Arimitsu 516 chatter

[Waxman]

pump chatters when run normally. connecting a hose and spray gun assy to regulator ( eliminating downstream problem) did not change chatter. connecting garden hose to inlet smooths it out. Reconnect inlet plumbing. works ok for a bit then chatters again. cleaned valves numerous times. took head off. no cracks or holes in seals. pistons look ok. looked at arimitsu video but seals seem to be different than mine. mine has 2 seals that fit together after i remove retainer then there are 2 brass washer type things; one thin and one thicker. there is another seal in a groove inside seal retainer and that looks ok too.

i thought it was a water feed issue but that seems to be fine after removing all inlet plumbing, cleaning it all out thoroughly and verified flow from gravity tank to pump. tried a different regulator; no change. weird thing is it will work ok for awhile ( a week sometimes) then chatter again but cold water garden hose feed always smooths it out totally.

the pump does see some hot water for a day at a time when i turn the temp up to 140f to decontaminate boats for the DCR. could this have damaged seals in a way that i can't see?

I'm stumped. Any ideas? Try a new seal kit? I'm about to load the parts cannon!!

 

[Waxman]

it looks like my high pressure seal is two pieces. in the arimitsu video, the high-pressure seal looks like one piece. this is confusing me somewhat. However Gregg does say on the video that some five series pumps came with a back up ring with the high-pressure seal. Maybe that's what I have?

 

[Keno]

Wonder if you have a very small air leak and/or restriction in your intake plumbing that shows itself as a problem after some use time? My thoughts just based on pressure water from a garden hose curing the issue.

 

[Waxman]

I guess it's possible. I have removed all the inlet plumbing and thoroughly cleaned it all and reconnected using pipe thread compound and Teflon tape. There is a nylon braided plastic hose going from the water tank to the ball valve and I replaced that plastic hose as well. I guess I could try connecting the inlet plumbing from my other pump right next to this one to see if that changes things. One idea I got from a friend was that perhaps the pressurized water from the garden hose is somehow masking a compromised seal in the head of the pump…

 

[Keno]

I should have probably mentioned, I have 0 experience with arimitsu pumps, just going off cat pump experience.

 

[Waxman]

well… This morning I reassembled the seals with O-ring grease, put the head of the pump back on, dropped a three-quarter inch rubber hose into the water feed tank and connected that to the inlet of the pump. After some initial priming chattering, the pump smoothed out and ran great sucking water in that way. So that eliminates any thought of bad seals in my mind. I reconnected The existing inlet plumbing, being sure to tighten down the hose clamps on the flexible hose going from the water tank to the solid plumbing for the inlet. Pump runs nice and smooth on all high-pressure functions. So I'm kind of stumped and I'm just going to wait and see if the chatter comes back because I've had it smoothed out before and thought I had fixed it and then the chatter returns. It is a little bit confusing to me how the hose clamps on the flexible hose coming from the water tank loosen up after a short time but I guess we'll see…

 

[OurTown]

It is a little bit confusing to me how the hose clamps on the flexible hose coming from the water tank loosen up after a short time but I guess we'll see…

That is normal. The hose shrinks, and worm gear clamps do not keep them tight because they do not have spring tension. I always have to tighten worm gear clamps several months later.