I mounted an A/C compressor in the engine bay and after a couple years of use I can honestly tell you that it’s the best modification I ever did. I highly recommend that any serious traveler should install one.
The compressor performance is awesome. It inflates tires jut as fast as a regular full size shop compressor. Since I have 2 outlets, we often use the compressor 2 at a time with no problem. I air up my 31x10.5x15 from 10 PSI to 30 PSI in 20 to 30 seconds. When traveling in more than one car over long stretches of sand and getting stuck often, electric compressors will slow you down severely. Now, my friends don’t bother getting their electric compressors out and just use mine and we still start moving again much faster.
Most important of all, with this pump I can reseat the tire on the rim after repair. That’s something no electric compressor can do.
The whole thing ended up costing me less than a good quality electric compressor but installing it is a bit more involved.
Following is a description of what I did. All these parts, even if they sound alien to you are standard air compressor parts and can be found almost anywhere. Let me know if you need any help with this. It’s very easy once you understand how it works.
Here’s what I did:
The Compressor:
I got hold of an old York compressor. These were used in a number of Mercedes and Volvo cars over the years. There are 3 sizes; I got the biggest one that has a displacement of 10 cubic inches. (If interested I can tell you how to differentiate them). The thing about the York is that it’s a vertical unit with the crankshaft (and oil) at the bottom, so the air doesn’t mix that much with the oil. So very little oil comes out of it, which means less work for the oil filter and longer periods between compressor maintenance.
A metal fabricator made me a mount to mount the compressor right next to the air conditioning compressor in my Jeep. I got a replacement alternator pulley that had an extra groove and connected that to the air compressor with a small belt.
You HAVE to oil the compressor since it’s basically a crankshaft, connecting rod and piston. Would you run your engine without oil?
Input / Output:
I installed a small air filter to the compressor input and an oil filter to the output. Since the York hold the oil at the bottom I only have to top off the oil every year or so. But it has to be oiled.
Plumbing:
The air coming out of the compressor goes through:
One-way valve with pressure relief: This holds the pressure in the tank while relieving the pressure in the airline linking it back to the compressor. This lightens the load on the compressor when it starts pumping again.
Pressure switch: This is connected to the compressor wiring. It turns it on when the pressure drops below 80 PSI and off when it reaches 130 PSI. It is linked to the one-way valve with a thin tube to relieve the pressure when the pump stops.
The Tank: an old fire extinguisher bottle with a pressure gauge attached to it.
Relief valve: Also attached to the tank. When it gets hot the air in the tank expands, thus increasing pressure, the relief valve lets the excess air out and maintain the tank pressure at 150 PSI max.
From the tank I plumbed airlines to the front bumper, the rear bumper and inside the cab. All air outlets are fitted with quick disconnects couplings for fast operation.
Uses:
Naturally I use it to inflate the tires. But I also use the in-cab air outlet to clean my camera equipment as often as I can while driving.
The compressor it powerful rnough to power air tools. I carry a ½ inch gun that comes in handy in a variety of situation, like changing a tire.
Since this thing outputs monstrous amount of air very quickly, I now carry a full size 25 cm thick air mattress to sleep on. It takes me only a few minutes to inflate it and now I always wake up fresh
. I also adapted a blender “top” (the thing you put the fruits in, whatever that’s called in English) to run off the air gun
. Fresh juice, milk shake or margarita anybody??
As I said above, this is the best modification I ever did and I’m very happy with it. Every serious traveler should have one installed. Let me know if you need any help figuring and installing a similar system and I can get you pictures of my setup if interested.
Take care,
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A.B.
www.ShortWheelbase.com
[This message has been edited by A.B. (edited 21 April 2002).]