Re: [Amel Yacht Owners] Re: Onan Raw Water Cooling System Maintenance


Actually, I am not sure and had a lot more questions. My partial answer was for the raw water side. It is unusual to have to flush the coolant side, but certainly possible.

People sometimes forget about the exhaust manifold when disassembling and cleaning, and usually concentrate on the heat exchanger and elbow. I have seen some ugly exhaust manifolds, blocked by carbon. 


CW Bill Rouse
Admiral, Texas Navy
Commander Emeritus

Amel School
720 Winnie St
Galveston Island, TX 77550

+1(832) 380-4970

On Sun, Nov 25, 2018 at 9:37 AM greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:


Are you sure he is talking about the raw water side? That sounds more like an engine block freshwater side cleaning process. The Onan raw water system is really simple and can not be setup to recirculate while running.

A pump, hoses, heat exchanger, and exhaust elbow. It is also not made of things that "rust". The pump is bronze, and the heat exchanger is copper-nickel. They can corrode, if the zinc is not maintained, but they typically do not clog from this, they just get thinner. The can clog from biological fouling if run a lot or from salts precipitating from seawater if not run often.

The exhaust elbow can not be cleaned effectively in-situ, it really needs to be removed if it is clogged or fouled.

The only process I know of to clean in place requires removal of the pump impeller, then pumping a phosphoric acid based cleaner (like BarnacleBuster) through the pump and heat exchanger. This bypasses the exhaust elbow, and is effective, but does not involve running the engine at all.

The Onan system is simple enough, if my heat exchanger was in need of serious cleaning, I’d take it off and clean it by hand.

Bill Kinney
SM160, Harmonie
Fort Lauderdale, Fl, USA

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