Air Supply for Tires
and Tools
Tapping into the Range Rover Air
Suspension for Compressed Air
Introduction
On lesser off-road vehicles it is necesary to obtain and instal a
separate air compressor and air tank in order to have air on tap for
trail duties such as airing up tires after you have aired them down or
repaired a flat -- or even to pump up a leaking tire temporarily to get
you to the nearest service station.
Fortunately all late model Range Rovers come with a built-in air
system, and it only remains or the owner to tap into it. Doing so also
makes it easy to plug in a pressure gauge to help diagnose any faults
in the electronic air suspension.
My First Installation
Installation of Air Line
The picture at the top of this page illustrates my initial air supply
system on my 4.0SE. First, the drain plug on the air tank was removed
(do it slowly to allow the air to escape before the threads are
disengaged, and don't put your head in line with the plug in case it
flies out). The drain plug was then drilled and tapped 1/8" NPT
(outside the US you might wish to use whatever metric thread is
convenient). This allowed a 1/8" nipple and elbow to be installed in
the plug. I managed to get the elbow to point slightly upwards so
anything attached to it would not hang down below the air tank.
(See photo at top right -- view
looking forward)
The elbow was connected directly to a 1/8" to 1/4" adapter, since in
the US most standard automotive and workshop air hoses and fittings use
this size. To the adapter I screwed a 25 ft flexible coiled air hose
and ran it over the top of the chassis rail, then forward using the
space between the chassis and the bodywork (see photo). The coiled hose
fitted neatly into this space and held itself there due to the lip on
the inside of the lower bodywork sill.
On the other end of the flexible air line, I attached a standard
quick-connect fitting so that any kind of shop air tool could be
attached in seconds when needed. In storage mode, the quick-connect
fitting was wrapped in a plastic bag to keep dust out and poked into a
hole in the side of the chassis rail. To use it, all I had to do was
pull the quick-connect hose fitting out of the chassis rail and pull
on the hose, which would neatly unravel and extend to its full length.
Restoring it to its stowage position was equally easy.
An easier way to do this might be to use fittings that directly screw
into the air tank. Andy Cunningham reports the metric drain plug
size to
be 20x1.5mm on the P38/4.0/4.6. A blurb I came across from a company
called RPM Off-road Motorsports indicates the plug on the outlet of the
tank is 1/2
inch NPT. There is an unused plug on the center of the front of the 4.0
tank, and I am wondering if this is a 1/2 inch NPT as well. If
anyone has more information on the thread sizes used in
the Range Rover air system please email me.
The System in Use
I found it very convenient being able quickly to attach a tire
inflator, compressed air nozzle and other devices to the ready-to-hand
source of compressed air. Friends are always amazed when you
nonchalantly reach under the door sill, pull out an air hose and give
their tire a shot of air. Another advantage of the system was
being able easily to attach a pressure gauge, for diagnosis of the EAS
system. Even the dealer took advantage of this upon occasion. I did
note try running air tools off the system, but there is no reason why
this would not be possible in short bursts. (For serious air tool use,
a more powerful source of air such as an engine driven compressor would
be best).
The one shortcoming I encountered was that in muddy conditions the mud
kicked up behind the front wheel tended to attach itself to the neatly
coiled and stowed air hose, adding enough weight to it to make it droop
down below the body sill. On one very muddy winter trip the hose fell
right down and was run over by the rear tire, breaking the hose and
causing all the air to escape from the tank. I decided to devise
an improved system for the future -- also preferably one that did
not require bending down to access the hose!
Other Approaches -- Work in Progress
I have often considered an alternative approach, namely to tap into the
air system at the
valve block and instal a quick-connect fitting on the adjacent left
front fender. I did not get around to this on my 4.0, but other owners
have now done their own air systems. See the following:
Jim Haver installed an excellent tap into the air system under the hood
with a built in air pressure gauge; see this link.
Caveats:
Be sure whatever air fittings you use can withstand 150 psi (10 bar) as
some standard shop air fittings cannot.
Also, be aware of the possible confusing effects these air supply mods
might have on the air suspension ECU. James Howard has been
contemplating a similar approach for his 93 Range
Rover, but he has been afraid to because he read in the shop
manual
that if the compressor runs for too long a time, the computer thinks
there is a leak in the system and goes into fault mode. I have never
run into this problem
but it is worth bearing in mind if you are doing an extended airing up
job!
