Water In Your Differential How to Diagnose Differential Leaks That Let in Water

There I was trying to do a rear differential service, what do I get coming out of it? Water. Great.

Hey, friends, it's Len here from 1A Auto. I'm doing this rear differential service, and I found that I have water coming out of it. The next thing that I need to do is go ahead and drop this pan and see exactly how much contamination is going on. I'm just gonna try to separate this a little bit. Oh, man, this is bad. Oh, nasty. Whenever I'm changing any fluid, whether it's oil, transmission fluid, or even differential fluid, I always like to take a sample of exactly what came out so I know what I'm dealing with. Inside this cup right here, you can tell that it's got a lot of water mixed in with it. It's all sitting down along the bottom right here. And then the rest of the fluid is kind of like contaminated with the water mixed with the gear oil. Now, this is no good for a lot of things that are going on in the differential. So, let's pop the cover off here and take a look. Now, you can see where there's different gears inside. You've got this one right here, and then, of course, you've got the ones that are connected directly to the axles.

Now, any of these that might potentially have rust on them could potentially cause a binding or even noise. You might even hear a little bit of a chatter when you're driving down the road. If it has rust or debris inside these areas in between, it's going to cause some damage to them. You're gonna see a whole bunch of lines and scuff marks, you might even see large chunks missing if the damage was bad enough. Now, luckily for us, we kind of caught this in time. The moisture doesn't look like it really set into any of the gears right here, it didn't rust it up any, I don't feel as though there's any damage on this. If, for some reason, you had a light coating of rust on it, it's probably not too big of a deal. But if there's large coating or large chunks of rust in there, you're gonna want to try to clean it up a little bit. It's gonna be hard to do because, of course, there are a lot of different teeth on this that you're gonna have to try to spin to be able to get to, but it's something that you're going to want to do if you don't want to have noise. Also, besides the gears inside your differential, you're also going to have some bearings.

Now, right along this side right here, you can see one of the bearings. This one's pretty much the easiest to see. When you spin the axles, this is going to want to spin a little bit, especially when this right here spins. This will spin when you turn the driveshaft itself. If the rust gets inside of these bearings right here, once again, you're going to hear some noises, and it could even bind up over time, especially if there was a lot of moisture in here. Now, there isn't only one bearing though, there's several bearings. I'll go ahead and mark them for you. You're gonna have a bearing behind this area right here. Same on the other side. You're gonna have another set of bearing right down here, and then on the other side of the truck as well. And towards the front of the differential, you're also going to have another bearing in this area right here. Now, if any of these areas have rust or debris built upon them, it could potentially cause noises or premature wear while you're driving it down the road.

Now, you might think that the differential is supposed to be completely sealed, but it's actually not. It needs to be able to breathe a little bit because as you're driving, there's going to be pressure getting built up inside this differential, whether it's from heat or even just the movement of the fluid. That pressure needs to be able to escape, and then, of course, as things cooled down, it's going to need to depressurize a little bit. So, there needs to be a breather. The breather is going to be located on the top of your differential. If you're driving through very wet conditions, may be driving through a lot of puddles of water, or maybe even you tow a boat of some sort and you're backing down into the water, there's a possibility moisture is making its way into the differential through different areas. You've got the vents. Now, if it's damaged in any way, like this one right here, it's got a little rip in it, of course, moisture can make its way in.

Something else I noticed while I'm wiggling around, it doesn't have a clamp on it. This one pretty much just wobbles all around, and it could potentially let moisture right inside there. Not to mention, it's really not in the best condition. Let's go ahead and follow that all the way up to the top. And this is one of the more common areas. Generally, there's going to be some sort of clip up here that holds it up nice and high. That's going to make sure that moisture can't make its way in unless, of course, you would submerge the entire rear end of your truck. Now, if this was hanging down, like this right here, obviously, moisture is going to be able to make its way in. It's sitting very low. It could potentially get stuck in a puddle, or like I said, if you're backing a boat into the lake. Otherwise, there should be a little one-way valve on it. This one's just wide open for some reason. That's not any good. Moisture can make its way down this tube, all the way into the differential, and that's going to cause an issue.

Another area moisture can make its way in is through pretty much any seal. Up along the front here, you're going to have your pinion seal. If you can see your oil coming out of it, more than likely moisture can make its way in. You're also going to have some axle seals located behind each wheel. Just go ahead and follow the tube all the way down towards the wheel. And, of course, you're also going to have the pan seal itself.

Now, you can tell on this one, somebody used the original seal, which is what you should use, but then they also used some gasket maker, kind of, like, a double gasketing situation. It doesn't make much sense to me, but that's what they did. That can, of course, cause a discrepancy where moisture can make its way in between, and then you'll have something like this where you can see that moisture was making its way in between the pan and the differential itself. If you have moisture inside of your differential in here, there's the probability you're going to have some moisture inside these tubes as well. Generally, there's going to be some fluid that sits inside there. That's why they're seals at both ends of the axle tube. You want to make sure you get that fluid out of there. So you could gently tip your differential to one side or the other. When you do that, the fluid is going to come down like this, and then it'll make its way into this area where it can drain. After it's fully drained from one side, just go ahead and do it on the other side.

So, now we're going to talk about fixes. Obviously, you made sure that you got all that old existing fluid out of there. The next thing that you're gonna want to do is make sure you check around to see where that leak came from. Where did the water make its way in? But if you found that the vent tube was cracked or broken in any way, it really only makes sense to guide and replace it. It's just a rubber tube, it's not very expensive. Just make sure you get the little bubble at the end, or the vent cover right up there. You want to make sure moisture can't make its way in. Other than that, if you find that you have axle seal leaks or even a pinion seal leak, you're gonna want to make sure that you replace that as well before you go ahead and put in brand new fluid. When you apply fluid, make sure that you use the manufacturer-specified fluid.

Okay, friends, so that's what I've got for y'all on why you might have contaminated or moisture inside of your rear differential. I hope this video helped you. If it's something that you think somebody might want to know, go ahead and share it with them. It will mean everything to me. If you liked the video or loved the video, go ahead and smash on the like button for me, it'll mean the world. While you're at it, go ahead and subscribe, ring the bell, that way there you, all of your friends can be kept up with all of our latest content. Thanks.