When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello. So I changed my differential fluid yesterday, but I noticed two things: First, that there were nowhere near 3 quarts in the differential, and second, that there was a slow leak coming from an area near the fill port of the differential. I see a black plastic o-ring that moves freely (cannot be tightened) next to a nut that attaches a line of some sort to the differential. I am not mechanically inclined enough to know what this o-ring's function is, nor can I tell if the leak is serious.
From what I can see it looks like if I just threw some JB Weld on the o-ring it would stop the leak, but I'm not sure if the leak is indicative of any serious problems. I also can't tell if it would be an important area to access in the future. For all I know it could be some kind of overflow line and maybe I overfilled the differential? I just don't understand what it is. Can anyone tell what the o-ring does, and perhaps what the line does? Thanks in advance, I'm pretty concerned.
It's basically right above the black bar to the right of the photographs in both pictures. You can see the nut and the o-ring basically is adjacent to the nut but spins freely.
Last edited by Superteeth; Feb 9, 2020 at 10:31 PM.
Those pipes where the "Oring" and nut are, those are the pipes to the diff oil cooler. If the leak is just seepage, and no drips, I wouldn't worry about it.
I don't know if it is normal for the black Oring (probably really a bushing) to be loose.
Last edited by ersatz928; Feb 9, 2020 at 03:54 PM.
Those pipes where the "Oring" and nut are, those are the pipes to the diff oil cooler. If the leak is just seepage, and no drips, I wouldn't worry about it.
I don't know if it is normal for the black Oring (probably really a bushing) to be loose.
Well, it's not really seepage either, it does drip enough onto the black shaft to cover it with oil. But that said, I didn't see this happening before I changed the fluid, and I do know it was low from the factory, so that led me to believe maybe I overfilled it, although it was level and dripping out the fill hole?
I was reading around and it appears that there is a vent line for the differential as well, which leaks oil if the differential is overfilled...this isn't where the vent line would be though, right? Everything I read about the location of the vent line indicates it's above the differential, not towards the bottom.
Assuming it is what you think it is, it wouldn't hurt to spray some sealant on it?
Actually, turns out that I'm probably leaking more fluid than I initially realized. It appeared to be less than I thought because there wasn't much accumulating on the floor, but when I drive it appears that it's getting all over that black shaft and blowing onto the mufflers and the bottom of the rear diffuser. I'm led to think that perhaps that was why there wasn't much fluid in the differential when I drained it...although I would think I would have noticed the smell of burning differential fluid from the start. Is there a low differential fluid light? Because I wouldn't want to keep driving if it could cause the differential to get dangerously low.
That black plastic ring is retainer to keep the clip holding the cooler line in place. It doesn't tighten, just clips over the fitting. If you slide it off the fitting you'll see what I mean.
.
That black plastic ring is retainer to keep the clip holding the cooler line in place. It doesn't tighten, just clips over the fitting. If you slide it off the fitting you'll see what I mean.
.
So is it possible that it’s just loose? Because I can’t see where it could possibly be damaged. What size is that nut anyways? I’m going to try tightening it.
Well, it looks like there's simply not enough room to even turn a wrench once it's on the nut. Even so, it really appears to be on tight. I don't see how it could have been loosened in the first place anyways, but then I don't see how the line is leaking if the nut isn't loose, because that line is solid metal, not some flimsy-feeling aluminum. Looks like I'm trying sealant next, I've definitely pinpointed the location of the leak to that fitting and if it's really a line to the cooler (which I can figure it is because I traced the line to where it was leading to the rear vent area of the car) then it shouldn't be a problem.
I'm sure someone is wondering why I don't just take it to the dealer to fix under warranty, but I was reading another thread and apparently GM doesn't consider the line a warranty item! And even so, they'd probably have the car scattered across the shop for 2-3 weeks just to fix that cooler line...
Differential fluid leak from plastic ring
