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Headhunter Mach 5 failure modes?
After three years (in our ownership) of problem free operation the water pump in our Liberty is acting up. A few days ago on our current trip a few times the pump would not come on to flush the toilet or use water otherwise, though the breaker switch at the panel was on. Cycling the breaker turned it on and worked fine thereafter for a while. We usually shut the breaker off when leaving the coach, so not sure what would have happened if was just left on.
Yesterday while working in the area of the water bay I heard the pump cycling on and off. Looked for open faucet or water leak, none found. Seemed like every 7 seconds it would come on for a few seconds and shut off. It also had spells where it would come on quit for half a second and come back on.
We just shut it off and flipped the breaker on when needed to flush, as we had campground water pressure for every thing else. Acts like maybe pressure is leaking back through a seal or check valve?
Today on the road it has been fine so far. Comes on fills the need, shuts off, does not cycle.
Could this be relate to being hooked up to campground water pressure, maybe a check valve related to that is leaking and the pressure is pushing water back through the hose into the cg water supply, lowering the coach system pressure and causing the pump to come on? Get back home tomorrow.
Anyone experienced similar symptoms? Is it headed toward complete failure? I found some rebuild kits for about $100 online.
http://www.downwindmarine.com/Headhunter-Mach5-Water-Pumps-p-90891176.html
Anyone gone that route?
Also have an interesting story about replacing the Amana refrigerator “on the road”, including removing the windshield with a popsicle stick and bottle of dishwashing soap in a parking lot in Phoenix, but that will have to wait until we get back into spacedock.
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13 Replies
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You probably have the Liberty Reverse Osmosis system and it continually uses very small amounts of water. If you’re in a garage and it’s quiet, you can hear the water dripping into the holding tank.
Other than that, check valve or a leaking fitting.
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sounds a bit like pressure switch failure or the mother board, take the top cover off the pump, 4 phillips head screws and check for water, should be dry, but HH has a problem in the seal between the pressure water and controls. I have had failures with the pumps same as you describe fresh out of the box. I was told to pull the top cover every few month and check for water in that area, that tells me they know they have a problem
also normally the pump should not be on if you are on shore water.
as a last resort, HH has an new exchange pump for less money than an outright purchase. (they call it customer good will, to cover up their somewhat bad design and engineering) there are other pumps available, i am just not familiar with them.
Glenn
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Check the air pressure in your accumulator tank. As I recall, it should be about 40 odd pounds. This keeps the pump from cycling constantly for minimal water uses.
When I installed a mach 5 in my coach I did not have a separate accumulator tank (the previous model headhunter had it built in) and the pump would cycle often, overheat, and shut down.
By the way, I need to leave my pump on also when on shore water in order to get better performance from the toilet.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
I thought I read that we shouldn’t use an an accumulator pump with the Headhunter Mach 5.
Are there two versions of the HH Mach 5? One that doesn’t use an accumulator pump (older) and one that does (newer)?
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Thanks for all the replies. Where is the accumulator tank cited above? Also, where is the check valve Truk cites? I presume the pump has an output check valve and or there must be a check valve between the pump output and the input line from campground water to the coach or else the higher pump pressure would push water back through the connection hose to the campground system. Also you would not be able to unhook the hose without shutting off the pump which you can do without closing any manual valves even when the pump is on.
I remember reading a post by Jon that he never did find the accumulator on his Liberty. I did find a plastic accumulator tank behind the refrigerator when I pulled that out for attempted repair, then exchange. I assumed it was the holding tank for the reverse osmosis system, but did not verify the plastic line to the refrig came from that tank, it ran behind it and I did not dig any further. When I disconnected the blue 1/4″ plastic line from the old frig about a gallon of water came out of it then flow stopped, I assumed it was from the pressurized holding tank behind the refig, but could be otherwise. The reverse osmosis valve cited below was off at the time.
In response to Truk’s advice about the Liberty reverse osmosis system, that system was always there, and always turned off at the “to refrigerator” tagged valve in the water bay since I had the bus. The plot thickens a little here, I did open the valve after putting in the new refrig. as we wanted to use the icemaker and cold water dispenser. Thinking what you cited might be what was going on, I closed the valve, the pump still cycled. If this valve shut off the flow to the reverse osmosis unit, it should have stopped the pump cycling, but it still cycled. If the valve shut off the flow after the reverse osmosis holding tank, I would think it would have no immediate effect, but when the holding tank (if there is one – every reverse osmosis system I have encountered had one as the real time flow from these will not meet normal intermittent flow demands) was full, the system should stop making purified water and the pump cycling should stop. Also if it was after the tank, water should not have come out of the icemaker/drinking water feed line to the back of the refrig when I disconnected it from the old refrig, but I got about a gallon.
The valve is open now, and the pump is not cycling except once when toilet is flushed or faucet/shower water is used.
Don’t know what happens if use some reverse osmosis water or the icemaker draws some water, have not monitored pump when either happens. From how reverse osmosis works, a short time draw of water results in a long period of slow water draw to replenish the filtered water holding tank.
Will dig a little further now that I am home, will check under the pump control panel for water and trace some reverse osmosis lines to see what goes and comes from where.
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I still do not know specifically where the accumulator tank is on my coach, but I do have one, and it is working.
Actually I have two, but the second one I added and it is dedicated to the Headhunter toilet so I can make the toilet work with a small Shurflo back up water pump.
If you want to know if you have an accumulator tank let your pump cycle off, turn off the switch and turn on a faucet. If you have a tank water will run for quite a while. Mine will run for a couple of minutes. I may also have an RO accumulator tank, but I don’t know where that is either and I am not pulling a refrigerator just to know.
The pump should have its own check valve, but there is also a small white plastic one in the CW line going to the HW tank.
1999 XLV X-6872, liberty #440 -
The mach 5 is the current version of the headhunter water pump and does not have an internal accumulator tank. My coach came with the previous version of the headhunter water pump (jetpaq??) which had an internal (built-in) accumulator tank. If you change to the mach 5 and your coach does not have an accumulator tank (as mine did not) you will have to add one for proper operation.
Accumulator tanks retain air pressure to function and have a fill valve (same as tire) which should be checked if you have issues.
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In case anyone is of the opinion a healthy accumulator tank set at the correct pressure is not needed consider this. First, it stops a pump from short cycling. That means you won’t have to hear the pump kick on immediately if there is any kind of water drawn, including the water used in the RO system.
But its biggest advantage is it protects your HW tank temperature pressure valve from being overworked. That valve is not intended to be opened and closed a lot of cycles. But if you do not have a functioning accumulator every time the HW tank heat from a relatively cool temp to its set point the expansion of the water has to go somewhere. If the accumulator has no air pressure the water expansion opens the temperature pressure valve, dumping water on the ground until the internal volume lost reduces the pressure.
But wait……….there’s more! If someone has replaced the pressure temperature valve on a HW tank like a Raritan with one they bought at Home Depot it might be the 175 PSI rating instead of the 70 PSI required and then the lack of an expansion tank, combined with the wrong relief valve makes the HW tank ends expand, and over time, instead of being flat, the ends get dome shaped. On some conversions then the HW tank is wedged between the bay floor and the underside of the coach bay ceiling, and if it has to be replaced it means the tank has to be cut into pieces with a Sawsall.
It is the little things we find out the hard way that really bite us in the butt.
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Jon:
Sounds like this expanding hot water tank issue came from a personal experience.
Chuck
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Did some checking on the Mach 5 today.
Bus parked in driveway not hooked up to outside water. Turned on pump, it ran a few seconds shut off, stayed off. Ran some water in sink for a couple seconds then shut off. Pump came on then shut off and stayed off.
Drew some reverse osmosis water from new refigerator, about half a glass. After a few seconds pump came on ran a few seconds then off. 7 seconds later came on ran a few seconds then off, reapeat, repeat. Went out and shut of “to refrigerator”ball valve in reverse osmosis water line. Pump stopped cycling. So the slow cycling was normal operation with reverse osmosis replenishment.
So I think my worries were self inflicted. When I started using the reverse osmosis system, the pump acted as it should, keeping pressure up to X level.
I did test for presence of a water pump accumulator, there is none. With the pump shut off you only get about 1 second of water flow that tapers to nothing quickly. It has always been this way with no ill effect. The pump ran when water was needed and then shut off.
As to why a couple times earlier in the trip before the refrigerator replacement and turning on the reverse osmosis, the pump would not come on when water was need or the toilet was flushed despite the main panel breaker being on I still don’t know. Also not sure why on my close observation while it was hooked up to campground water pressure it kept cycling on and off immediately (causing me to just shut it off and only turn it on to flush the toilet), I also still do not know, but suspect has something to do with the check valve that stops coach water pressure from pushing water back to the campground supply leaking.
I did not bother to pull the control panel/cover off the top of the pump to look for water as there was reason for the cycling behavior and I figured if it ain’t broke, don’t take a screwdriver to it.
When get some time will hook up water hose from house and see if I can duplicate the fast cycling.
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Chuck, No personal experience with tank expansion or use of the wrong temperature pressure valve. But on XL coaches with the Raritan HW tanks there have been several owners who had the problem who experienced the joy associated with having to cut a wedged HW tank into pieces to remove it from the bay.
I think that model coach has such limited bay height it doesn’t tolerate much tank expansion before the tank is wedged in place.
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You don’t have to believe me, but you need an accumulator tank if you want to reduce wear on the pump. In Arizona in the summer with fresh water tank temps about 100F, my first mach 5 without an accumulator tank would overheat and shut down.
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Here is a page with a video link Headhunter just sent me for an issue I am having on a boat. It pertains to any Headhunter pump installed in a coach or boat.
Chuck
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