As the Trooper sees more and more time offroad and after a near stuck on the beach, I decided it was time to have the ability to airdown for offroad driving and air-back-up for on road driving. I looked at the viair medium duty system (rated for 31" tires) and decided for $288 I would DIY an OBA system instead of buying one.
One of the factors in this decision was output/duty cycle. Electric pumps are slow and can't run continuously. So I decided with a DIY system I could use a pump driven by the motor like a York.
Mounting up York compressors for OBA systems is pretty common, but in searching here on the planet I could not find anyone who did it and had photos, etc. So here is a quick account of my go at it.
PHASE I - getting the pump mounted aka "the easy part"
When I first got my trooper, I pulled the AIR system, so I had room and some brackets for an OBA system. Last week I picked up a pump from a motor home with a BB Chrysler at the local recyclers. Grounding the body and applying 12v to the clutch wire showed that the clutch was good. Spinning the part of the clutch attached to the crankshaft indicated that the pump was pumping ok too.
The York can be mounted vertically or horizontally, but in the trooper it fits best vertically. The bottom, left and right sides of the york hav 4 x 5/8" threaded holes that are for mounting the pump. Of course, some type of adapter bracket is needed to get one in the trooper. I decided to make one that would make use of the pivot bracket that I already had from the old air pump.
The emissions pump tensioner arm can also be reused. To do this a mounting point needs to be fabbed for the York and somewhere on the motor. I chose the two threaded holes at the front of the cylinder head.
All in all I need to make three brackets / adapters / mounting points:
1. Compressor bottom - from the bottom of the YOrk to the pivot from the old air pump (top left)
2. Compressor side - from the side of the york to the tensioner arm from the old air pump (bottom left)
3. Cylinder head - from the cylinder head to the other side of the tensioner arm. (bottom right)
You can see these three brackets, the tensioner arm (top right) and the pivot (bottom center) here. The brackets are all made from 3/16 angle. The only tools needed were a drill, sawzall, angle grinder and a 110V flux core welder.
Here you can see the compressor bottom and side brackets attached to the compressor. The hole in the bottom of the lower bracket is for the long bolt that goes through the pivot bracket. It is tough to see, but there is a .125 wall tube on the bracket that the bolt goes through. The other two holes are speed holes aka "measure once; cut twice..."
A 1/2" x 28" belt from Napa got the pump hooked up to the the extra pulley on the fan. A 29 inch belt may be better, because the pump does sit slightly clocked (5 degrees or so). However, the hood still closes with plenty of spare room. The hose on the right is the intake. The fitting on the left is the high pressure side. I cycled the motor up to 4500 rpms a couple of times and the everything is rock solid. Clearance to the exhaust manifold is as large as I could make it without the compressor hitting the hose coming off the MAF.PHASE II - plumbing & wiring
I am waiting on parts for this. Should be done in about two weeks. Rough outline of the plan:
All on one manifold under the hood:
175 psi safety valve
110/ 150 psi high / low pressure switch with relay
Right after the manifold will be an inline oil / moisture / particle filter. Copper tube will lead to a 2.5 gallon tank under step in the rear floor. For now the plan is to have a single quick connect either under the truck or poking through the step behind the front drivers seat.
Main power will be controlled by an in-cab toggle switch to the low power (obviously) side of the relay.
Phase I was pretty easy. Phase II will be a little more work, but nothing terribly difficult. So far with compressor, plumbing, wiring, flare tool, tank and 1/4 npt tap I am barely under budget. By time I get the copper tubing, a handful of fittings and the toggle switch that I still need, I will probably be right at the cost of the viair system.
I got the switch and solenoid wired up. The power for both comes from the number 7 position on the fuse panel. You can tap into that, if you dont have power locks, right above the hood release handle. The six pole connector with 4 light green, 1 pink and 1 black wire is for the power locks. I used the simplest cheapest toggle I could find at radioshack. Unfortunately, even the simplest switch these days is fancy, I just wanted a plain old toggle switch.
Above: Toggle switch for compressor relay. Man is my trooper dusty.
Above: The switch I really wanted. I had this one in my tool box. I found the same type on the interweb, but they were like 6 bucks plus 5 more for shipping! Really?!? Btw, this one is the relocated clutch safety switch.
The relay also contained the pressure switch. So I needed a little room to mount it. Behind the drives headlight worked well.
Above: Relay-Pressure switch combo.
Here is the highpressure hydro hose from the compressor to the manifold. From left to right the items on the manifold are: 150 psi blow off, pressure gauge, quick connect, line to the pressure switch. Eventually the quick connect will be replaced by the blow off and in place of the blow off will be the line to the tank. Between the manifold and the tank there will also be a filter and check valve. I will have an extra blow off on the tank too.
Above: compressor to manifold.
I was able to run the copper tube from the manifold to the pressure switch with only one minor hang-up. The arm on the hood hinge nests exactly where I had the line running. Luckily the tubing is so soft that things just self clearanced. After the self-clearance bent the tube further out of the way so the hinge wouldn't rub through the copper line. I just happened to have some loom-holders from Del-city in the garage that worked perfect for mounting the copper line. I was able to run the line thorough the holders and attach the holder to the bolts holding the inner and outer fenders together. I thought that was pretty a pretty lucky fit.
You can also see the filter (muffler) from the AIR setup that I repurposed as a filter. You can actually crack the housings open and change the "element."
Above: overview of the setup.
It seems to work well although without a tank the flow rate is pretty small. If I prop the throttle open, I can, however, run a 1/2" impact wrench enough to get my lug nuts off... I was also very impressed that the motor could idle right up to 120 psi and hold it without getting bogged down.Phase III - tank & final plumbing
This has been done for a while now. There were some mods made to the manifold under the hood to make things fit better. The copper tuning was way too much of a pain in the --- -someone here warned me about that and I wish I had listened.
So, I used 300 psi from a hose I had in the garage with a damaged end.
[under hood pic coming soon]
Mounted the tank right under the rear step.
[tank pic coming soon]
Quick connect for airing up tires is just inside the rear driver's door. I am not too worried about folks stepping on this, since I only have front seats...