# Pinion leak.



## rnoswal (Dec 2, 2007)

Odd one here. I have a pretty much stock 2005 GTO. I have owned the car for over 2 years now and have noticed a small oil leak at the rear end. I bought a pinion oil seal thinking that was the problem. I pulled the triple bolt yoke off, that pinion nut is a bitch! After getting it off, I noticed 2 things. First, the oil seal was dry, not a hint of a leak. Second was the inside of the yoke, where the pinion nut resides. It is pretty wet there.

After pulling the nut off, it appeared to be untouched and tight, I could see that this is where the oil had to be coming from. Looking at the back of the nut, where it should be seated on the yoke, I noticed about a quarter inch black area. The rest was shiney where it pressed against the flat portion of the yoke. I did not feel any play at the pinion before pulling the pinion nut. 

This is a first for me seeing this portion leaking. I don't suppose there is a soft washer that goes between the nut and the seat on the yoke? I don't know why it has been leaking more these last few months but there is a definate wet spot on my driveway and is wet under the rear end and body.

I imagine I will find a flat surface and try sanding the back portion of the nut to see if it is warped a bit. Has anyone out there seen this? And any reasons for it to start leaking? I check the breather for the rearend, it is clear. Maybe the rear gear oil is getting worn and thinning allowing it to seep by slowly. Don't know.

Thanks

Russ:confused


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## B-ville Goat (Oct 5, 2008)

You don't want a soft washer in there. Try either putting on a new nut or using a piece of sandpaper on a flat surface to flatten the nut you have, then if you want to seal it, use some thread sealer on the flat and threads.


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## rnoswal (Dec 2, 2007)

You are right about not using a soft washer. I did sand both the yoke seat and the nut bottom. The nut was a bit off and the yoke had some galling but was able to get them both clean. I used some permatex sealant and so far no leaks. I wish I knew why it started in the first place. The previous owner isn't around to ask if he had ever worked or had some work done on the rear end. 

Anyway, thanks for the reply and help on the fix.

Russ


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## svede1212 (Nov 1, 2005)

Not unusual for these cars


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## rnoswal (Dec 2, 2007)

It surprised me though to find a leak like that. I have worked on a few ford 9 in rear ends but have never seen this problem on the mating surfaces like my GTO. If that is not unusual is there any idea why it happens? I am sure there wasn't any recall on this as it probably isn't safety related, but could be once all the rearend fluid leaks out. I like not having a spot on my driveway now.

Thanks for the reply on this

Russ


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## svede1212 (Nov 1, 2005)

A little bit looks like a lot when it flings around. I have never heard of one going dry or locking up because of it. Some have leaking past the splines and some have had the seal bad. Sealant on the spine or seal replacement takes cae of it.


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## rnoswal (Dec 2, 2007)

You are right about the amount lost compared to how it looked. I thought way more was lost but actually only replaced about a pint. I did put sealant behind the nut, permatex, and on the splines. It has been dry for the few weeks since. I will remain hopeful, but still don't understand the why and how it happened.

Thanks

Russ


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