My wife has a 2005 GT convertible, and about a year ago I noticed a small spot underneath the rear differential When I crawled under, it was clearly coming from the pinion seal. I filled it, and figured I'd replace the seal, but then it didn't leak for months. Then it would leak for a while, and stop again. Two months ago, it was leaking worse, actually leaving a puddle rather than a spot. I was in the process of moving, so I was just refilling it every week. Then it stopped again.

In my experience, seals like a pinion seal (or a main seal or a transmission rear seal), once they start leaking, they don't generally stop.

Has anyone else had a similar experience? The only thing I can think of is that maybe the little vent on top of the axle tube is clogged? I cleaned it off last time I checked the fluid, and it hasn't been leaking. I will probably go ahead and replace the seal, but we're moving again (having a house built) in December, so it won't be before then....

Any input is appreciated.

Importsmasher

 

I'm thinking you might have worn pinion bearings, allowing the pinion flange to change the way it contacts the seal.

When the seal leaks, it is mostly due to the age of the seal itself. However, over time the seal wears a slight groove in the pinion flange. This groove can allow the pinion to leak despite having a new seal in place. There are seal saver kits available, which are basically a thin metal sleeve that slides over the pinion flange, but they tend to be just a little pricey, and for just a few dollars more, you can get a whole new FRPP flange.

 

I thought about that. I forgot to mention it in my original post, but I did lift the car up and tried to move the pinion/driveshaft side to side, and it is tight; there is no freeplay. The groove in the pinion flange is a possibility. I have seen that in harmonic balancers on my old Pontiacs, and I have installed sleeves on those.

Thanks,
Importsmasher

 

Could it be the axle vent / breather? That would tend to barf somewhat intermittently depending on how the car was driven. It seems to be a pretty common problem and in my case the barfed lube worked its way from the vent to the pinion seal area. I installed a JLT axle overflow reservoir and it's remained clean and dry since.

 

Just cleaning off the outside of the vent fitting may not be enough. I'd remove it and make sure it was free-breathing under the cap and inside as well. After wiping off the heavy crud from my car's fitting, I removed it and sloshed it around in a tuna-can size container of gasoline (#becausehandy), and the gas still turned pretty dark.


Norm

 

Thanks, Norm, I will do that before I go through the effort to replace the seal.

Importsmasher

 

It might be easier to detect play by trying to wiggle the flange in/out of the pumpkin, rather than side-to-side.

 

Ours did that ..... then I removed the vent and replaced it with a straight hose type fitting and attached a hose that runs up and then back down into a frame opening. Top of turn is secured to frame. No more drips after that.

Factory vent has a spring under cap that presses against a disc over the end .... so it opened under pressure ..... but first you gad to build that pressure ..... whatever that was. I have other vehicles that have the hose.