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How to Change Hub Oil
Y
ou can check the hub oil without removing your tires on the right front and
left rear only. But on the left front or right rear you can't because
they are aimed the wrong way. You MUST remove the tires before you can
drain any of the 4 hubs. I keep my eyes on the hubs that I can check easily
without removing the tires and if they become contaminated then I remove
the tires and change the oil in all 4 hubs. If you do any water fording
check for contamination often! I get water in mine everytime I go play in
the creek. I am told that it should be sealed and shouldn't leak but I am
told by others that the hubs always leak. So armed only with my personal
experiences, MINE ALWAYS LEAK! So my advice is to check them often, it's
easy! I don't see a recommended time to change these fluids in the
chart in my Hummer service manual, it says to check the hubs for leaks
every 3000 miles but I guess they think the oil in there will last
forever?? It won't! My advice, check it often!
click on pictures to make them bigger
I
f you have CTIS it is a little harder because there are a few extra
steps to disconnecting the air lines so the tires can be removed. First put your CTIS tire selector on the OFF position, this
disconnects the front and back airlines from each other. Then remove the
CTIS triangle shaped cover using a 5/8 or 16MM socket. Next push the air
disconnect button (silver) on the center where the air hose comes out of
the center of the wheel, the center should pop out about 1/2 inch when the
button is pressed and that tire will be isolated from the rest of the
system! NOTE: the little silver button is called a quick disconnect but it
doesn't actually physicly come apart! Don't pry it apart!!! It only
disconnects the air flow to that one tire...( Push the disconnect button
on ALL the tires before proceding to the next step!) Then to remove the
hose from the wheel use a 3/4 open end wrench to unscrew it. If you hear
alot of air hissing when your doing this then you didn't push the silver
botton on your other tires or don't have the tire selector set to off...
click on pictures to make them bigger
Y ou will need an impact
wrench to remove the tires, the threads are diffrent on the hummer from
anything else and the Lug nuts are very hard to get off without an impact
wrench, they seem tight the whole way off, unlike a normal car that spins
freely once they are loose. I wouldn't want to try and get a lug nut off
with a hand wrench, much less all 8 on one tire, much less all 32 on the
truck to do this oil change! AARGH! But the impact does make it easy,
thats why Allan here at our Car Stereo shop borrowing my impact wrench!
The lug nuts use a 7/8 inch socket. You will need to jack the vehicle up
to remove the tire, the Hummer jack is OK but a good floor jack is alot
less work or even a good HI LIFT jack would be good (every serious offroad
vehicle should have a HiLift right?) . In the pictures above you can see
Allan removing the Tire, in the second picture you can see the fill/check
bolt hole (#1) on the geared hub. When inspecting your oil level the oil
should not gush out of this hole, it should be slightly below the hole!
The oil should be a nice color, if it is whiteish or way above the fill
line your oil is probably contaminated with water! And a picture of Allan
removing the drain plug with a 5/16 hex socket (#2) . If you want to
clean really good inside the hub you can remove the side cover the plate
which is held on with 8 bolts ( the plate with the fill plug in it) but we
didn't think Allan's truck needed that much cleaning this time. The drain
plug for the hubs, like most drain plugs in the Hummer is magnetic so
examine it for metal filings and clean it off, put the drain plug back
in and fill the hub till you get to the fill hole with multipurpose gear
oil SAE80-90W (1 pint ) then put the fill plug back. Then remount the tire,
rehook the air stuff if you have CTIS. After you screw the CTIS tube nut
into the center of your wheel with your open end wrench (on all 4 wheels)
then push in the square coupling and it should re-engage and the little
silver disconnect button should pop back out. I have heard many reports
of CTIS systems leaking but so far I have not had any leaks at all in my
CTIS system.
W
hile Allan was under there he drained and replaced his oil in his Axles
(differentials) it uses the same gear oil as the hubs and is easy to do!
The drain is on the bottom and is a 3/8 inch hex and they hold 2 quarts of
gear oil.
Last minute
update!
Scott Weiser made some last minute points
just as I was going to upload this to Bob!
I don't want to redo the
whole stinkin page so I will just throw Scott's text in here at the bottom!
It is important stuff!!! (I knew I would forget something!)
When you change the hub oil, you should check the spindles for tightness
to see if the spindle nut has loosened. To do this, with the wheel off,
use a pry bar over the drag link and under the spindle flange edge and try
to wiggle the spindle up and down or in and out. There should be no
detectible play in the spindle. Also look for "weeping" in the spindle
seals and check your vent tubes for damage/crimping, along with checking
the torque on your upper and lower ball-joint bolts. Just a note, it's a
good idea to put the bolts into the balljoints from the *bottom*, with the
nuts on top, so you can see if they have loosened up during pre-trip
inspections. My first trip to Moab, one vehicle was disabled because the
upper ball joint on the right rear wheel ripped out of the upper control
arm, which was caused by a missing and several loose bolts, allowing it to
"slop" about.
Thanks to Allan Madar for letting me take his picture while working on
his Hummer with my tools.
Thanks to Micheal Selig for suggestions writing this tutorial
Thanks to Jack Rickard for telling me how to do the big/small pictures.
Thanks to Scott Weiser for waiting 'til the last minute to let me know
all the stuff I forgot! :-)
Thanks to Bob and ALL the HML list members for everything!
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