How deep should we be able to go in our trucks before we have to worry about water getting into the differentials?

 

Rule of thumb is bottom of spindle/axle. If the diffs are hot as well as the wheel bearings the sudden cold water hitting the will cause it to suck it into the diff.

With that said if you reroute the breather tube to higher up, and change you fluids after hitting deep water (bottom of bed ) you should be fine.

I used change mine in my 1980 mud bogging truck after every event. Drove it until 2007 when I sold it. No problems

 

10-4 thanks for the info.. I didn't get too deep over in Texas last week but did go through water over the running boards. I'm not lifted, just leveled.

To check, don't I take the fill bolt/plug out on the front of the rear diff. then stick my finger in to see if its milky or not?

 

Our diff breathers are routed up and mounted under the bed and that's plenty high

 

Gear lube is cheap I would just replace it. I use Luke's oil. Have not done a new one so I am not sure of the weight.

 

+1 - Why take the chance. Just replace it.

 

+2

I've been a Jeep guy the last 10 years or so, changing out the diff fluid is something you can do at home in your driveway for about $50 in oil and sealant and maybe an hour if you clean the diffs before you seal and refill.