[C320-list] Leaking Macerator Pump

[resloat]

I have hull 894 (2002) and recently noticed a slight leakage to the bilge from the macerator pump (Jabsco Model 18590 Series) which is attached to the holding tank and a thru-hull.   It was leaking in the area where a two piece plastic housing holds the impeller and chopping blade.  After finding the leakage from the pump, I thought that maybe the pump had cracked from freezing water over the winter storage, but that was not the case.

I believe a macerator pump is installed on all 320s and for inland sailing the dealer disconnects the electrical connections for the pump so it is inoperable to meet USCG regulations.  A USPS Vessel Safety Check on my boat resulted in the inspector telling me to wire the thru-hull from the macerator pump closed as that is additional assurance the USCG would not find a violation.  Overboard discharges of head waste is illegal except a few miles offshore.  This pump had never been used.

The pump takes a while to get out as there are two 1 1/2 ID wire re-enforced hoses and a small 1 inch hose connected to the macerator pump.  You have to really work hard to break them loose from the plastic fittings on the pump without cutting the hoses.  Make sure you pump out the holding tank and flush it out a few times with rinse water to make the job a little nicer.

The pump had very little residue in it after a pump out.  The leaks were at two very thin gaskets that seal a large metal wear plate on either side located where the two piece plastic housing is mated.  When the pump was disassembled these two gasket looked like they had dissolved as there was little left of them in some areas resulting in leakage.  You can get a rebuild kit for this pump which includes the entire plastic housing and internal parts or replace the entire pump for about the same prices.  I was unable to find just the gaskets for sale so I made my own.

Everything else in the pump looked OK so I just cut out gasket material from 3-4 mil heavy duty plastic sheeting (almost as thick as shrink wrap) to match the two gaskets by using the large wear plate and part of the plastic housing as templates.  I had some heavy duty automotive gasket material but it looked like it might leave too much clearance between the impeller and the large metal wear plate next to the impeller.  Four holes were punched in the new gaskets to match the studs holding the pump together and the pump was reassembled. I used a little lubricant on the hoses so the pump would be installed a little easier.

So far after 3 months no leakage from the repair.  Except for the hassle of removing the pump and the thought of dealing with head work this is a fairly straight forward repair and saved at least $70 for the rebuild kit.

Bob Sloat
S/V Savannah 894 (2002)