Air Compressors

For the first couple of years, I used a 1 hp compressor then a 2 hp compressor which I nurse maided along until it died. Then I broke down and bought a new 5 hp compressor with a 60 gallon tank. This page is about making do with el cheapo used compressors to get the most out of them...

As soon as I started to seriously work on the body, it became very obvious that a 1 hp compressor just won't cut it. I picked up a 150 psi, 2 hp compressor for dirt cheap ($100). It was about 30 years old but as I found out, the tank was shot. The bottom was rusted out and there were holes plugged with screws. It was so rotten I could push a screwdriver through the metal. Even still, the compressor would pump up to 150 psi which is quite a feat!

I picked up another propane tank (30 gallon) from the autowreckers for $12 and converted it into a compressor tank. The metal is at least 1/4" thick on the propane tanks!. Now I have around 70 gallons of air reservoir and lots of pressure for the air tools - nice! I actually did some pretty nice welding putting it all together!


New renovated 2 hp compressor

There was a pickup truck at the wreckers that had what looked like a 100 gallon propane tank in the bed and man was it tempting. I was thinking that I could stand it upright and put the compressor on the top but it was just too big for my garage. It would of cost only $12 too.

I had to clean pretty much everything on the compressor including taking apart the pressure regulator. The pressure regulator usually fails for two reasons: dirty or the rubber diaphragm breaks. In 90% of the cases, the regulator just needs to be taken apart and given a good cleaning which was all mine needed.

The pressure switch has a screw adjustment to set the on/off pressure for the motor. I set the off pressure to 125 psi and the on pressure is set to 100 psi. This seems to work quite well.

A good cleaning and everything tightened up and the compressor works like a charm. I attached a water/oil filter onto it that I currently have on my sand blaster. Unfortunately, this was after the oil rings went and was a little too late as some of the body primer is contaminated with oil and will need to be stripped and cleaned again.

Rebuilding the compressor

I used the "new" 2 hp compressor for about 4 months steady while stripping the paint off the car. This was a little too much for the 30 year old unit and the oil rings wore out. I had about a 2 foot square patch left to strip on the whole car and oil started to spew out the air lines. I'll have to strip and clean part of the front fenders now. Anyways, I had a choice to rebuild the compressor ($35), replace the compressor portion ($400) or buy a another used compressor ($500 for a 5 hp).

Well, money talks and I had never rebuilt a compressor before so for $35, I purchased a new set of rings. I figured it can't be much different than rebuilding an engine. In fact, it is easier. I took the compressor apart and cleaned the reed valves. The cylinder housing/sleeve is removed in one piece and the pistons stay attached to the crank. I replaced the rings with one small note to make. The dual oil rings have a spacer. It is important that the spacer be installed properly and not overlap at the gap ends.

I gave the cylinders a quick hone, made up a new gasket for the one that broke, coated the others with Permatex gasket adhesive, put everything together and it worked. I tightened the bolts to what felt like a reasonable torque setting in an alternating pattern using a 3/8" ratchet so that I don't overtighten them. Ran it until it reached full pressure, let it cool and retightened. It works great, it's quieter and no oil in the air.

It's interesting putting the compressor back together as the cylinder housing is slipped over the pistons. There is a chamfer on the bottom of the cylinders that aids in compressing the rings so you don't need a piston ring compressor. The trick is to lock the crank in place. I put two 2x2 pieces of wood through the pulley and locked them together using a bungee cord to jam the pulley from turning - it worked quite well.

Cheap air reservoir

I had a 1 hp compressor and 20 gallon air tank. I found that I was running out of air all the time. I picked up a 40 gallon propane tank at the local wreckers out of an old taxi. It's rated for 300 psi and should handle the 90 psi that I use with ease. The cost was $12.

The first problem that I ran into was the residual propane in the tank. I removed all the fittings and ran my shopvac on blow into it for about 30 minutes. I then left it standing for about a month to let it air out. That got rid of the majority of the propane smell.

I found that almost all of the fittings are standard npt fittings and I could get adapters and plugs to fit the tank's openings. I installed a 100 psi pressure release valve, a water release valve on the bottom, an air gauge, a shutoff valve and a male quick disconnect so that I can attach a standard hose from my compressor. I welded an old 15" rim on the bottom of the tank which made a very stable base.

Air reservoir

Propane tank standing upright welded to 15" rim

On the compressor, I added a female quick disconnect fitting on the unregulated side so that I could connect the new reservoir up to it and quickly remove it if needed.

Well, it works like a charm, it sits in the corner and doesn't take up much room since its in the upright position. I've got an extra 40 gallons of air and now my air tools don't run out of air as quickly. They are much more useable. Takes a bit longer to pump up the complete reservoir system but it sure is an improvement. I was talking to a friend of mine and he used one of the huge old propane tanks (look like a bbq tank on steriods) and it is about 100 gallon. It looks like it would be a cleaner setup.

New 5 hp Compressor

As I reached the stage where I was going to prime and paint the car, I realized that the 2 hp compressor just wouldn't cut the mustard. So I purchased an Eagle brand 5 hp upright 40 gallon compressor. Wow! is it nice. Only had to replace the electrical motor TWO times on warranty in the first month! It seems that they had a batch of bad startup capacitors with their new motors. There was absolutely no problem in repairing it and they even sent a service guy the second time. I chose Eagle because they are made right here where I live.

New hot rod compressor air filters

Of course, I can't leave anything alone so I replaced the pitifully small stock air filters with some old tripower carb filters for that hot rod look. The original filter consisted of a large sponge style filter and an absolutely pitiful housing that consisted of 3 or 4 razor blade slices for breathing! It was like sucking air through a straw, so a few trips to the hardware store, picked up a short gas pipe that threaded into the compressor. Found a round gas fitting that is used to make handrails and pop riveted it to the back of the new air filter.

Now the air compressor pumps up a little bit more faster. It's just an air pump and anything that you can do to improve the air flow makes it more effiecint. I wish that I had timed how long it took to pump before and after, then I could have a some solid numbers for comparison. How come you always think of this after you've made the changes? Oh well, it looks good and works better.

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Copyright February 2012 Eugene Blanchard