Troubleshooting compressor and system parts.

[tevake]

After some searching here I've yet to find the info I need to determine the problem in the air pressure system supporting the air bags in the rear of my 345 classic motorhome.
When turning on the ignition switch the compressor pump starts running but I get very little pressure indicated on the dash gauge. Plus very little pressure at the air hookup in the rear curbside storage compartment.
Strikes me that the compressor part of the pump is not working even tho the motor is running fine. But when checking the system I found that one of the pressure switches is warm/ hot to touch.
The switch in question is at the upper right corner of pic included.

My question, before I start throwing parts at it is,, is this switch supposed to be warm all of the time? Could a failed switch here be causing the compressor not to be pumping air pressure?

Since the line straight to the aux air hookup is also very low pressure, I'm assuming the compressor is not putting out the correct pressure. But do want to determine if this switch could be part of the problem.

Thanks for any help!

Cheers Richard

[Inland RV Center, In]

Originally Posted by tevake

After some searching here I've yet to find the info I need to determine the problem in the air pressure system supporting the air bags in the rear of my 345 classic motorhome.
When turning on the ignition switch the compressor pump starts running but I get very little pressure indicated on the dash gauge. Plus very little pressure at the air hookup in the rear curbside storage compartment.
Strikes me that the compressor part of the pump is not working even tho the motor is running fine. But when checking the system I found that one of the pressure switches is warm/ hot to touch.
The switch in question is at the upper right corner of pic included.

My question, before I start throwing parts at it is,, is this switch supposed to be warm all of the time? Could a failed switch here be causing the compressor not to be pumping air pressure?

Since the line straight to the aux air hookup is also very low pressure, I'm assuming the compressor is not putting out the correct pressure. But do want to determine if this switch could be part of the problem.

Thanks for any help!

Cheers Richard

Baically, a switch works or don't work.

When a switch carries a high current, they will get warm and sometimes hot to the touch. That is normal in any circuit.

I would put a pressure gauge on the output of the pump, at the pump and see what happens.

If the pump shuts off then that would say it's working OK, since the pressure switch is set to a high pressure, at least it was when new.

Also, if the pump keeps running, you could have a leak in the tubing.

Andy

[HowieE]

When turned on how long does the compressor rum?
If it only runs a short time and shuts off the high pressure limit switch may have failed and shutting the system down.
If it runs for ever and the switch you mentioned is hot I would look for a leak down stream. compressed air is hot.
Try closing off the line that goes to the reserve tank and see if the compressor will shout cycle against a closed system. If it does the controls and plumbing is good and the problem is beyond that point.

[tevake]

Thanks Andy and Howie for the tips.

After checking the output from the pump it looks like the issue is there.
I'll be calling the Gast folks today to see about ordering their rebuild kit for the pump.

After calling around central Az. To RV repair shops, all said they don't repair these pumps. Just recommend replacement.

With the motor running well, and in otherwise good condition, I'm thinking an overhaul of the pump should do the trick to get it pumping.

I will update later once the parts arrive.

Any experience here in doing this sort of rebuild?

Cheers Richard

[Isuzusweet]

Not exactly but I have taken apart other pumps and do have a tip that seems to cover all scenarios.

Take pictures of all angles and make sure you hash mark (scribe a mark for example from cylinder to cylinder head for realignment purposes) all pieces before stripping. Number all parts in order of disassembly and also orientation (ie, smallest part of tube is attached to head). Also make note of different size bolts as they come out.

Biggest tip I have once you loosen a part and just prior to complete disassembly, if you're not sure of what's coming out, is to finish disassembly through a small hole (big enough to get your hands through and work) in an enclosed cardboard box. I'm not the only one that has seen something fly out at a high rate of speed, ricochet off the ceiling, a couple of walls and taunt me for days if not weeks. If it can fly away, it will and you will cry.

Goodluck.
Cheers
Tony

If you have to replace the compressor.....go ARB.

[tevake]

I'm glad to report that Gast Co. Came thru with a rebuild kit for the compressor and the overhaul went well and the compressor is now working well.

Funny tho. There was little to be seen to be wrong with the compressor once disassembled. So I did a cleaning of the parts and installed the new parts and reassembled. And yowza. Works fine now.

Got to celebrate the successes!

Cheers Richard