To rebuild or not?

[bbyrnes1]

Hey guys,
I'm in the midst of a moral dilemma. I have a 9 inch open rearend that does NOT leak or make funny sounds. I sucked as much of the fluid out of the fill hole as I could, and it was disgusting diarrhea brown colored.

I don't want to open up a can of worms by taking the axles out and removing the carrier then having to replace seals that are currently sealing. However I'm not thrilled with the idea of having new fresh fluid mixing in with the residual old crap still in there.

Any thoughts on buying some cheap new oil, running it for a few hundred miles, then sucking it out and then adding in some good stuff? BTW I'm planing on running 75W-90.

Thanks,
Brandon

[Kurt Combs]

Sounds like you have water in the gear oil. I'm not sure how much damage the water will cause, but I would sure minimize potential damage to gears and bearings. I would try running it a few miles and changing the oil again and see how it looks.

[mrtleavitt]

I would do exactly as you posted bbyrnes1. If everything seemed to be fine with that old crap oil in it then throw in some fresh stuff, run it, then change it again if you want. Just think about engines and trannys- when you change the oil there is usually a good amount of old oil that doesn't come out and just mixes in with the new oil.

[colnago]

I would get a new gasket for the cover, then pop it off and evaluate the fluid that you still have inside. A gasket plus sealer can't be more than twenty bucks, which is less than a new round of gear oil. So now you have three different suggestions! Great!

Just my two cents,

Joseph

[papabug71]

If it isin't acting crazy no need to rebuild it. Run it with new oil for a little while, drain it & refill. Might even give it a 3rd drain & refill just to make sure you got all the poop out.

[bbyrnes1]

Thank for the replies guys.
I spent some more time on it yesterday and used a smaller diameter hose on my pump and was able to angle it towards the center of the housing. I got a surpring amount more out than I did the day before. I believe I was only sucking it out of the carrier, which isn't as low as the housing.

Unfortunately I wasn't pumping it into anything I could measure from, but from how much I pumped out I bet I got every bit of 2.5 quarts, which I believe is about the capacity of one of these. Whatever residual left in there is probably nothing more than the film left on the surfaces of everything. As mrtleavitt said, whenever you change the fluid in anything else there's always going to be some residual left over. You don't take the engine apart to change the oil . So I feel comfortable just adding in my fancy oil and letting it ride. I appreciate the input.

Brandon

[bbyrnes1]

Also, is 75W-90 a suitable weight oil to use? I've read to use anything from that to 85W-140.

[Art]

75W90 is fine, especially during winter months. Heavy loads in the summer is when you need heavier weight oil.

Check your drained fluid to see if it has water in it. If you see water settled out of that fluid, lots of water got into the axle. If you are unsure, you can test it by putting a drop on a hot surface (250-300degF). A hot exhaust manifold probably would work (engine off of course). If it sizzles or crackles, it has water mixed in it. Water mixed with oil makes it cloudy and sludge, lots of water mixed in looks like a chocolate shake.

If it the oil has water in it, I would drill a 11/32" hole in the bottom of the housing far enough away from the weld seam and off to one side. Then you can let all the oil/water oil drain out. Then tap the hole for a 1/8" NPT hex socket head pipe plug and now you have a nice convenient drain that is flush mounted. I have done this on several vehicles that did not have an easy way to drain the axle.

I would give it several (3+) oil changes, especially when the fluid is warm after a longer drive.