Installation of On Board Air system


Q. What is an on board air system anyway??

A. It's an air tank or copmpressor system mounted or secured in a vehicle that provides air for reinflating tires or running air tools. Tank systems are almost always CO2 tanks, which are portable. Compressor systems are either electric powered or engine driven.

Where can I get a similar On Board Air system? Here: (Kilby Enterprises) or any of their dealers

Many of the photos below show detail of the various pieces and parts.
Showing them helps to understand how they attach and may simplify your project.

I chose to duplicate the Kilby style system using an engine driven York compressor that I had from a previous onboard air system. The system I had was probably the prioneer of engine driven York systems - a company name Terold Industries / Ready Air, which did business back in the 80's and 90's. I used the system mounted on a 1979 full size GMC Jimmy (same as a Blazer.)

To complete the project, I bought the bracket kit and several accessories from Kilby Enterprises, which included the new serpentine belt and hardware and also ordered the oil return line. Other major purchases included the serpentine pully/clutch asembly and the coalescing filter. An assortment of brass fittings were obtained at the local hardware store.

Surgery on the Jeep begins by loading up the surgeon's table with the proper tools - notice the hammer too...
I started by removing the v-belt clutch and pulley assembly

I installed the appropriate serpentine pully/clutch assembly.

Here's the pile o' parts. Belt, hardware, dipstick, bracket and oil return hose and fittings

The bracket gets mounted in place of the alternator, and the alternator gets attached below the bracket. There's an idler pulley attached to the alternator bracket that gets removed and reused.

I later removed the air box to gain easier access to the side of the compressor when I was tensioning the belt. Might as well remove the air box now.

Notice how the two A/C line are routed - this is the factory routing. The aluminum hard lines need to be carefully spread apart from each other so the rubber lines don't hit the compressor of the pulley. Further along in the write up you will see the spread of the hard lines.


This photo shows the compressor siting on the bracket, with the two tensioning screws in place.

My compressor has a drain petcock and an oil fill hose which sort of get in the way of things.

Alternator is bolted up here as well.


This shows the compressor, output hose, intake fitting minus an intake filter.

Notice the spread between the two A/C hard lines.

Compressor clutch wiring has been routed
and protected with split loom.

Original hose already had a check valve in it, so I left it in place and connected new hose to continue on to the doo-dads mounted on the grill support bar.

After the compressor was mounted, I worked on hose routing.

Installing all of the misc. doo-dads was the most time consuming part of the project - the trick was getting everything to fit and not be in the way of other components already under the hood.

I made about 4 trips to the hardware store to buy and return, and buy, and return some more brass fittings and couplers to connect everything.


Most of the hose I used was left over pieces from the Ready Air system I had on the Jimmy.

Here you can see the air manifold mounted to the grill support bar using adel clamps.

Hose test fit. The hose above the manifold runs down the driver's side of the radiator and out to the bumper where I have a quick disconnect air fitting. You can also see the coalescing filter dangling free just behind the master cylinder.

Output hose from compressor goes along the firewall and connects to the coalescing filter

Hose secured with adel clamps and 1/4
stainless bolts with nylock nuts.

I left the hardware loose until all of the doo-dads
and hoses were positioned in their final locations.


Manifold with (l to r):

Pressure relief valve, elbow for air line to air solenoid, pressure switch, plug in a non used hole.

Back side of manifold. Here you see the gray oil return line attached to a valve at the bottom of the coalescing filter and the pressure switch on the manifold.
Air solenoid for air horn. I later removed the
solenoid after it got stuck in the OPEN position.

Big picture view of all the doo-dads, including an air regulator, which really was overkill.

Don't use that clear vinyl tubing like I did between the manifold and air solenoid, it can't withstand the pressure. I replaced it with some pressure rated hose. If doing something similar, be sure to use clamps or the proper gripper type fitting available from Kilby.

Output hose from pressure regulator goes
down along side the radiator.
Check valve and fittings covered in split loom