[360]

I'm kind of stumped.  So I had blown what I believe is a head gasket on a third compressor.  I tried to blame the other ones on overheating due to a failing of another component or the like, but this time I'm really scratching my head.

So last Thursday afternoon I replaced yet another compressor and I also replaced the a check valve that is just above that little module that releases the pressure back against the head.  Replaced that check valve as I had a little bit of air seeping back towards the compressor.  I absolutely have the check valve facing the right direction of basically air being input into the coach.  So I take the coach home, got all loaded up and washed up and noticed it came on a couple times over the course of 6 hours or so which seemed about right based upon how much it had been leaking down in recent history.  Went out in the morning and felt compressor and it was just barely warm as if it had run maybe an hour or so prior so I figured things were heading in the right direction.  Drove 5 hours to my destination and was there a couple hours and was back at the coach and heard compressor come on.  Again thought that seemed about right expept after about 10 minutes it was still running.  I go out and it's obviously super hot at that point and I also noticed yet again I had massive amounts of air escaping in between the head and the compressor in the port just to the right on the exhaust.  Same thing happened on the last two compressors.  

Any suggestions on what could cause something like this to intermittently happen would be greatly appreciated.  Compressor had maybe an hour of run time on it.

[HoosierDaddy]

Brad, Have u checked the compressor pressure switch? My coach is older so maybe different. I have a seperate switch ( it looks like a well pump switch) that controls compressor. The problem u have could be caused when the contacts in that switch stick closed or if the switch is not adjusted properly.

[360]

Brad, Have u checked the compressor pressure switch? My coach is older so maybe different. I have a seperate switch ( it looks like a well pump switch) that controls compressor. The problem u have could be caused when the contacts in that switch stick closed or if the switch is not adjusted properly.

I believe I do.  I’ll grab a picture of that bay in the morning.

[Richard]

You may have TWO grey boxes that power the compressor. The one that Dean described is the infamous well pump switch. As he stated it controls the cut in and cut out power. It usually will have Square D on the cover. You may have a second grey box, this one is activated by the HWH leveling system. If the leveling system is in AUTO, it will activate the pump, and most importantly OVER RIDE the well pump pressure switch. The HWH system is placed in AUTO by pushing the level (air) button twice.

If you pull the covers off either switch, keep in mind you will expose 120V live circuitry.

[360]

You may have TWO grey boxes that power the compressor. The one that Dean described is the infamous well pump switch. As he stated it controls the cut in and cut out power. It usually will have Square D on the cover. You may have a second grey box, this one is activated by the HWH leveling system. If the leveling system is in AUTO, it will activate the pump, and most importantly OVER RIDE the well pump pressure switch. The HWH system is placed in AUTO by pushing the level (air) button twice.

If you pull the covers off either switch, keep in mind you will expose 120V live circuitry.

Yes, for sure have two boxes.  The Square D and what I’ve previously called “the box my compressor is wired into”.  

In this latest pump failure the coach was shut down in what I call manual mode where I have pressed air button and raised and lowered coach to get level manually and then shut coach down.  

The night before coach was shut down on Off/Travel and it didn’t have an issue although it’s possible I may have blown a gasket when in travel in the past, but I can’t guarantee it.  

Last two have occurred when in manual leveling mode.  Hopefully some of this info helps.

Edit: After I posted this I re-read your response. I’m not saying it’s impossible that I hit the Air button more than once while I was manually leveling. Kind of like when I wanted make sure I was not in travel before I adjusted again. I don’t think I did that, but I would not bet my life on it.

[bikestuff]

As far as I remember about 653. The compressor did NOT come on in auto level mode. I am not saying it wasn’t supposed to…but as far as I remember it did not.

I cant imagine doing anything to one of these pumps that will cause it to break like this.

It’s a real mystery to me.

Bill

[Richard]

There is a very easy way to test to see if the HWH makes the compressor come on. Put the HWH into air mode. Press any of the up buttons. If the compressor comes on, then it’s something to be aware of.

I don’t know if this is related to your issue or not. But what I have observed to happen if the HWH is left in auto mode is the compressor will come on and run until something breaks trying to level the coach. In my case it was an air bag. On my coach there was a overpressure relief valve that was supposed to let off at 125, but it did not. Perhaps mine had been adjusted by a PO in the past.

Given that any of our coaches may have had modifications different from the factory, you will just have to make both a pneumatic and electrical diagram of YOUR setup to help noodle out the problem.

This is what I hear you saying, but I am using different words than you do. I install a new compressor, it works for a period of time, then it blows the head gasket, then it runs forever trying to build pressure.

Hmmm, what if it runs forever happens first, therefore causing the head gasket to fail. Chicken or egg deal.

[Richard]

Other things come to mind, so just asking about possibilities.

Did you install the plug in the other outlet port, or did it come from the factory with the plug installed? Is is possible the head cracked right there? Overtightening a NPT thread into that alloy head in an area that is thin could crack it.

[360]

Thomas compressor came with intake and exhaust marked and all other ports plugged.

Currently installing pressure gauge in 3/8 line to wet tank to see how much pressure we’re building before it cuts off. Does anybody know what proper cut in and cut out pressures are? Tried to do a search, but could not find.

[RussWhite]

I no longer have a Newell, but I may still be able to comment on this situation. If I'm off base, I trust I will be corrected. But it's good to understand how the system was intended to operate, at least with my vintage coach ( 1999 ).

As has already been mentioned there are two 120 VAC relays capable of starting and stopping the auxiliary compressor. One is the "well" switch with its adjustable start and stop setpoints internal to the switch, and the other is just a relay activated by the HWH leveling system. There should be a third component in this system which is a pressure relief valve ( regulator ) that should be set at the maximum allowable system pressure. In theory, the system should function something similar to this: Compressor comes on at the cut-in setpoint. I don't think this a critical value, but for me I set that at 75 psig. The compressor should run on the "well" switch until it reaches cout-out pressure. I set that to about 105 psig. Now things get more interesting....
If you choose to let HWH level your coach, which I often did, it will start the compressor so as to have sufficient pressure to raise the coach as necessary. When the coach is level, it stops the compressor. At that point I ALWAYS pushed the OFF button so the coach was no longer in auto level. Should you choose not to do that, HWH will try to level should your coach become out of level. You may be gone or asleep when this happens. HWH will start the compressor and open the appropriate valve/s to level the coach. What may happen is the coach will not level, but the HWH keeps trying as your compressor keeps running and running. Should the pressure relief not work or be set incorrectly, the pressure may rise to the maximum your compressor is capable of delivering. If you are lucky, the head gasket blows, if you are not, an air bag blows. That is way I disable the HWH from running my compressor and never left in Auto Level.

Russ