I had a Jabsco
PAR MAX 3 water
pump in my fresh water
system. It lasted about 4.5 years of full-time liveaboard
use. I think it would have lasted several months longer if I had not taken it apart to see what the problem was, and probably years more if I had realized last year that it needed repair.
Recently, I had a leak in another part of the system, which caused me to notice some rusty-looking drips under the pump. I found that one of the membranes was leaking water into the pump housing. At the same time, I believe air was getting sucked in to the water system, causing the pump to sound a little different. In the course of working on it, I spilled a LOT of rusty water out of the pump.
I would never have figured out how it was supposed to come apart if I didn't have the manual. The electric motor
shaft connects to the pump mechanism with a set screw, but the shaft is buried inside an area that is not accesible until you remove the motor
. It turns out that there is a rubber plug
over a hole; you remove the plug
, then stick an allen wrench through to loosen the set screw, then remove the motor
. The two shafts were stuck together too effectively, even with the set screw removed completely, so I ended up disassembling the whole thing, including cutting up the failed membrane and taking apart the motor, to get it apart. Rust on the shaft may have contributed to this difficulty, though the motor shaft would be fine if sanded a little bit.
Having got that far, I saw that the brushes
in the motor had pretty deep grooves ground into them. I could have ordered some replacement parts
for the pump, polished the brushes
in the motor, and put it all back together. The result would be a working, though noisy, pump. I decided didn't want to do all that.
My wife called around and found a "replacement" at the local West Marine
, which turned out to be a "PAR MAX 3.0" pump. The "3.0" pump doesn't look anything like the "3" pump. Notably, the mounting bracket does not have the holes in the same place, and pump housing (where the water is) is noticeably larger. The "PAR MAX 3.0" pump is NOT a drop-in replacement for the "PAR MAX 3" pump. It would not even fit into the space our old pump was in.
I ended up buying
a "PAR MAX 4" pump, which IS a drop-in replacement for the 3, but with a higher flow rate. The WM price
was US$167 (instead of $109 for the "3.0" pump from WM; suprisingly, I found other "PAR MAX 3" pumps for sale
online for around $140 - $150).
The new pump is a lot quieter than the old one. From the condition of the old motor, I think it is loud because of wear, which is not surprising for how hard we used it.
Things I did wrong:
- The pump was occasionally coming on for a second now and then for about a year. I looked for leaks
in the water system, but didn't find anything. Next time I will use this as a clue that the pump membranes may need replacing. I think if I replaced the membranes a year ago, I probably would not have had much rust damage. It would have been easier to repair, and I would still have a working (though still noisy from wear) pump.
- When the store was asked "Do you have a Jabsco
PAR MAX 3?", I assumed that the answer "yes" meant that they had a pump just like the one I was holding that said "PAR MAX 3" on it. I actually fault Jabsco, not the clerk at WM, for the close similarity in the names of two unrelated products. I further deprecate the "3.0" name for trying to look computery.
Things I did right:
- I took a paper pattern to the store to see that the mounting brackets and hose connectors on the replacement pump would be in the same place. I'm glad I bought it locally, so I didn't end up buying
the "3.0" version of the pump and having to mail it back.
- As a hack, I temporarily used a West Marine
brand washdown pump that I scavanged from another application. It looks so much like the PAR MAX 3 that I believe it could have been manufactured by Jabsco for WM. It survived TWO DAYS service
as the house water pump. When it died, I could clearly smell burned wiring
inside the motor. It had been used before, but not that much. I did not take this one apart to see what happened to it, but I suspect the pressure switch failed, leaving the motor drawing power even when it was stalled.
I'm happy that the pump didn't give us any problem for over 4 years. We live aboard, and we are not stingy about water use, so this pump has seen a lot of use. A few years ago, it even ran the tank dry once when the shower head
on the swim platform failed while nobody was home; it was still running hours later. As I said, I expect it would have lasted longer if I realized there was a problem and repaired it sooner.