing the volume coming out, I was no longer worried that it had been running seriously low.

I used a wire brush to clean the old sealant from the threads on the two plugs. Then I put some new sealant on the drain plug and put it back in. Then I filled the PTU with the 75W-140 through the fill hole until it started to run out (vehicle on flat ground). Then I put some new sealant on the fill plug and put it back in.

In retrospect, I’m glad I changed the fluid instead of just topping it off. There looked to be a lot of metal in there. I am convinced that these "lifetime" lubricants aren't a good idea.

 

I really wish I read this about a year ago. Currently waiting for my 2007 MMH to get out of the shop waiting for a PTU replacement. How often would you suggest changing the PTU fluid?

 

You just replied to a three year old post and the OP's profile states:
Last Activity: 09-26-2009 11:17 PM.

 

Yes, I did. You are correct about both the age of the post and the fact that the OP hasn't been on for quite some time. The link gives a lot of good information on what to look for to make sure your PTU isn't leaking out of the vent along with pictures of what to look for. Goal was to make sure any new hybrid owners or someone new to the site checks for this. Could save a $1,000 to $2,000 repair cost. Most maintenance garages do not check for this.

 

Here's the PTU Vent Bolt Hole Leak TSB: tsb09-04-04.pdf. It's hard to believe that it goes back that far!

 

If this works and I'm able to attach the image, here is a picture of my PTU when it started giving me problems. I'm not sure why I didn't notice it while changing my oil or doing inspections. Without specifically looking for it, I passed it right over. I guess I expected the bottom side of my car to be dirty so I never suspected a leak. Looking at it now, it is obvious. The picture isn't the best, I was taking a picture of where the drive shaft met the PTU. All of the fluid leaked from the vent bolt on the PTU. In my defence, when I first took my car in because of the strange noise, the repair tech missed this as well. 5 days later, my PTU completely failed. I took it back in and they diagnosed a PTU failure. The dealer claimed that I abused my car (I have a trailer hitch receiver installed and must have overloaded it) and that is the reason for the failure so with 54,000 miles on it, they are not replacing it under warrantee. I contacted Ford's customer service and explained to them that the reason for the PTU failure resulted from the vent bolt leak and lack of fluid and not abuse because I only use my trailer hitch for a bike rack. Ford's Customer Service is currently contacting the dealer to discuss the situation with them.

 

Bob, was there ever any oil dripping on the garage floor? Is this something that can be inspected for without putting the car on a lift?

I'm thinking I might have the dealer do my next oil change and check for this problem at the same time.

 

Must be a 2" hitch, correct? If so, that's one reason I've always been against the larger than OEM hitch suggested by the aftermarkets. You leave yourself wide open for them to accuse you of abuse which if anyone reading in this forum is common if not bragged about practice.

 

No I never noticed any oil on the floor in the garage but I have about 2 miles of 25 mph through town to my house and I live in the country with farm equipment throwing dust and dirt on the road which is probably why my PTU was so dirty.

You are exactly correct. It is a 2" Class III hitch. My wife and I bike a lot and we spent a little over $2,000 on our bikes so the extra $75 for the larger, stronger hitch made sense to me. We have two young boys and we frequently take our bikes to my wife's parents house and ride for an hour or two while grandma and grandpa watch the kids. Its one of the things my wife and I try to do together to keep us sane. :0)

 

I understand the bike issue but the possible overcapacity potential of the hitch can cause a dealer to think of abuse. Just like anytime I take my '09 FE in for anything, I remove my ScanGuage-II because I know others have had dealers question its functions.