Pressurized wheel housing in the front. Normal? Bad?

todds112 · Post by **todds112** » Fri Apr 20, 2007 8:32 pm

Went to check and change out the gear oil in the front today. The passenger one was a bit low to due to a seepage around the sphere itself. I drained it and replaced with the Sta-Lube from NAPA. Even bought the nifty little pump. Anyway went to the driver side and when I took out the top (fill) plug, it made a "pooft" noise and literally sprayed oil out of it. Well, more of a burst of oil.

I know I read about pressurized wheel housing, but can't remember in what context. Is this normal? Is there a breather that might be bad/clogged? The truck was warmed up and had been driven several miles right before I did the change.

BTW the Sta-Lube 85w90 is rated as GL4, GL5, so I'm going to replace whats in the tranny with it too. I'll eventually replace everything with it then I only need to keep one fluid on hand (besides engine oil).

The pump is pretty cool, but I still made a total mess. Man that stuff is hard to clean up.

mjnims · Post by **mjnims** » Fri Apr 20, 2007 8:46 pm

While you are at it you should change all the hydraulic fluids in the brake and locker lines. If I remember correctly it took me almost 4 quarts to get clean fluid throughout. I have had no issues with the lockers engaging and disengaging with my 712 (which I have changed) but my 710's lockers used to hang up until I changed the fluids and cleaned out the slave cylinders. I am not sure the fluids were ever changed based on the looks of them in both trucks.

Jim LaGuardia · Post by **Jim LaGuardia** » Fri Apr 20, 2007 8:52 pm

Pressure is ok, it means the system is sealed good.
As for the gear oil, use G-L 4 only, not multi use gear oil in the trans.

todds112 · Post by **todds112** » Sat Apr 21, 2007 1:42 am

From another thread:

NAPA tells me that the Sta-Lube (SL24239) is an 85w90. Will that work in the transmission (gearbox) without any problems, or it this too heavy a grade?

Reply was:

That weight will be fine.

Now I'm totally confused. It can't be this hard to just find lube to put in the dang tranny, is it?

Kiwibru · Post by **Kiwibru** » Sun Apr 22, 2007 12:50 am

Finding a straight GL-4 can be hard. That is why many use the Redline product (for tranny) as it is the best of both worlds..synthetic yet still a GL-4. I used a Chevron Delo 75-80W in the other gear locations that covers both GL-4, 5 and I have not had a problem.

undysworld · Post by **undysworld** » Sun Apr 22, 2007 11:58 am

When draining the oil from a wheel asssembl, I was told to open the upper plug first. This was to prevent that pressure you mention from blowing oil out the drain plug, to avoid the mess. Apparently some pressure in there is normal, and as was suggested above, may be desirable.
I use large pieces of cardboard to lay on the floor before I do any gear lube related work. That way, hopefully, all the mess lands on the cardboard and I can easily get it off the floor. It starts bonfires really well, too, which is nice.
Paul

pinzinator · Post by **pinzinator** » Sun Apr 22, 2007 12:38 pm

Jim, is GL-4 synthetic OK for the transfer case and differentials, too?

pcolette · Post by **pcolette** » Tue Apr 24, 2007 5:58 pm

Todd,

The Stalube SL24239 that I picked up from NAPA is a 85W90 but is GL4 only, no mention of GL5 on the container. Could be old stock as the NAPA guy said he doesn't remember ever selling any before. Anyway, I'm going to give it a try in the gearbox. Got to get that pump first though.

Paul

todds112 · Post by **todds112** » Tue Apr 24, 2007 8:48 pm

pcolette wrote:Todd,

The Stalube SL24239 that I picked up from NAPA is a 85W90 but is GL4 only, no mention of GL5 on the container. Could be old stock as the NAPA guy said he doesn't remember ever selling any before. Anyway, I'm going to give it a try in the gearbox. Got to get that pump first though.

Paul

The bottle did say something about "New Formulation" or something. It's the purple label. On the back is had the SAE standards, etc. Said it meets GL4 and GL5.

The pump is only a couple bucks and works pretty darn good.

I still made a mess.

Roman · Post by **Roman** » Wed Apr 25, 2007 7:03 am

Usual advice is to take a ride before changing oil. This way the oil gets warm. Being less viscous, the oil drains out better.
The air inside the housing also warms up and hence the higher pressure.
My old Range rover had venting valves on the axle housings (preventing mud, but sucked in water during wading).
Discovery had tubes from the axles to the high place hidden inside the body.
For pinzgauer it seems that there is no ventings, therefore the pressure build-up inside the drive housings (and no water ingress during wading).
Interesting note is that most amphibian vehicles are using pressurisation of the axle housings during floating, to prevent water entering the mechanical components.

Maybe someone knows better.

Roman