Front Diff Leaking/Overfilled at the same time?
 

Hey everyone. I noticed a drop of gear oil sticking to the bottom of the diff where the cable housing attaches to the differential. I wiped it off and it smelled like gear oil. It is leaking a spot the size of my fist every 24 hours. I had a Posi-Lok system installed just under 2 months ago. I took it back to the same shop and they believe that it is from above (they think power steering fluid, but I am not noticing a significant drop on the dipstick). What really confuses me is that I went to take the fill plug off to top it off yesterday and it started to gush out, meaning it was overfilled. The last time I took it off was when I changed the fluid in December. The car was on ramps when I did that (with the front end elevated), meaning that was probably why it was overfilled, but where could it be leaking from?

Also a side question: Would my Posi-Lok system engage easier if I use synthetic 75W-90? I have Lucas 80W-90 in there now.

Problem solved: It was the left axle seal. The left CV axle was wet and the owner of the 4x4 shop believed that the fluid was slowly travelling along the bottom of the axle to where it was dripping from. I don't know why I didn't realize this earlier because that axle was wet for over 2 years since the CV axle was replaced. I thought it was oil from the pan above. Now to my next question: What is the safest way to remove all the engine and gear oil mess from under there without damaging rubber parts?

The left CV shaft is now dry and it is no longer leaking from there, but for some reason, it is still leaking from the same place. It smells like gear oil. This is really confusing. The oil pan above it is wet with motor oil, but how could it still be leaking gear oil? Where else could this be leaking? It still looks like it is coming from the bottom of the cable attachment housing. I washed it earlier in the car wash and there is a drop forming again. The 4WD still works and the only time it makes noise is when it binds up when it is in 4WD and makes a faint groaning noise. That means the differential itself is still fine, correct? Means it was never run dry? I did notice some glitter in the fluid (no chunks) when I changed it in January.

It sounds like it is leaking from where the axle tube bolts to the side of the diff. You can unbolt that(i think theres 5 bolts) and reseal it.

Ouch. That is a bad repair, isn't it? How could the 4x4 shop miss that? They claimed that the fluid was leaking out the left CV shaft and traveling along the bottom of the differential case. So it really is leaking from 2 places? It left a spot the size of a dime and it has been parked for the past 3-4 hours. Should I even fix it at all or just top it up every oil change? It is never low for some reason. It is always full no matter what. I don't know why. It definitely smells like gear oil.

Is it possible to put some RTV/Silicone or epoxy (I was thinking JB-Quick since I already have it) around where it is leaking? Photo attached.

It shouldnt be too had to do. You will have to remove the right side cv shaft. Then just unbolt the bolts you can see in the pic and reseal it. Bolt it back down, put the cv shaft in and your good to go. Unless you just want to fill it all the time. You want to make sure it doesnt get too low though because you will ruin the bearings.

Ok thanks. What are the signs of bad bearings? Would the shop have noticed when they replaced the axle seal on the left side of the axle? I already had a bad shift fork and bearings when we bought this truck in 11/2007 that cost alot to fix at GMC. The 4WD was toast, but it works fine now. As I said, the only noise is a faint groan when I make a sharp turn with it in 4WD and it binds, but I don't put more stress on it as soon as it makes the noise. The axle can be hard to engage at times since the truck has to be moving and the gears have to be in just the right position to lock in. I have a Posi-Lok setup. With one of the front wheels jacked up with the truck in 4WD, I can only rotate the wheel about 3 inches before it starts to rotate the opposite CV shaft and the front driveshaft.

Is it possible to fix this from the outside without tearing it apart by putting sealant on the outside? What would be the best to use? Is there a spray or tube of something that would make it stop dripping? It doesn't seem serious, but I just want it to stop dripping.

EDIT: I found something online. Permatex 82099 Spray N Seal Leak repair?

EDIT2: What about loosening the 3 bolts on the cable attachment (just enough to create a small gap) and using a thick bead of oil resistant gasket maker from Walmart around it? How far can I loosen the bolts without causing damage to the cable or the hardware attached to it?

Just in case it helps, the attached photo shows the fine glitter that I was talking about. This pan was only used for a couple oil changes (that had no metal) and the transfer case and the front axle fluid change before I stopped using it once I got a bigger pan. The transfer case and front axle fluids were 30k old when I changed them using this pan. Does this glitter mean problems or is it only there because there is no filter or magnet?

As I asked in my last post, would loosening the 3 bolts on the axle cable housing and putting RTV gasket maker in there between the center cable attachment and the outside edge solve this? What is the proper procedure for using RTV?

You can do whatever it is you want to do. Stop waiting for someone to respond and get in there. Try things out. See what works. I wouldn't use anything but RTV to seal it back up. Anything on the outside is just a waste of time. You can pull the engagement cable housing off and try sealing that first. Worst case scenario is that it doesn't seal up the leak and you have to pull the passenger side extension housing. But that is just common sense. :icon_shrug:

Your picture doesn't help anything. It's blurry and since you did not clean the pan between changes, any "glitter" in there is useless in determining if there is a problem. You do not know where it came from in the first place so the problem could be in any one of the three locations the oil came from previously. ALWAYS clean your pan if you want to assess the health of your vehicle's oiled systems. If you don't, you might as well just not even look at the condition of the oil.