Sunk my rear end for about 10 minutes... how urgent is a rear diff fluid change?

Just pull the fill plug and dip your finger in the oil like said. Why make a big deal out of changing it if it is clean? Sure change it when you can to be safe but if you drove it more than a mile it is going to be mixed and have a hazy milk look to it or be full on mud colored so it should be obvious.

 

Grandmas been around long enough to know you don't go into a water filled mud pit without some extended breathers and not wait 3 weeks to do a simple lube job.

 

I'm always curious why we don't see more diff failures if this is the case, how many trucks are used to launch boats dozens of times a year? Are these people adding diff breathers or checking their fluid after every launch? I seriously doubt it.

 

I think very few people submerge their diff when launching. I’ve been launching my various boats for 50 years and never submerged the diff. Actually one time I did but I was launching from shore and not a launch ramp. Wheels went in a hole and the back of the truck was pretty deep. It was an old Ford, nothing affected that truck.

 

It's more of a possibility than a high probability. The physics of it are definitely true. The negative pressure needs to exceed the axle seals, how hot the diff is to start and the temperature it cools to are the variables that need to be just right to create enough vacuum.

 

You'll be fine till you can flush it. Let us know if you find any evidence of water when you get around to it

 

https://www.ebay.com/itm/405717442222

These come in handyfor differential fluid and transfer case oil changes .

 

Just a bit of friendly advice- if your 4wd doesn’t engage anymore in a couple weeks, check the transfer case actuator - it may have flooded from the fun and its internal parts are corroded.

 

Good way to trash the rear drums there. Clean them thoroughly asap.

 

How is that going to trash the rear drums? The mud and water will drain out and they will be fine.

 

Dirt and pebbles will make their way inside the drum and scuff up the shoes and score the drums.

 

Yeah thats a really good point. Happened to me once. Water and some of the mud will drain out, but a ton of fines and grit will be left behind. A ton. Ask me how I know

 

Good Lord, some of you talk like these trucks are made from paper mâché and will disintegrate if used for it's intended purpose! Get out there and get muddy! And if something gets mucked up because of it, then you fix it!

I pretty much just described my childhood where we slowly destroyed my FJ-55 Landcruiser during my high school years. We beat the ever-loving shit out of that vehicle on a daily basis and had the great time doing it. And when something broke from all that abuse, we fixed it and headed right back out to those muddy trails.

 

Older vehicles were much more resilient and repairable
Just sayin'

 

Is this just your opinion or can you back that statement up with some facts / data?

Just sayin"