Rear Differential in water

[Chris19]

Hey all, I’m on vacation for a bit and was curious about the rear diff (3.21) in my 2014 Ram 1500. I was out towing my boat and have never submerged the rear end because I always use a launch. I ended up having to mostly if not fully submerging my rear and front end. I know the front diff’s fill and drain plug are threaded but the rear’s drain plug is threaded but the fill is that rubber cap. Are those things good at keeping water out. Truck wasn’t in for long couple minutes at most. Thanks

 

[mikeru]

I wouldn’t worry about the rubber plug. If it keeps fluid in it will keep water out. I’d be more concerned about whether you submerged the diff vent tubes. Pull the fill plugs and check the condition of the diff fluid. I should be fairly obvious if there is water in there by how the fluid looks.

 

[magman777]

This brings to memory something I learned the hard way many years ago when I drove truck over the road. I arrived at a plant that I was delivering at the next morning, so I opened my trailer doors and backed down the ramp to the dock. I hadn't noticed the water at the bottom of the ramp & I doubt it would have stopped me if I had noticed it, because this was a lesson not yet learned LOL. So I woke up in the morning, the truck shaking, which meant I was getting unloaded. Left there and headed down the road. Can't really remember how long it took but another driver started yelling at me on the CB to pull over, I was on fire. Well I wasn't on fire YET but soon would have been. When I backed those warm axles into that cool water, it cooled the bearings down and sucked the water right into the axle hubs through the seals. Never would have thought of that but it happens. Not sure if that helps, but sure something to think about when getting into water with your axles.

 

[GTyankee]

pull the Fill Plug
Stick your finger in the hole
When you pull your finger out of the fluid, you will know if there is water in there.

By the way, while you are under there, look at the Rubber Vent Tube
Sometimes the end with the One Way Valve drops down, it should be up near the trucks bed.
Some people who drive in deeper water, have put that end of the hose, as far up in the tail light body cavity as it will go

 

[Jeepwalker]

....When I backed those warm axles into that cool water, it cooled the bearings down and sucked the water right into the axle hubs through the seals. Never would have thought of that, but it happens.

It happens on trucks too sometimes. Bugs can build nests in the vent tubes, or mud can get in there and plug it. If/when that happens it can push fluid out (under pressure) when things get warm. And 'suck' air/water in when it cools down. So yeah, vent tubes are often overlooked but the smallest thing can sometimes cause major problems..like you say.

OP, you ca check your tk's fluid pretty easy. Drive the truck a mile or so, the remove the filler cap and draw out some fluid with a SUCTION GUN... and squirt it in a glass container. If it appears 'milky' at all, then you should change the fluid right away.