[Scorpyon]

Hi all,
I finally got to checking the oil levels in my diffs and they are both thick and milky white. Water logged?

I'm getting the parts (all diff seals) on Friday. I was wondering if it's "ok" to use the ATV anyway but just to plow the driveway. Getting lots of snow right now.

Some people get water in their diffs when on the trail and still ride them back home so I was thinking it should be ok to plow the driveway for 15 to 20 minutes.

What do you guys think?

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[dezz]

Getting it wet on a trail and riding it home is completely different than what you got.

If you want to use it at home, you still got to change the gear oil. The water that's mixed in your existing oil now can potentially freeze. It will make the oil/water mixture a sludge at a minimum....and this can lead to metal on metal contact and differential damage.
For the sake of some time flushing the diffs and filling with clean gear oil.....it's well worth it to save the cost and time of rebuilding a differential.
At the very least, do a drain and fill. This you can get away with for the weekend as this will get the bulk of the water out of the diffs.

 

[Scorpyon]

Thanks Dezz! Wasn't thinking about it that way. I'll drain them and refill with fresh oil. That'll probably help to "clean" the diff and I'll flush it after plowing. Then change all seals on Friday.

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[dezz]

For a little extra cleaning, flush the diffs with some diesel. I do this when flushing diffs in colder temps as usually the "milky oil" is very thick. The diesel acts as a solvent to thin the milk and clean at the same time.

 

[Fireman2]

Real simple to drain and refill, too expensive alternative not to.

 

[Scorpyon]

Does the gear oil absolutely need to be hypoid oil for this application (for rinsing/flushing driving around for 15-20 min)?

It will be 80W extreme pressure GL4 though.

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[thrashingcows]

Do you have any used engine oil kicking around? I bought an older Case 1845C skid steer and had lots of water in the chain cases, and planetary assemblies. I used most of my old 15W40 engine oil I save from servicing my Cummins 12V motor to flush the systems multiple times. If it were me I would use the old engine oil to refill the diffs, then plow the driveway, then while still warm from plowing drain and fill with fresh gear oil.

 

[dezz]

Do you have any used engine oil kicking around? I bought an older Case 1845C skid steer and had lots of water in the chain cases, and planetary assemblies. I used most of my old 15W40 engine oil I save from servicing my Cummins 12V motor to flush the systems multiple times. If it were me I would use the old engine oil to refill the diffs, then plow the driveway, then while still warm from plowing drain and fill with fresh gear oil.

While I see where your going with this, you should never run engine oil in a hypoid style differential and actually use the diff under load. Using it as a cleaner is fine, like I do with diesel, but you do it with no load on the diff. I always do it with the bike on jack stands.

Engine oil does not have anti-shearing additives. These anti-shearing additives are crucial in a hypoid style gears so that you do not have metal on metal contact. This is due to how hypoid gears operate....they scissor together when meshing. This scissor action creates a high shear load, thus requiring anti-shearing agents to prevent gear face wear.

Doing this in a chain case is perfectly fine, but it should not be done in hypoid style geared differentials.

 

[dezz]

Does the gear oil absolutely need to be hypoid oil for this application (for rinsing/flushing driving around for 15-20 min)?

It will be 80W extreme pressure GL4 though.

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If your going to put the diff under load (operation), then I would not use anything but a hypoid gear oil (GL4 and GL5 rating).

 

[Scorpyon]

I did a quick search and apparently any High Pressure GL5 gear oil is compatible with hypoid gears. That's what I have lying around and that's what I used. Plowed the driveway last night then drained both diffs. I will refill them again tonight, plow again (we got a lot of snow) and re-drain. Then the diffs should be nicely flushed, ready for new seals and fresh gear oil.

Thanks for the advice! I'll be replacing the seals this weekend so if I run into any snags, I'll be coming back for more help.

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[dezz]

I did a quick search and apparently any High Pressure GL5 gear oil is compatible with hypoid gears. That's what I have lying around and that's what I used. Plowed the driveway last night then drained both diffs. I will refill them again tonight, plow again (we got a lot of snow) and re-drain. Then the diffs should be nicely flushed, ready for new seals and fresh gear oil.

Thanks for the advice! I'll be replacing the seals this weekend so if I run into any snags, I'll be coming back for more help.

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The GL# is a rating system for gear oils. It goes from GL1 to GL5. There used to be rating higher than GL5, and it was mostly used in racing applications. But that rating had been abolished for over a decade now.
GL4 or GL5 means it is meant for hypoid gears. Many call it hypoid gear oil, but the oil is not actually called hypoid. Hypoid just means the style of gears it is meant for.
The biggest difference between GL4 and GL5 rating is percentage of anti-shearing agents. GL5 has a higher percentage of anti-shearing agents, which allows it to be used in extreme uses. GL5 is perfect to use in place of GL4. You just can't go the other way

 

[Scoundrel]

Just looked through this thread.
Always wondered how to really get all of the old crap out of a gearbox, diff, etc.

So what does it look like to flush it with diesel? Would I, for example:

1. Jack the thing up and put it on stands so it's REALLY stable.
2. Drain it, and refill it with diesel.
3. (And this is the part I am unsure about) Fire it up and spin the wheels a lot to really splash that diesel around?
4. Drain the diesel.
5. Fill it with the proper fluid.

Anything extra to do after draining the diesel? Extra fill and drain of the regular fluid, to flush out the diesel?

 

[Scorpyon]

I'm no expert but I wouldn't run it with only deisel in it. Maybe 1/3 deisel 2/3 gear oil.

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[Scoundrel]

I'm no expert but I wouldn't run it with only deisel in it. Maybe 1/3 deisel 2/3 gear oil.

I was only thinking while still on stands. No load.

 

[Scorpyon]

I don't know... Maybe dezz can chime in on this one. In my opinion, deisel is a bit oily but those gears would be sort of grinding together with hardly any lubrification.

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[thrashingcows]

I think a 50/50 mix of gear and diesel would be a good, and as long as you don't run it for too long, and it's off the floor with no load. I would let it drain over night to allow most, if not all the mix to drain out, then fill with fresh gear oil. Dezz seems like a very knowledgeable individual...hope he chimes in with a his recommended procedure....:thumbsup

 

[dezz]

I have always just used diesel alone.
I have the atv jacked up, with the diff full of diesel (or whatever solvent based cleaner you choose), I then just turn the wheels with hands for a minute or 2. Then drain it. You do not need to run start it. But you can if you like.

If you want to do a mixture of gear oil and whatever, that is perfectly fine too. You could even use regular engine oil if you like, just as long as your doing it on Jacks (no load) and slow (crawl speed).

Doing the rear wheels is easy with a 2wd/4wd selectable system. Doing the front requires you to turn both tires at the same time to get the crown gear turning (by hand).
Full time 4wd bikes require the complete bike be jacked up in order to do any diff, and is alot harder to do by hand. In this case, I'll usually start it and use the engine.

 

[Scoundrel]

Yeah, I wouldn't want to put load on them or spin them fast when full of diesel for flushing, but didn't see the harm in spinning them moderately with no load.
I see how that would be a problem with the crown gear in a diff.