Leaks? None here. Fixin' the leaks and preventing future ones was essential. The king-nipples that fix to the 1” hoses are NPT thread. They’re screwed into adaptors to British standard pipe thread on the engine – I got steel adaptors rather than brass. Because BSP is different from NPT the adaptors prevent a significant leak source – incompatible threads. The hoses are from NAPA. The tank is “open” in the sense that it ventilates to atmosphere, but once the initial dissolved gasses vented on heating I have never noticed any visible vapor release through the vent-filter. The coolant mix is one tube of aluma-seal, a pint of soluble oil to 65 gallons of water and 3 quarts of nalcool. All this stuff cost about 25 dollars at NAPA. The dinural carry-over of heat seems to prevent frost danger, but if the machine were in a colder climate I’d have dumped in 20 or more gallons of glycol. Considering the lack of containment it would be propylene glycol – we drink the water around here and don’t want trouble with groundwater pollution. The static pressure at the coolant inlet is about 3 psig; it’s a tall tank. It’s got a 190 thermostat out a Chrysler. Isolation gate valves are located at the weldalets on the tank breast. The setup uses steel and iron throughout except for the gate valves, which are brass. The tank and engine are electrically bonded. There is potential for the gatevalves to corrode due to their zinc content, and I expect that they are slowly corroding. They act as sacrificial anodes, especially the upper valve, which is generally fairly hot, but the corrosion rate is very low due to the resistance of the coolant. This coolant mix is not too much different from the coolant you’d use in a machine shop, so I do not expect that an internal leak would cause any damage unless you let it go. There’s a vertical vinyl ¼” tube on the side of the tank about 5 feet long so at every start you can see if the coolant level has changed. (Of course a substantial leak would be obvious anyway.) Anyway the brass valves are only $10.00 each and when one does need changing it’s not going to be a big deal. There’s a brass hose bib drain valve at the tank hemispherical bottom and I paid attention to making a smooth transition there so crud would collect in the drain nipple. The hose bib is capped for security. If there were busybodies hereabouts I’d take the handles off the isolation valves too. Cooling system efficiency does not seem to me to be a material consideration with this engine because it uses no crankshaft power to circulate coolant and no crankshaft power to blow air through a radiator. Because it’s a stationary engine weight isn’t a factor (it’s in the neighborhood of 4 tons, counting the foundation – so who cares?). If it ever overheats, which seems very unlikely, we will consider adding a heater core or a fan or just more tank – more tank being the “best” in my opinion. This one’s about 65 gallons with a lot of surface area, tall n’ skinny, but I have 120 gallon tank, cut open, that would fit almost as well. Tanks are free, by the way – the well driller and the propane guy both have piles of “condemned” steel tanks that are workable for people who know what they’re doing. Welding on tanks, especially fuel tanks, is a matter between you and God. I’ll do it, but only with proper precautions, and I don’t take chances on explosions and fires.
Seems to me that the main thing to observe with respect to water treatment with these engines is to prevent freezing in the jacket, the secondary thing is to minimize cavitation damage – that’s what the nalcool’s for, and the last thing is to use only ferrous materials so that the galvanic potential is about equal throughout the cooling water system – if I could have bought steel gate valves cheap I would have – and I have a weather-eye out for some “free” ones I might get from the ‘fitters on a job….