For an even better fit, run a 1/8" pipe thread tap down into the
housing, apply grease to the tap to hold the few metal shavings it'll
|Straight 1/8NPT to 1/4 barb
|A 90 degree 1/8NPT Street Elbow
installed in the front diff.
A trip to the local hardware store revealed a whole wall full of every
conceivable type and style of fitting for 1/8" pipe thread. They
have NPT to hose barb fittings, NPT to NPT nipples, elbows of all sorts
and they all cost around $1. For the rear axle, a simple NPT to hose
barb fitting, sized for the ID of the hose you intend to use is ideal.
Up front, I found the use of a close nipple and a 45 degree elbow and a
hose barb makes a good combination.
So, what do you do with them once installed? Up front, hook up a length
of hose and terminate it at a filter on the firewall, as high up as you
can get it. In back, I first ran up to the front line and filter, but
found in cold weather that gear oil collected in any low points of the
line, and essentially plugged the vent, letting pressure build up in
the axle and forcing oil out past the seals. Then I routed it to the
rear and up onto my rear tire carrier, as pictured here.
After selling the rear bumper, I had to find a new location for the
filter. I found that if I pushed the hose up inside the rear tail light
housing, I could re-install the filter (pictured above). No drilling or
cutting required. Now that's a really cheap trick! I've found the tail
light housing seems to stay very dry, just a little dist inside. With
the filter pushed clear to the underside of the bed rail, I would have
to be in some deep water to submerge the vent line.
The following mental experiment should help see if your vent line run
is proper. Imagine you will try to fill the axle with gear oil by
pouring it into the end of the hose where you have the filter. If you
feel that you could fill the axle with oil from the end,
that is it would run downhill all the way from the filter to the axle,
then its probably OK. If there are any points in the line run where you
have a dip in the run (such as wires between power poles) then oil can
pool there. Gear oil is thick and when cold it is VERY
THICK and doesn't flow well at all. While the oil in the
axle will heat up with use and flow easily, any oil pooled in the vent
line won't heat up if its cold outside. I found when my line plugged up
with oil in cold weather, pulling the vent line off the axle and
blowing into it took a pretty strong puff or air to blow the line clear
(like blowing into a straw in a thick milk shake). That much pressure
buildup can force oil out past the axle and pinion seals.
The idea behind the breather is to place the end of the line as high as
you can get it, in a protected location where its not going to get
pelted with mud, dust and water. Some folks carry this to an extreme
and route the breather lines as well as the vehicles air intake up to a
snorkel. This, in theory, would let the rig ford water up to the point
the top of the snorkel went under water. This assumes you have EVERY
OTHER water-sensitive part of the rig waterproofed in some fashion. In
fact, there are some folks who have done all this and find that doing
so creates a secondary problem, that being that the vent is so high up,
that you get significant water pressure buildup (1/2 psi per foot of
water depth) that water gets into the axles, despite the vent. So what
then? You need to run the axle with a slight positive pressure
maintained with a small on-board air source. Certain military vehicles
are so equipped.
So where does it all stop? It all depends on how much time and work you
want to put into it and how much you need to run in water. Do as much
as you can, based on what sort of conditions you drive in. I don't
purposely drive my truck in mud or water, but if a water or mud
crossing blocks the trail and is the only way across, then I have to go
in. In many years of 4-wheeling, I've never had water get in my axles,
never had to change gear oil because it got contaminated, so I think a
simple vent like I have works good enough.
[back to the top]
About $1 per axle
After I bought my 4Runner (used) I noticed the passenger's side wheel
well liner was almost ready to fall off. I replaced some of the missing
plastic snaps and then noticed the driver's side was missing all
together. After doing my 1" body lift, it became obvious that the
liners needed to be replaced, since they no longer provided useful
protection. The liners can help reduce the amount of water and mud that
is thrown up by the front wheels into the engine bay. They won't keep
the engine totally dry, but every little bit helps.
I found a company that makes custom fit "Lift Lips"
out of heavy gauge neoprene rubber for Toyota trucks. The rubber is
over twice as thick and will not tear like the stock material. They are
supposed to fit up to 3" body lift, so I found I needed to trim a
bit of rubber around the shock towers to get mine to fit. I also found
it necessary to cut a slot for the brake line to fit through.
One thing I did notice, was that the plastic snaps supplied with the
kit fit the stock holes very loosely. I found that a #10x24 threaded
insert will fit the stock holes (a few needed a pass of a 9/32"
drill bit) nicely. I then used brass screws and washers to attach the
liners. Now, the liners are very secure, yet easily removed if needed
(like changing oil and fuel filters). Not sure if LiftLips is still in
business, but here's the last information I had:
P.O. Box 890311
Temecula, CA 92589
Lift Lips ................ $50
Threaded inserts (~30) ... 15
Brass screws/washers ..... 10
Total .................... $75
[back to the top]
I replaced the stock belt-driven fan and clutch with an electric Flex-A-Lite Black Magic Fan.
The fan is designed for drop-in replacement of the stock fan. To
install it, you remove the air intake tube and the top radiator hose.
Remove the 4 bolts holding the fan clutch to the pulley the the stock
fan shroud. The new fan brackets mount to the existing shroud mounting
holes. A rubber gasket surrounds the new shroud and seals it against
the radiator. An thermostat bulb also contacts the radiator and is
After installing the fan, I noticed its control module has some
auxiliary inputs to allow for some interesting features (you can access
the on-line installation instructions fromt eh Flex-A-Lite web page
above). I was inspired by my work on my VW pickup where I modified the
radiator fan. With the base installation, the fan will only run
when the its thermostat trips. For a reliable off-road vehicle, I felt
some functional additions were in order. (Besides I'm an electrical
engineer and can't resist tinkering with things electrical:-)
The module has an A/C input (the "C" terminal) to
turn the radiator fan on while the A/C is operating. I tapped into the
hot wire of the A/C compressor clutch for this function. This way the
fan is only operated while the compressor is actually running. This is
handy in town when stopped, there is still fresh air flowing over the
A/C evaporator coils. I did have to tweak the setting on the A/C cutoff
controller behind the glove box to keep the A/C running at idle.
There is a pair of low-current +12V inputs; one that enables automatic
operation (the "+" terminal - via the built-in adjustable
thermostat, initially, I had just tied this input to +12V). The second
input allows manual operation of the fan (this is the "M"
terminal). I simply connected these two inputs to a dash-mounted single
pole double throw (SPDT or ON-OFF-ON) switch which in turn was wired to
a fused 12V source. That is, I connected 12 volts to the center
terminal of the switch and wired the terminal that is on with the swith
UP to the "+" terminal on the fan controller and the DOWN
switch terminal to the "M" termina on the fan controller. In
the UP position, the fan is in automatic (i.e. thermostat) mode as 12
volts from the switch is connected to the "+" terminal on the
fan controller, in the center, it is off (handy for deep water
crossings - since no power is conected to either the "+" or
"M" terminal on the fan controller) and in the DOWN position,
it is in manual mode (i.e. always on since power is being sent from the
switch to the "M" terminal on the fan controller). The switch
it tucked up under the ash tray next to an indicator light (#3). Click here for a simplified wiring
diagram of the above setup.
I somehow distrust automatic things and like to know that they are
actually running. The electric fan is no exception, so I spliced a wire
to the hot side of the fan motor (this is the wire that runs from the
fan control module to the fan motor itself) and ran it to a 12V
indicator lamp that I installed next to the switch (#2). This way,
whenever the fan motor is running, the light illuminates. This is quite
useful to see if the thermostat setting is high enough to keep the fan
off during highway driving, and low enough for stop-n-go
traffic and 4WD Lo rock crawling. Also, with the A/C input (#1) you
can also see when the A/C compressor is running.
Assuming you already have the electric fan
- (mine was $200 on sale at Perf.Prod.)
SPDT toggle switch $5
12V indicator light 2
Misc wire/connectors 3
- some knowledge for electricity required.
NOTE: If you do install a switch with an OFF position, as described
above, this really means OFF, as in the fan WILL NOT COME ON, no matter
how hot the engine or coolant. Be very careful with the fan switched
off and you may want to consider some sort of guard over the switch to
prevent it from being accidentally turned off. I once had a Toyota
dealer mechanic call up and say my fan was inoperative and needed to be
replaced. He had been fiddling around (I suspect) and had turned off
the fan before starting the engine. I had purposely not labeled the fan
switch, but even so, it was "messed with".
[back to the top]
On Toyota's with electronic fuel injection (EFI) the engine control
unit (ECU) is a critical component of the truck. If it gets wet, it is
likely to stop working. The ECU box is not sealed and doing so would be
a difficult process. In my '85 4Runner, the ECU is located in the
passenger foot well, behind the small kick panel. It is placed just off
the floor, so if any water were to enter the cab via the door seals,
chances are the ECU would get wet. I decided it might be a good idea to
try to raise it up as high as possible using the existing wiring
harness. With all the HVAC ductwork and whatnot behind the dash, there
is no room to mount the ECU in there, so the next logical place was the
In picture #1, you can see the ECU fits nicely, I removed the top cover
so I could mark for the connector cutout and the mounting holes. In
picture #2, you can see the cutout for the connectors, note that the
14P connector is on the left in this picture. When the glove box is
ultimately reinstalled, this places it to the right since the 14P cable
seems to be the shortest on my truck. In picture #3, you can see the
ECU tucked inside the glove box, connectors out the bottom, and the top
of the box just protruding above the back of the glove box.
Unfortunately, you can't mount the ECU flush to the back of the glove
box, since it'll hit some of the ductwork that is just behind the box.
I left the ECU standing vertically off the bottom of the glove box and
this gives it enough clearance for the duct. FInally, in picture #4,
you can see the 3 connectors ready to plug into the ECU.
It may not seem like much, but this simple relocation raises the ECU a
full 12" (one foot!) from the factory location. I found little
loss of glove box volume with the ECU in there, still enough room for
all the "junk" I had in there before. Now this places my ECU
about as high as my engine air intake and differential breathers.
[back to the top]
In stock form, my W56 transmission and RF1A transfer case(s) are vented
through the shifter, there is no separate vent as exists on some other
Toyota gear box designs. This presents a few problems, the obvious one
is if the shifters are submerged in water, as the gear box cools and
the air inside contracts, water will be sucked inside. The second, and
less obvious problem is that gear oil smells and the venting fumes can
often enter the cabin area, this is a more common occurrence since
having dual transfer cases installed with less then perfect sealing.
So to fix this, I simply removed the shifter base off the gear box,
drilled and tapped a hole for a 1/8" NPT fitting and installed a
90 degree NPT to hose barb fitting. Then I later used some sealant
around the top of the inner rubber shifter boot to help seal it up from
water entry. Once all the vents are in place (still working on the
transfer case vents), I'll tie them all together with tee's and run a
line up forward to the firewall and install a filter for the end of the
[back to the top]
[Last updated: 06.August.2018]