Introduction: On-Board Air Compressor / Welder for Vehicles

When we go to help on a project we usually only take out battery powered or hand tool. We have to leave our pneumatic tools at home, with a on-board air compressor we dont need to leave our pneumatic tools in the shop anymore.

Step 1: To Start Off - Why Do I Need a Air Compressor?

Why do you need a air compressor on your car or truck? There are a few answers.

You can:
1. pump up a tire
2. change a tire(with a impact wrench)
3. inflate you favorite water toy
4. paint a car (with a paint sprayer)
5. put on a roof(with a nail gun)
6. power a spud gun
7. Make: something
8. Because its cool

I could make this list go on for a while. Anything you use your shop air compressor for you can use this on-board air compressor for.

You will probably find a use for it you never thought you could use a air compressor for! I know I did. (supercharged a charcoal grill)

Step 2: Safety

Now before you start, you need to think this over, this instructable requires you to harness high pressure air, and do some modification to your vehical. If you dont have mechanical knowledge or just dont feel confidant in you abilty to do this safely, Please dont. There are kits avalible that you local mechanic can install for you.
Now if you do continue, please note I accept no liabilty for any results from information contained in this instructable and any information should be only taken for intelectual or entertainment value.

That being said, lets start building!

Step 3: Whats Involved

This instructable shows how I installed an air compressor in a Jeep Wrangler, not all vehicles are the same so this should only be a guide.

When we think of a air compressor we thing of that large tank, motor, and pump we have tucked into a corner of our shops. Its chugs along pumping up its air tank till we release that air as usable work with a pneumatic tool.

The compressor we are going to use in this instructable is one you would actually expect to see under the hood of a car, a Air Conditioning compressor.

Some would say 'those can only pump freon!' in that thought they would be incorrect, a AC compressor will just as happily pump air as it once did refrigerant.

This compressor will be driven much like it was originally by a belt, either V or serpentine depending on the type of compressor.

In the diagram below you can see just how the componets will work together to run your air tools.

First we have the compressor, taking in air and pushing it forward though the oil separator. After the separator is goes onward toward the manifold where in interacts with the pressure switch, popoff valve, before going to the air tank. As pressure build it will open the contacts on the pressure switch disconnecting compressors clutch stopping the air flow until the air pressure drops enough for the contacts in the switch to close again.

Next we will look as the tools we will need.

Step 4: The Tools, Equipment and Parts

Any one will tell you a good set of tools will take you far.
Now for the tools we will be using, some are required and some are use for ease of use.

The required tools:

A set of wrenches metric and standard
A ratchet wrench with metric and standard sockets
A hammer
Misc screw drivers,
Wire strippers and crimper
Teflon tape
Drill with a decent bit set
Bolts, nuts, and misc

The recommend but not needed tools:

MIG Welder
Angle Grinder
Plasma cutter
Drill press


For the On-Board Air:

A automotive AC compressor (Sanden, York 210, or RV2)
A oil air separator
Two pieces of 1/4" plate steel 10"x10"
Misc scraps of angle iron and 3/16" steel plate larger than 3"x6"
A 150psi pop-off safety valve(or other PSI depending on your pressure switch)
A 145PSI pressure switch with contact good for at least 10amps
A pressure gauge good for 0-200psi
Air hose 50 feet (for my jeep I used about 30 feet the excess gives you a short hose to keep in your vehicle)
Hose barbs to fit your hose
Misc pipe elbows, Tees, nipples, and bushings
A air tank ranging from 2.5 to 8 Gallons (I use a 6-7 Gallon tank)
And quick disconnect to fit your air tools

For the On-Board Welder:

A automotive alternator (CS144 or Ford 1G alternator)
Miller panel welder connectors
A Stinger(rod holder) rated for 300amps
A ground clamp
Two 20' foot sections of 4 gauge welding cable (you could use thicker and longer cables I chose 20' of 4 gauge for storage size reasons)
A SPST toggle switch ratted for 30amps
Non-avalanche replacement diode pack if your alternator comes with avalanche diodes

The cost:

Air compressor:

RV2..............$35 (autoyard)
Oil sep..........$19 (lowes)
Hose............$18 (harbor freight 50' had 28' extra)
disconnects....$5 each ($15) (ebay)
pres switch.....$14 (ebay)
pop off.........$7 (ebay)
belt.............$12 (napa)
Combo pulley..$60 (quadratech)
Gauge..........$5 (ebay)
switch..........$5 (ebay)
Manifold.......$10 (if you bought one from ebay I built mine out of pipe fittings)



CS-144.........$35 (autoyard)
1G diodes.....$17 (alternator shop)
cable...........$65 (40feet @ $1.62)(welding shop)
connects.......$15 each (jacks) (welding shop)
connects.......$12 each (plugs) (welding shop)
project box....$4 (radio shack)
Stinger.........$7 (welding shop)
grd clamp......$11 (welding shop)
switch..........$6 (radio shack)
belt.............$8 (napa)


Step 5: Which AC Compressor to Use?

Now there are three differnt AC compressors we can use.
A Sanden type compressor which is most likely already installed in your vehicle.
A York / Tecumseh 210 which were used in many from the 70's to mid 80's in many cars and trucks (volvos as a good source)
And the mopar RV2 which was used in many Chysler V6 and V8 cars and trucks from the 1960s to early 1980s

The sanden compressor requires the least amount of work, but does require you to remove your vehicles air conditioning. To use the sanden the AC system must be emptied of freon at a AC shop then a air line oiler is installed on the intake port and clutch wire is separated from the vehicles wiring harness. While this is the easiest route it is not the best as the sanden compressor will freeze up if not oiled correctly and does not pump as much air as a York or RV2.

The York compressor is a aluminum, twin cylinder air compressor with a oil sump which can come with V and serpentine belt clutches and comes in three models 207, 209 and 210. It can be mounted either upright or on its side depending on its location.
To identify the different models the clutch is unbolted then you look at the exposed crankshaft. A York with a shaft with a beveled edge is a 207, a shaft with a grove in it is a 209 and a shaft with a sharp edge is a 210. While any york will work the 210 model is preferable with its 10.2 cubic inch displacement. I've found the many Volvos carry the 210 model.

The RV2 is a heavy cast iron V twin compressor with oil sump and usually a dual V belt pulley. It requires more complex brackets than the York and has to be mounted upright and there is no serpentine belt clutch available. It also requires removal of a check valve from the intake. But is has a 12.5 cubic inch displacement and with its cast iron constructions I believe it can dissipate more heat and be run longer.

I am using the RV2 in this instructable as it is the first compressor I found, You can use which ever is easiest or available, because other than the mounting bracket all other instructions are the same.

Step 6: Removing the Air Filter/tube

In my vehicle a 2.5L Jeep Wrangler you have to remove the stock air filter and air tube. We will be replacing is with the air tube from the 4.0L wrangler to this tube we will attach a cone air filter.

To attach the cone air filter we must cut off the flexible ribbed section of the 4.0L air tube. With the cone air filter will come a set of rubber adapter rings the smallest of these rings will need to be pressed over the straight end of the air tube. Once in place the filter can be locked on by tightening the attached pipe clamp. The opposite end of the air tube will need to be pressed down over the throttle body and then tighten it with th attached pipe clamp.

To cover the cone filter a shop-vac filter bag should be put over it to catch any excess mud or dirt. It can be held on with a larger rubber band.

Step 7: Mounting the Compressor

When using the Sanden compressor it can stay in its current position.

But with the York and RV2 a bracket must be fabricated. Because of different vehicles and mounting locations this will be different for every body.

When using the York compressor in a Jeep wrangler with-out AC, the bracket can be very easily made. Simply a piece of steel plate with the appropriate holes drilled in it, four for mounting the plate and four for attaching the compressor. Through these holes the York will be bolt to the plate and the plate bolted to the engine. If you have AC in your jeep a bracket can be purchased from Killby products / Onboard Air.Com That will mount it parallel to your current AC compressor.

Now for mounting RV2. A RV2 compressor requires support from the front and side, to accomplish this a offset inverted 'T' shaped bracket with a extension on the front to support the compressor will be needed. Two section of 1/4" plate will be welded to together to form the 'T' segment, the bottom plate of the bracket will have four holes drilled in the corners to allow it to be bolted to the engine. The front bracket will need to made from the original RV2 front bracket or a section of plate no thicker than 3/16" inch.

Step 8: Setting Up the Plumbing

First we will install the output air lines on the York this requires the use of compression, flange, or Roto lock fittings most are available at your local auto parts store.

Attaching the air line for the RV2 requires some fabrication. Either the milling and then tapping of a block to fit a O-ring and pipe thread to the oil separator, or welding of a pipe to the original output flange, I chose the welding option.

Now that the output pipe is installed you must install the oil air separator. This is needed to help capture the excess oil that is in the air leaving the compressor. At the bottom of the separator is a small stopcock in most new units the stopcock is easily broken plastic. After mine broke I threaded the hole to 1/4" NPT and installed a 1/4" ball valve.

Connected to this valve is a hose which is your oil return. This hose in then connected to the oil filling port of your compressor. if both the RV2 and York 210 this port is already threaded for 1/8" NPT so a hose barb is easily installed.

As the oil builds up in the separator you open the valve while the system is under pressure. The compressed air will force the oil back into the compressors oil sump to repeat the process.

From the oil separator you go to the manifold attached to the manifold is one of the most important components the safety pop-off valve I used one set to 150psi do not go high as most air fitting are not rated for higher. Along with the pop off valve is the pressure switch in this case it turns on at 110psi and off at 145psi allowing the system to cycle on and off as needed.

Also attached to the manifold is a quick disconnect, the type you use will be dictated by the type of air fitting you use on your tools. I installed a industrial quick disconnect for my tools and a universal for the times my I use tools with automotive fittings.

The last connections on the manifold are the ports for your air pressure gauge and your output to your air tank, the last part of your air compressor.

Step 9: The Electrical

The electrical systems for the onboard air consist of the same connections no matter what type of compressor.
A wire to the compressors clutch,
The connection from the clutch to the pressure switch
The main on off switch(A covered switch is good for this)
And the fuse and connection to the vehicles electrical system

Step 10: The Air Tank

For any air compressor system you require a air tank for storing the first burst of air any air tool needs when it first starts. In a jeep wrangler there is a larger area under the body between the driver seat and rear axle where a tank can be mounted. In another vehicle there mounting location will probably be different.

The air tank I chose is a old Ansul Redline cartridge fire extinguisher the 30 pound model that I got from a local fire extinguisher shop for free. I measured its volume to be around 6.7gallons. To attach the tank to the jeep I used to 12" sections of 1" square tube that I welded to the side of the tank. The Ansul tank is think enough that you don't need to worry about its structural strength.

If your near a auto wrecker that specializes in tractor trailer or large trucks you can easily get a air tank with the appropriate fitting and ports for about $20.

Step 11: Why Do I Need a Welder?

If your going to be using pneumatic tools, sooner or later you will be building something that requires a welder.
1. Lets say your helping with a friend with a project that doesn't have that big of a work shop and has no welder and you don't want to run home of get yours.
2. Your needing to fix your lawn tractor that broke down far from a power outlet.
3. Welding is cool and a good skill to know

While these situations may not come up very often,
its better to have it and not use it, than need it and not have it.

Step 12: Safety

A stick welder uses high amperages and voltages (over 90 amps and around 90 volts) Because of this proper safety equipment is required.

A welding helmet (I prefer auto darkening)
A pair of leather welding gloves
A welding jacket or apron

Now some more safety tips,
Keep both hands on the stinger(rod holder) at all times while welding, this will keep you from touching the grounding work piece and creating a connection through yourself.

And also never weld Galvanized steel, unless your wearing a respirator with the correct filters.

Step 13: Which Alternator to Use?

When building a on-board welder you first have to select the right alternator.

Possibilities are:
ford external voltage regulator alternators (the 1G large case alternator is good)
GM-Delco CS144(this is the alternator I'm using)

The ford 1G large case can be used directly as it is, just connect the power line from your switch to the field connector and your cables to the terminals. But as I just said the Large Case alternator is Large, it also usually has a out put of around 90 amps which means it will require higher engine RPM to weld with it.

The CS-144 is a 140amp alternator with 32volt avalanche diodes to use this alternator in welding you must replace the rectifier diodes with a Transpo: FR-1270 or FR-1290 diode pack. To weld it also requires you to remove the voltage regulator and solder some internal components. The bright side of the CS-144 is it requires because of its high amp output a lower engine RPM to weld with it it is also smaller than the Ford alternator.

Step 14: Modifing the Alternator

When using a alternator without avalanche diodes you can just remove or bypass any voltage regulator and attach your power wire directly to the rotor power brush.
If your alternator has avalanche diodes like the CS-144 I'm using you must remove the diode pack and install a non-avalanche diode set.

In the CS-144 you must remove the voltage regulator and cut its connection to the brush holder, this is where we will solder out power lead. After its attached feed it out the back of the alternator case.
Now we must remove the diode pack, the diode pack is attached to a plastic frame carefully pry the diode heat sinks off it. We will be using it to hold the stator leads.

Once the diodes are removed we will crimp or solder to the stator leads three pieces of 10 gauge wire, these wire will to be fed our the back of the case where we will solder them to a diode pack from a ford 1G. If you cant solder the wires from the stator use a Transpo FR1290 diode pack your local alternator shop can order you one, this is a more heavy duty diode pack which uses screw terminals.

Now that the diode pack is attached we must re-seat the brushes:

1. First unfold a paper clip.
2. Now on the rear of the case near the bearing cup is a small hole.
3. Reach into the alternator case and push the bottom spring and brush back into its holder.
As you get the brush back in place push the paper clip into the small hole it will feed up in front of the brush holding it in place
4. Repeat this with the top brush.

You can now reinstall the rotor and upper case once its all bolted back together you can remove the paper clip.

Step 15: The Cables

The connections from the diode pack should be insulated from the body of the vehicle. From the diode pack we go to which ever type of terminal you will use for your cables. I chose Miller panel connects you can order these online or from your local welding supplier.
The Welding cables you use should be at least 4 gauge wire, to handle the voltage and amperage going through them, My cables are 20 feet long if you go longer consider going to a larger cable to keep the cables from over heating.

Your stinger or rodholder should be rated for atleast 200amps. The ground clamp should have good spring tension for ensure a good ground. You can pick up either of these at you local welding shop, Sears, or Harbor Freight

One of the things people try to skimp on is your welding helmet or hood, Buy a descent brand name one if your first learning to weld go for a auto darkening it will make things easier.

Step 16: Mounting It and Wiring It Up

Once its all wired up we must attach the belt and tension it. For the CS-144 I made a tensioner from a section os 8mm all thread bolt and a jeep serpentine belt tensioner block.

On the section of all thread I butted to 8mm hex nuts together tightly to form a block. This block is put through a hold in a piece of 3/16 plate that I attached to the top of the RV2 On the other end of the all thread is screwed into the tensioner block as the nut-block is rotated the alternator is pushed back tensioning the V belt.

Step 17: Now Thats Its All Done Lets Test It Out!

Now we have done it the On-Board Air Compressor and Welder are completed lets test it out!

This is the first part of the video

This is the second part of the video

A couple of things to keep in mind remember to check the oil in the oil separator ever few uses to keep it from over filling and the compressor from run low on oil. And remember to keep your belts tight, and wipe off any oil that may get on them.

Now that you have your onboard air/welder system see if you can go out and use it to build something!

I know I am! (got talked into helping put a new door on a barn on tomorrow)
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