Fording depth

[Ncrover725]

Today I ended up doing some Rover work after a night of light wheeling with the wife. While Checking the front diff levels I saw I took on some water at some point over the past few weeks. The fluid was a milky pastel green color. Looking back I can't think of anything that significant or for long enough duration to have allowed me to have taken on water. For planning purposes what is the depth at which you guys usually change out your fluid? I also found the milky 90wt leaking into my free wheel hubs. I think I might also have a bit of a seal problem. Thoughts.....

[yorker]

You should check the axles every time you go fording. Have you extended the axle breathers?

[Ncrover725]

I do have extended axle breathers. I guess rovers are more sensitive to offroad conditions than I thought. This is my first Series Rover am figuring out their quirks pretty quickly.

[SafeAirOne]

Anywhere oil comes out (which is almost everywhere on a Rover), water can come in when submerged.

Even without fording, vented chambers (like the axles) are subject to condensation of the water vapor contained in the air if the conditions are right, though it would take a LONG time for enough vapor to condense in the axles to turn the oil milky IMO.

Some military vehicles overcome the fording water incursion problem with valving that turns the vent lines into pressurization lines, by capping off the vents and sending a regulated 2psi of crankcase "blowby" air down the lines to the axles and gearboxes.

[disco2hse]

Umm, seriously if it's milky you *need* to change the oil before damage is done to the differentials and other parts.

Common problem and not always easy to stop:
1. Mostly the water gets in there as a result of suction. That is, when you are travelling you heat up the diffs, then when you go through a creek or puddle they cool rapidly. That results in a vacuum. This causes water to be sucked in through any weak seal.
2. Breathers are fitted onto diff housings to allow for the rapid sucking in of air, as well as to allow for the expansion of hot air. They are fitted with tubes so you can lift the end up above the offending coolant.
3. You need to make certain your breathers finish higher than the water they are submerged in. Some people run them up the door pillar I have mine finish above my air filter.
4. As the diffs heat up and cool down they can suck in dust and other particles to the tubes. As the diffs heat up oily vapours rise into the tubes and as they cool they condensate on the tube walls as an oily film. When the sucked in dust and stuff meet the condensated oil in the tubes they build up like the plaque in your arteries after too many deep fried Mars Bars. You need to check the tubes fairly regularly to make sure they are not blocked (arteries and diff breathers). Some people also fit those little air filters you get for model airplane engines onto the tube as protection against dusty crud build up.
5. The fitting on the diff can get really badly blocked with oily dust filled crud too. You won't see it unless you actually get in there and poke the holes in the tube fitting that screws onto the diff housing with a bit of wire or something. It is better to replace the tube and fitting than to try to clean it because the oily layer is still there regardless of good you think you are at cleaning it.
6. Anyway, as the diff heats up and cools down and the tube gets blocked so no more air passes through you then find that the internal pressure in the diff when it is hot is sufficient to blow your hub oil seals. That also creates a new place for water ingress. Actually I have found it is a really efficient means of pumping water into small oily places and I wonder why they don't do that instead of fracking. You know, use a Landie instead.
7. If you have the older series diff without the oil drain on the diff (just the filler hole) I would suggest you drill and tap one in, front and rear. Makes it a whole lot easier to unscrew the drain and empty it before putting new good oil in.

That's about all I can think of on the topic for now.