On my way to Florida in October, I almost made it. About 50 miles from my RV park, along I75 near Sarasota, I began losing air pressure and my air brakes started dragging.

I pulled over and discovered my air dryer was venting pressure. When the air compressor hits full pressure (about 120 psi) the compressor kicks off and the air dryer is supposed to vent briefly to dump air from the dryer. Unfortunately it was stuck open and venting constantly. I was unable to get the dump valve to reseat and hold pressure.

I had a small compressor with me. I fired up the generator, plugged in the compressor and attached it to the air service fitting in the front of the coach. Even with my additional compressor I had barely enough pressure to keep the brakes off. I limped to the next exit and pulled into a nearby ball field parking lot.

I called a service guy, who showed up promptly. We decided we could just bypass the air dryer temporarily to get me to the park. He had the necessary fittings to connect input and output lines together and I drove the rest of the way to my site.

The air dryer is both a dryer and a filter so it is needed to prevent contamination of the entire air system. It is mounted on the outside of the right frame, near the engine. I removed the air dryer. It was dirty, corroded, and 25 years old. One input hose, one output hose, one small control hose, an electrical heater plug and a couple mounting bolts. New ones are no longer produced but there are rebuilt units available.

It pays to shop around. Rebuilt units went from about $400 up to almost $600. Some suppliers had them in stock, others were backordered. Some required a $120 core deposit, others not. I found one on Ebay for $419, free shipping, no core charge.

I had to remove and reuse the original input and output hose fittings and a small bypass line between them. Also I had to splice my old connector onto the new unit wires.

New and old units:

New one ready to go:

Using an exact replacement saved me having to change mounting brackets. It mounts vertically with a bolt at the bottom and a clamp ring around the middle.

Installed and ready to go. Looking forward alongside the frame. Stainless input line from compressor, output to the chassis.

I will pressure test next time I start.

Pressure tested ok. Good to go.

Knowing that it was ok and easy to bypass the dryer would have saved me time and money on the side of the road. As it was, I only lost a couple of hours and I was in a safe place.

When I get home, I plan to replace the stainless hose from compressor to dryer. It is kinked and it appears to be OEM. I will probably replace the governor on the compressor as well. Most of the other air system components have been serviced or replaced. That should take care of my air system for a while.

Have Barth, will travel again

I had a similar problem 2 years ago returning from Florida. Fortunately I was at a rest stop and discovered it when I started the engine and the pressure would not go up to more than about 60 lbs. I was lucky because I was able to stop the constant air leak from the valve and continued home. It has worked ever since but I thought I should change it to be sure. Unfortunately the bolts that attach it to the frame are sandwiched between the main frame and the engine pull out frame so I could not get to them to get them off. How did you do that Steve? Maybe yours was attached differently. I am not sure how I am going to be able to get them off.

Also, I have a farmer friend who has 3 semi tractor trailers for hauling corn and when I told him that all I could find to replace it were units that had 3 ports not two, he said what he does is just remove and plug the 3rd port which I guess is a feedback to the newer compressor systems. His trucks are all old and have the same 2 port air dryer as ours does so hopefully that will help.

Since I replaced mine with an identical unit I left the mounting bracket attached to the frame. There is one bolt that screws through a right angle bracket into the bottom of the dryer and a clamp ring around the middle of the unit.

Mine has a large braided hose going into it from the compressor (1/2 NPT), another large hose (1/2 NPT) out to the chassis and one small hose (1/4 NPT, I think) that is a feedback line from the compressor.

Look at the second picture. Input is on the left, output in the middle, and smaller feedback on the right. At 6 o'clock is the bottom mounting bolt.

In the last picture you can see the clamp ring around the center of the dryer.

Thanks Steve, that is a big help for me. I have been a little anxious about it since that problem happened to me. So far it has been flawless after the one episode. I will look into getting one of the rebuilt ones.
I tried everything my buddy and I (were both gearheads) to get the sandwiched bolts loose but could not figure a way to hold the heads between the two frames. Not a good design Spartan. Thanks again Steve. I am going to try to make it to the get together in MN in June so hope to see you then. We will be out of town for a few days, returning Sunday night before the get together. So if all goes well, I will fire up the Barth and come down there on Monday.

quote:

DA33100X

This is a follow up to my first post. I realized when I re read it that what I said about my farmer friend was off by 1 hose.

My system, and yours Steve, has 3 hoses, the supply line from the compressor, the output or delivery line to the tanks, and a third control line going back to the governor on the compressor which controls the purge.

What I came across when I was trying to get a new replacement was that the one recommended by Spartan and others, had a 4th line, which keeps a charge in the supply line. Our system isn't designed for that type so that is the one he was saying they just disconnect and plug both ends. That makes sense because then you have a standard 3-line system like ours.

Here is a good description of the difference. https://www.youtube.com/watch?v=EAZJuaX1xNM
Sorry for the confusion.

Thanks for the info! Could help other members too.