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Off Road Only Air System

Off Road Only Air System

Part #:

The biggest problems with installing an OBA system is finding a location to mount all of the parts for it, and actually assembling all the individual parts to make it up. We face these things with the limited space in a Jeep thrown in on top of it. The most mounting area we have is under the hood, where these components are subjected to a lot of heat from the engine. I spent some time researching the individual parts that I wanted to use to make this system up and it pretty much came down to ordering a bunch of parts from Kilby's, or getting the Air Kit from Off Road Only. I opted for the kit from Off Road Only for several reasons, the heavy duty braided compressor discharge hose, and the Norgren pressure regulator and Oil filter (with automatic oil return).

The major parts of the ORO Air system are:
Tank (1 gallon/ mine)
Norgren Pressure regulator
Norgren Oil Filter (with Automatic Oil Return)
Pressure Switch (electronic)
Safety Valve
Compressor Discharge Hose
Air Lines

Optional Items:
In Cab Air Pressure Gauge
(2) Air Chucks.

Additional Parts:
Teflon Tape
(4) 1/4-20x3/4" Stainless Bolts
(8) 1/4" Stainless flat washers
(4) 1/4-20 Stainless Nylon insert lock nuts
(3) #8-32x3/4" machine screws
(6) #8 washers
(3) #8-32 Nylon insert lock nuts

Conduct Tite
#85305 GM Weather Pack Cable Seal
#85303 Technician gauge connectors
#85315 GM Weather Pack Single Housing Male

Tools Needed:
7/16" Combo Wrench
9/16" Combo Wrench
5/8" Combo Wrench
11/16" Combo Wrench
7/8" Combo Wrench
15/16" Combo Wrench
1" Combo Wrench
11/32" Socket or Combo Wrench
7/16" Socket
12" Adjustable Wrench
Phillips Screwdriver
3/16" Allen Wrench
3/16" Drill Bit
1/4" Drill Bit
Dremel Tool



Laying out the system:
I first decided where I was going to mount the major components: Air Tank, Pressure Regulator, Oil Filter, Manifold and Relay. I figured that everything except the tank would go under the hood. The limitation under the hood is the distance of the Compressor Discharge hose to the Oil Filter. I do have the bracket for the Automatic Transmission Computer installed under the hood. This bracket originally was the mounting point for my Painless wiring harness that didn't quite withstand the heat under the hood, I found the resin melting out of it and some scorching on the connectors, so I removed the harness. My intentions are to install a marine grade harness into the Jeep later.

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Installing the Compressor Discharge Hose:
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Install the check valve on the installed compressor discharge fitting. This requires a 1" Combo Wrench, or a 12" adjustable wrench. You may need to Teflon tape the threads.
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Install the compressor discharge hose adaptor fitting to the check valve. You will need a 15/16" Combo Wrench for this and either a 1" Combo Wrench or 12" adjustable wrench to hold the check valve.
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Install the compressor discharge hose on to adaptor fitting. You will need a 7/8" Combo Wrench and a 15/16" Combo Wrench to hold the adaptor fitting.  The hose rides against the connection of the air filter box. This causes a little wear on the air box since it is only plastic. I do believe that if I had only a 1" body lift vice 1 1/4" I would not get any rub.
Route the Compressor Discharge Hose along the firewall to the driver side. This will give you a good determination as to the location of the oil filter. I had enough to allow for a loop back into the oil filter.  I used (2) 1/2" rubber insulated clamps to hold the hose and (2) 3/8" rubber insulated clamps to connect to the grill support rods. This provided good support of the hose and allowed for some flex in the hose during run of the compressor and movement of the engine. I will keep an eye on the clamp closest to the compressor to see if there is any wear from the heat and vibration.  I used a 1/4-20x3/4" bolt, (2) 1/4" washers and a nylon insert lock nut.  These require a 7/16" Combo wrench and socket. Dsc03365.jpg (550479 bytes)

Mounting the Oil Filter:

Since I had already determined that filter would not fit in the available space on the Auto Computer Bracket I still needed a place to mount the Oil Filter. I still didn't want to make a bracket for it and I was limited as to the distance that I could put it away because of the compressor discharge hose so I decided that hanging it off of the grill support rod right by the Cruise control module would be a good location. I did this by utilizing (2) 3/8" rubber insulated clamps around the grill support rod and bolting the bracket to them.  Once again this was bolted on using 1/4-20x3/4" bolt, (2) 1/4" washers and a nylon insert lock nut.  These require a 7/16" Combo wrench and socket. DSC03364.JPG (327276 bytes) 
Take a look at your oil filter.  There should be a direction arrow stamped into the body, or a marking indicating the inlet to the filter.  The Norgren filter has an arrow stamped into it.. You will install the compressor discharge hose fitting into the inlet side. DSC03070.JPG (335990 bytes)

Install the 90 degree compressor discharge hose outlet adaptor into the inlet side of the oil filter.  I had to rotate the bowl assembly around when I installed it in the Jeep.  I used the 12" Adjustable wrench to tighten this down.

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Install a straight air line fitting in the outlet side of the oil filter.  I originally installed one of the 90 degree fittings and later found that my routing didn't work quite right with it.  You will need an 11/16" Combo Wrench.
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Install oil return fitting to the bottom of the oil filter.  As you can see with it installed in the location, it fits perfectly into the hole.  Be careful, the connection on the bottom of the filter is plastic.  I used a 9/16" Combo Wrench.  You will also need to install the brass fitting and other connector into the side of the York Air Compressor. 
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The Oil Filter just rests in a bracket. I didn't like this since it seemed that it could easily jump out of the bracket or just move around in it. There were 2 small black screws that came with the filter, and didn't seem to fit in any of the holes except the two in front, so I screwed these in to hold the filter in place. The holes are not pre-tapped, so I only assumed that the screws went here.  Of course you use a phillips screwdriver to install these. DSC03363.JPG (347929 bytes)
Connect Compressor Discharge hose to oil filter inlet.  You will need a 7/8" Combo Wrench and a 15/16" Combo Wrench to hold the adaptor fitting.  
Mounting the Pressure Regulator:  

Install the pressure gauge on the regulator. I installed it with the regulator outlet to the right.  This required a 7/16" Combo Wrench.  I didn't get the gauge positioned perfectly, but it's more important that the gauge doesn't leak.

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Install plug on opposite side. You may need to Teflon tape the plug before installing it. This requires a 3/16" Allen wrench.
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Install (2) 3/8" 90-degree fittings onto Pressure Regulator.  I used a 9/16" Combo Wrench.
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Install regulator support bracket on regulator. I installed it with the L pointed down. The bracket only goes on with the mount holes in the front or the rear. DSC03074.JPG (352139 bytes)

I needed to mount it with the bracket up and over the lip of the Computer Bracket. This allowed the regulator to be located closer to the auto computer bracket. I marked and drilled the holes with a 3/16" drill bit.  I then used (2) #8-32x3/4" machine screws, (4) #8 washers and (2) #8-32 Nylon insert lock nuts to hold it in place. You will need a phillips screwdriver and an 11/32" Socket or Combo Wrench.

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Mounting the Manifold:
Install the fittings in the Manifold.  Some fittings may require Teflon tape to be applied before installation. With the limited space provided. I decided to install the (4) 3/8" 90-degree elbows that came with all the parts of the kit onto the manifold. The manifold has (6) 3/8" holes (1 in each end and 2 on each side) and (1) 1/4" Hole (in the top) drilled in it. The 1/4" hole is used for the pressure switch. I installed a 3/8" 90-degree elbow in each end and 1 in each side of the manifold (ended up being opposite side corners from each other). I installed the safety valve in the lower hole on what would be the inboard side and the connection for the air line to the in cab air pressure gauge in the other. I installed this fitting on the outside of the manifold so that I could later change it if I decided to go with a digital gauge vice the mechanical one.  Installing the fittings into the manifold will require an 11/16", 5/8", and 9/16" Combo Wrenchs.
This was my first set up that I had arranged.  Though after installing everything I realized that my arrangement didn't work in the area provided. DSC03083.JPG (343882 bytes) DSC03084.JPG (337640 bytes)
So this is the octopus that I finally ended with.  The air chucks are just installed temporarily in this picture until I route them to their permanent location.  The one that is pointed up actually rotates down so that I can close the hood. Dsc03372.jpg (442989 bytes)
The Off Road Only Manifold does not have any mounting holes in it, so I decided to use some 1 1/8" U-bolts to hold it on to the Auto Computer Bracket. I tried to get a good location where I could mount with all 4 ends of the U-bolts, but could only get 3 good ones. I mounted the Manifold vertically on the outer edge of the Auto Computer Bracket. I needed to trim down a couple of the edges to get the U-bolts to sit right.  I marked and drilled the holes with a 1/4" drill bit and tightened the nuts with a 7/16" Combo Wrench.  You will need to trim down the ends of the bolts.  I am still looking for some square U-bolts to fit this better. Dsc03374.jpg (485162 bytes)


Mounting the Tank:
Now the 1 gallon tank was for a test purpose so I needed to look for an area where I could later install a larger tank if I wanted to. This eliminated installation under the hood and since I didn't have a tire carrier or the desire to mount it in the back of the Jeep with the seat removed, I was pretty much limited to installing it under the rear floor pan just behind the transfer case on the driver side. This space has been used before for installation of compressors on other Jeeps with no ill effects. It is fairly well protected in this location.
Remove the plastic caps from the ends of the tank.  I needed a pliers to pull these out.
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Install fitting into the end of the tank.  One 90 degree fitting supports that large tube diameter, and the other 90 degree fitting supports the smaller tube diameter.  This fitting will go to the pressure regulator.  You will use an 11/16" Combo Wrench to install these.
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Hold the tank up into position and mark the location of the mount holes for the Tank brackets. DSC03095.JPG (337672 bytes)
Pull back the carpet from inside the Jeep to check for any obstructions and to prevent damage to the carpet. Dsc03097.jpg (426861 bytes) Dsc03098.jpg (573412 bytes)
Drill through the floor pan.  The drill bit size and bolts will depend on your tank size. Dsc03099.jpg (557088 bytes)

Install bolts and nuts to secure tank. This may require a second person unless your really ingenious or Mr. Fantastic with rubber arms.  I used some large fender washers to help spread the load over the floor pan.

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Mounting the Relay:

There was a convenient hole drilled on the front side of the Auto Computer Bracket. So I used another #8-32x3/4" Machine screw, (2) #8washers and a #8-32 nylon lock nut to hold it in place.  You will need a phillips screwdriver and an 11/32" Socket or Combo Wrench.

Note: The relay allows for power from the battery to power the electric clutch on the compressor.  Otherwise you would have to run this power through the switch and/or the pressure switch.

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Installing the In-Cab Air Gauge:
One of the nice things to know is if you have enough pressure in your system.  Now since I like have reading close at hand I decided to install a gauge in the cab so that I could see. Dsc03082.jpg (475758 bytes)
There is a convienent mounting location just in front of the 4wd shift lever.  It provides a good view of the gauge from the driver seat.  I used the backing plate for the gauge to mark my hole that I needed to cut.  Move the 4wd shift lever to 4lo. DSC03102.JPG (343410 bytes) DSC03103.JPG (331916 bytes)
I then connected the fitting to the back of the gauge. DSC03085.JPG (320389 bytes)
Inserted the screws into the back of the backing plate.  These screws will press against the backside of the plastic, so you need to cut the hole just large enough for the gauge to fit in snuggly.  The plate goes over the back of the gauge and turns to lock in. DSC03105.JPG (356550 bytes)
Insert gauge through the console, and lock the plate in from behind.  I was able to get to the screws with a stubby screwdriver. DSC03104.JPG (349166 bytes)
I pulled the firewall plug that sits behind the console and drilled a small hole in it so that I could later route the air line from the manifold to the gauge. DSC03106.JPG (348929 bytes)
Compressor Power:
The kilby's compressor came with a fitting on it to hook up electrical power for the clutch.  Now you could easily just cut this fitting off and connect straight into the wire, but I liked the idea of being able to disconnect the compressor if I needed to remove it.  So a quick trip to Pep-Boys netted me the other side of the connection.  I also wanted to be able to turn off the clutch just incase something happened, like the pressure switch failing.  So I also picked up a safety switch.  Normally these safety switch's are wired so that you have to flip the cover to turn on the switch, but I wanted to have it the opposite way, so all I did was file off the little tang on the switch plate so that I could rotate it around.  I already had a switch for the locker override, so I put the compressor switch right next to it.
The GM connector parts.  DSC03303.JPG (362926 bytes)
Insert the rubber plug onto the wire, then crimp the end on to the wire.  Insert this into the plastic housing and close the end cover. DSC03304.JPG (334966 bytes)
Connect the fittings together.  This wire will run over to your relay. Dsc03366.jpg (555295 bytes)
Now the simple thing of just taking apart your dash and installing the switch.  See Locker Override for details.  The switch is fed from switched power and feeds the pressure switch on the manifold. DSC03107.JPG (343082 bytes) DSC03108.JPG (320113 bytes)
Now that I had all the major parts installed, I could start routing my air lines.  Routing of the lines is fairly simple.  Compressor to oil filter, to manifold, to tank, to pressure regulator.  From the manifold you have 2 air chucks, 1 pressure gauge.

This page last updated: 16-Apr-2008

Content and Design © 2002-present WanderingTrail,  Ron Seegert
Common Sense and Safety should always be observed when working on your vehicle or doing modifications. Jackstands, wheel blocks, disconnecting the battery are a few of the basic safety precautions that should be used and may not be mentioned in the write ups on this site. You are responsible for your own installation, these write ups are a helpful guideline and should not be taken as an official installation instruction. My write up may be different from the kits currently out there, so alwasy double check the manufacturers installation instructions when installing anything. I try to keep the site up to date with changes that have occured as I discover them, but may not have the latest unless someone lets me know. If you feel that an install is above your capabilities after reading my write ups, I recommend getting together with a club and getting some help. Only a few times have I needed to employe some actual help from a shop to get something done. Usually welding or A/C work.
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