Fresh water pump cycling

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HowLin's picture
HowLin
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Posts: 355
Fresh water pump cycling

The water pump cycles for about 1 sec every 15 min or so.  I've tightened all the hose clamps I can get to - only one I can't find is the starboard tank outlet to pump.  I can get to the fitting on top of the tank (I think that's the vent?) but can't seem to find the tank outlet...?

---- Howard & Linda Matwick ----

--- S/V "Silhouette" - Nanaimo, BC ----

--- 1999  C36 MkII  #1776 M35BC ---

mutualfun's picture
mutualfun
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Joined: 6/25/07
Posts: 454

Howard. You need to look on the pressure side of the pump. Some place your loosing just enough water to create a pressure drop. Which in time kicks the pump on.

Randy Sherwood
Mutualfun 1990 # 1057
T/R W/K M35a
Home. Charlotte, Mi.
Boat. St Augustine,Fl.

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TomSoko
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Posts: 978

Howard,
It's also possible that you have a speck of dirt in one of the internal diaphrams in the pump, which would allow water to leak between chambers, reducing the pressure, and causing the pump to cycle.  That happened to me a few years back, and it was a bear to find. Just a thought.

Tom Sokoloski
C36/375IA Past Commodore
Noank, CT

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jgibbons727
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Posts: 7

I had a similar problem last year. It turned out to be a hairline crack in a plastic elbow, but I found it by putting some red food coloring in the tank. Then I followed the tiny trail of red from the bilge back toward the offending component.

Jim Gibbons
S/V Just Add H2O #1503
Chicago-Lake Michigan
1995 C-36 MKII TR/SK M35AC

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Channel Islander
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Posts: 378

Howard - I did what you did, tightening and even replacing the hose clamps everywhere. I put dry tissue paper under each one to see if there was any leakage at all. Didn't help. In the end the cause revealed itself as a microscopically small leak through the galley sink faucet. Try as I might, after I was sure that was the culprit, I couldn't observe the water dripping. But when I replaced the washer in the faucet, the cycling stopped.

 

Nick Tonkin
*Former* Website Administrator, C36/375IA
*Former* owner, C36 tr/fk #255, Santa Barbara, CA

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clennox
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Posts: 212

I looked and looked and finally found a small leak at the cockpit shower. I had forgotten that water was plumbed aft.

Chuck Lennox
97 MKii Ventura Ca
Island Girl Hull #1611

dpower
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Joined: 6/20/08
Posts: 239

In addition to checking all of the plastic elbows and other fittings in the pump area I would put down paper towels under all of that to see if there is a leak there and where.  It sure helped me.  CheckIng the inside of the pump chamber is also a good idea.

David S. Power
Two If By Sea #1687
Burnt Store Marina
Punta Gorda, FL

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Chachere
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Posts: 826

Had the same problem, and looked everywhere and couldn't find the leak -- until I discovered that the expansion tank had a pinhole leak in it (they are made out of ordinary painted steel and will eventually rust through).  

Matthew Chachère
s/v ¡Que Chévere!
(Formerly 1985 C36 MKI #466 tall rig fin keel M25)
2006 Catalina Morgan 440 #30.
Homeported in eastern Long Island, NY

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newguy
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Joined: 8/1/11
Posts: 408

Four common causes, from most likely to least:

  • A leak downstream of the pump
  • Defective pressure sensor in the pump
  • Pump valves not seating and allowing pressure side to bleed back into inlet side.
  • Leakage from the FW system into the engine cooling system via the water heater.

 

Nick Caballero
Retired C36/375IA Mk II Technical Editor

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mike37909
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Joined: 1/17/13
Posts: 161

Mine did the same thing and after finding no leak I disconnected all plumbing and valved it off and it still did it.  It was obviously not leaking.  Then I noticed the set screw that sets the pressure.  I turned it down some and  no more cycling. 
 

Catalina 36 MK1
1984 Hull #306

 

HowLin's picture
HowLin
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Joined: 1/12/12
Posts: 355

Yikes; one of those "could be a million things" scenarios...  more checking to do.  
Thanks for all the suggestions!

Edit...   turned out to be a defective fitting in the cockpit shower....  thanks to everyone for the suggestions.

---- Howard & Linda Matwick ----

--- S/V "Silhouette" - Nanaimo, BC ----

--- 1999  C36 MkII  #1776 M35BC ---

pierview
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Joined: 9/27/09
Posts: 606

Re  Mike's comment on the set screw (assuming we're talking about  a Shuflo pump), I had problems with my pump & spoke to the Shurflo tech people.If its a pre-2008 pump, there is no set screw. They added it later  on. I just (yesterday) replace my 5 GPH pump because it continued to kick off my circuit breaker and the new one does not have a set screw I could find either.

Chuck Parker
HelenRita 2072 Mk II
2002 Tall Rig - Winged Keel
Atlantic Highlands, NJ

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andreshs1
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Joined: 4/4/13
Posts: 100

Hi

I had a similar problem since I bought the boat, I guess this was the same with the PO.

I just replaced the pump and no more nuisance.

regards
Andres

Andres & Arantzazu
S/V "Carpe Diem"
Hull: 1773
1999 C36 mkII
Hong Kong
http://www.abclubhk.com/

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