aw4 filter change

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the other day, i got under my jeep to check the steering.
while i was under there, i noticed my transmission pan was leaking.
i took the jeep to the car wash and sprayed the pan clean.
lots of road grime and dirt had accumulated from the leaking fluid.

the trans pan is the rectangle with ribbing in the photo below.
you can see where the leaking fluid has 'cleaned' the pan:


fixing the leak meant installing a new trans pan gasket.
this was the perfect opportunity to put in a new filter, too.
with the pan off to change the gasket, i had easy access to the filter.

below i describe this process.
it was well worth the effort!
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STEP 1.)
drain the fluid
the aw4 transmission pan holds 4 liters of ATF - dextron III.
(the entire transmission holds closer to 9 liters, i only changed the pan volume)

the drain plug is on the back of the pan:



the transmission cross member is right in the way of the drain flow.
i used this small funnel to redirect the flow away from the x-member:


after draining the fluid, i re-installed the drain plug.
not all fluid drains from the pan due to recesses and ribbing.

this container holds my used fluids, in this case trans fluid:
i go to my local auto parts store to dispose of used fluids properly.

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STEP 2.)
remove the bolts holding the pan to the transmission
they should be torqued to 60 ft/lbs, but mine came off very easily.
(perhaps tightening these would have stopped my leak!)

i removed the bolts along the sides of the transmission pan:

the ends of the pan are impeded by the exhaust and the x-member.
my wrench and extension wouldn't align strait on some of the bolts.

i used a swivel to redirect my extension to clear the exhaust:


the swivel was handy in the rear, too, where the x-member is in the way:


a single bolt was blocked in a way even my swivel wouldn't fix.
the exhaust hanger is directly impeding this bolt:


i used a ratchet strap to pull the exhaust aside temporarily.
this allowed me enough clearance to remove the bolt using the swivel:



reinforcements for step 3 - chisels, rubber mallet, glass of water:

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STEP 3.)
break trans pan seal
the factory uses red RTV sealant as a gasket.
this sealant gets hot and bakes on as it adheres to the trans and pan.
i used a rubber mallet to tap around the pan to loosen the sealant.


a sharp flat chisel helped to carefully pry the pan off at the corner:


my first look inside my jeep's aw4 transmission:


now, the dipstick tube (at bottom right) is all that holds the pan up:

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STEP 4.)
drain remaining fluid
as you can see, my transmission fluid was quite dark.
transmission fluid is supposed to be a translucent reddish pink.
good thing i will be cycling in some fresh fluid!

quite a bit of fluid stays in the pan after the initial drain:


i unscrewed the drain plug once again.
tilting the pan allowed me to drain the remaining fluid:

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STEP 5.)
remove transmission pan from the jeep
i worked the dipstick tube and trans pan out from under the jeep.

the tube will remain connected to the pan for the entire procedure:


the dipstick tube connects the trans pan to the engine compartment.
this is how you check the transmission fluid level and add lubricant.
i unbolted the dipstick tube from the engine compartment.

the dipstick is accessed in the engine compartment and ends in the pan:


there are 2 small magnets in the bottom of the transmission pan.
these are used to accumulate small metallic particles.
as transmissions break in, metallic bits naturally wear off.
i was pleased to see that i had a normal amount of wear.


pan magnets in pan removed from the jeep


left is clean, magnet on right illustrates accumulated metal particles:


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STEP 6.)
prep pan for new gasket
i scraped all of the red RTV sealant from the pan.
i used a bit of parts cleaner and emery cloth on seal surfaces.
(being VERY careful, as parts cleaner should not be in a transmission!)


here you can see the long dipstick tube still attached to the pan:


trans pan all prepped for the new gasket:

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STEP 7.)
out with the old, in with the new

the filter is held in place with 4 13mm bolts.


the transmission filter is the dark gray rectangle:


trans filter removed:


old filter is dark gray, new filter is light gray:


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STEP 8.)
re-install transmission pan

its easy from here out

test-fitting the new gasket i got from NAPA


the cleaned magnets are put back in the pan for re-installation.
note the dipstick tube going to the engine compartment:


feeding the dipstick tube back up to the engine compartment


the gasket held the pan bolts in place for me.
i put one bolt on each side to get it held in place at first.
i used a punch to align the holes in the gasket for the remaining bolts.

one 'prep' bolt on the far left, one near the right side:


i torqued the bolts to 60 INCH/lbs


final touch - add 4 liters of ATF - dextron III

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Appendix A.)
tools used:


* shop light
* pocket knife
* ratchet strap
* chisel - wide
* chisel - narrow
* emery cloth
* rubber mallet
* shop gloves
* torque wrench
* 3/8 ratchet
* 3/8 extension
* 13 mm socket
* swivel
* 1/4 ratchet
* 1/4 extension
* small funnel
* long funnel
* flashlight
* keys
* parts cleaner
* punch