Possible water in the rear diff

[HenriSteyn]

Guys Ifound myself in my Paj in a mud hole on the recent NKZN trip (story for the trip report).

Right rear wheel was completely submerged.

Should I change the rear diff oil as a precaution due to a possible water ingress?

Cheers

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[KurtG]

It won’t hurt and is relatively easy to do but unless the diff itself was submerged I don’t know if water would get in from the side shafts? Maybe a non-greenlaner can comment

[HenriSteyn]

Thanks Kurt.

Not sure how high the breather is, if i am going to crawl under there i may as well do it.

Cheers

[CornellMans]

If you suspect that there might we water in there, rather change to be safe I'd say.

[Apocalypse]

Provided it's in reasonably good condition, there is no way water can pass the seals on the half shafts and get into the diff.

Water gets into Diffs (and gearboxes and T/Cases) through a bad diff breather - As the diff heats up it pushes out air (expansion of gases etc) through the breather.

When you go into water you obviously suddenly drop the temperature, which causes the unit to pull air back in as the gases contract. If the vent is under the water at that point, it will pull in water instead of air.

BUT manufacturers aren't entirely dumb, so they fit either a pipe to a higher point in the engine bay, or a one way valve to prevent contaminants from getting into the diff.

A poorly maintained vehicle will mean that some chop has failed to re-install the one way valve or breather pipe during some kind of maintenance at some point.

Check and see if it's present.

It if's not , and it looks like the water rose over the vent, then you might have water inside it.

If the water got over the rear diff vent, I can't imagine that it didn't get over the TC vent, G/box vent and front diff vent too.

Best to do is to remove the filler plug, put your finger in, if it looks like chocolate milkshake, it's got water in for sure.

I can't remember if the Mitsus have a diff drain plug - if they don't you'll need to remove the diff to drain it, or the diff cover. If it's got one, great, easy job, if not... more of a story.

Transmission oils should be replaced periodically anyway....

[HenriSteyn]

Thanks for the feedback Apoc.

It stood deep at the arse for some time thus my thoughts that it may only be the rear diff.

[Apocalypse]

Thanks for the feedback Apoc.

It stood deep at the arse for some time thus my thoughts that it may only be the rear diff.

I guess if one standing as if launching a boat then of course the rear diff would be the only thing under!

I was thinking you'd driven through an obstacle and got the whole lot in deep!

[BushWacker]

.... maybe top it up a bit, and if streamy creamy
coffee coloured stuff flows out get suspicious ...

[BushWacker]

... if it was high-tide at Kosi Bay and you were retreating back from the mouth on the skirting road past the fish traps area when it happened ... I also dropped a bit hastily into that deep hole in what looked like shallow water.
A bore of water shot up and I heard it hit the bonnet underside .
Engine went off & when I restarted it repeatedly cut out again on any accelleration
Theory is water got onto oil pressure sensor terminal and each time the thing fed the ECU a bad reading so the ECU repeatedly cut the motor ... later evapo-dried from block/ manifold heat and so, after a while, I drove off .
My next project is to prevent such wet shorting of the
Pressure Sensor and Crank Angle Sensor terminals etc though Ive never experienced the problem when deep wading.

[david bfreesani]

I have found traces of water in oil, long before you can see milkshake. I do the crackle test. Take a sample of oil, and set it alight in a teaspoon. If it crackles, you have traces of water in the oil. You will be amazed at how little water you can detect in the oil with this method. I tested it with old engine oil, and just dipped my hand in a bucket of water and flicked it off my fingers over the open drum. Gave it a stir, and did the test. The before and after crackle test picked up the water. I check every now and then, just to make sure. I go through the car, take my five samples, and go do the burn test. So far I have never found water, even after the drowning where the car stood dash deep in the water for nearly 10 minutes.

[HenriSteyn]

Since the original post i have crawled under to remove the towbar (This story to be covered under a NKZN trip).

While upside down i had a look at the breather. It exits out the top of the diff and enters into a channel in the bodywork above the diff. This is much higher than the Paj was in the water.

I am at ease....

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[BushWacker]

... if it was high-tide at Kosi Bay and you were retreating back from the mouth on the skirting road past the fish traps area when it happened ... I also dropped a bit hastily into that deep hole in what looked like shallow water.
A bore of water shot up and I heard it hit the bonnet underside .
Engine went off & when I restarted it repeatedly cut out again on any accelleration

Theory is water got onto oil pressure sensor terminal and each time the thing fed the ECU a bad reading so the ECU repeatedly cut the motor ... later evapo-dried from block/ manifold heat and so, after a while, I drove off .
My next project is to prevent such wet shorting of the
Pressure Sensor and Crank Angle Sensor terminals etc though Ive never experienced the problem when deep wading.

... been thinking : would good squirt/spray of WD40 work to solve any recurrence of this ... heard folk oft use it for wet Distributors/spark plugs ... ?

[BushWacker]

... if it was high-tide at Kosi Bay and you were retreating back from the mouth on the skirting road past the fish traps area when it happened ... I also dropped a bit hastily into that deep hole in what looked like shallow water.
A bore of water shot up and I heard it hit the bonnet underside .
Engine went off & when I restarted it repeatedly cut out again on any accelleration
Theory is water got onto oil pressure sensor terminal and each time the thing fed the ECU a bad reading so the ECU repeatedly cut the motor ... later evapo-dried from block/ manifold heat and so, after a while, I drove off .
My next project is to prevent such wet shorting of the
Pressure Sensor and Crank Angle Sensor terminals etc though Ive never experienced the problem when deep wading.

... would good squirt/spray of WD40 work if this happens again ... does the stuff work well on distributors spark leads etc ?

[Mad Manny]

You really should put your story in it's own Thread.
This Thread is Possible water in rear diff.

Your story is about Definite water io ECU/Electronic components.

Different topics...

[grips]

I am with Appoc that water does not get by the seals easily. However in depends on the rear wheal bearing setup. In some setups you have a side shaft inner seal, then a pocket or space for the bearing then a side shaft outer seal and hub flange. In this case the bearings are not lubricated by oil from the differential but by grease packet into the pocket. I have seen water present in the grease on numerous accounts.

Make sure what the setup on the Pajero is and have it checked.