Rear Diff Pinion Seal
 

I've got a 2006 F-150 FX4 with the 5.4L engine and the 3.73 LSD rear end. I was checking out my rotors all around this weekend after a trip to the mountains and noticed some sprayed fluid around the axle/shrouding areas. After further inspection I noticed some sludge/fluid buildup on my rear axle/differential as well. I took it over to the local mechanic and he told me that it was probably the rear pinion seal in the differential. has anyone ever had this problem or have any information for me about what's going on/fixing it?

just make sure if you go to the parts store that they give you the right pinion seal. Apparently, when the 9.75 rearend is looked up, they will give you an 8.8 seal. This happened to me at 3 different parts store chains.

awesome thanks for the heads up, do you know the cause of this? just normal wear and tear on the 9.75"?

My 06 does the same. When I first noticed it over a year ago I took it to the local stealership and they told me it wasn't leaking, it was excess grease from the factory. I looked at the guy and asked him if he thought I was stupid. I had them sign the work order and what they told me. I am now trying to get them to replace the seal which I told them was leaking.

yea i didn't even bother with the stealership, they quoted me at 250-300 for the job and my mechanic told me he would service the whole rear end for 200 final price

I used this info to change my axle seals...could help you with the pinions.

https://www.f150online.com/forums/20...lots-pics.html

mine is leaking as well my mechanic told me to get the seal and he would do it for like 50 bucks

those pinion seals are a breeze to do $18.00 for the seal i think from ford and about 1/2 hour to get the old one out and new one in i do them quite a bit at work..."ford dealer" if any one has questions just pm me and ill help!

They're easy for you because you do them everyday, for the average person on his back in the garage, not so much.

I've done dozens of pinion seals on a variety of vehicles, but when I did the one on my '04 last summer it took the better part of an afternoon. Getting to the seal is the hard part, the seal itself is a breeze to pop out and in.

Just buy the seal from the Ford dealer, they'll get you the right part the first time.

I have the same problem. My 06 has 23000 mi on it. I also noticed the oil spash stains on the tailpipe and under the bed and on the spare tire. I cleanded it up and came to the conclusion that it only happens when i drive at 85-90 mph.(lonely tx road trips) . When i drive at 80 mph it doesent leak. I noticed my dads 05 is bone dry.( identical trucks). i have seen alot of 06 that look like they leak.

I took my 06 in about 3 weeks before the 3/36k expired and they replaced it because of a leak. Must be a common 06 thing then.

I just noticed the same thing on my 06. I just did a 1600 mile road trip and have to return in 2 weeks. Without a garage or any of my tools I might just take it to the stealership here and pay my 100 deductable. not that its a good thing, but I am glad im not the only one. I always have f150online to check out my problems

Had mine changed 6 months or so ago. I have the extended warranty and Ford picked it up.