Rotax 582 gray head cooling system mod idea

[109jb 181]

Both the current Kitfox 4 project I have and my previous Kitfox 4 were/are powered by gray head Rotax 582s. I know from my former airplane that keeping the water temperature up in winter operations was difficult especially when descending from altitude. Covering the radiator helped but did not eliminate this problem to the point that doing takeoff and landing practice in cold temps meant landing and then waiting again for water temp to come back up before taking off. 

I know the Blue head 582 had the cooling system modified to allow faster warmup and prevent this type of cool down situation. I also used to own a 2-up snomobile that had a 580 in it and it had the bypass hose like the blue head 582. Looks to me like all they really did was put a second inlet on the water pump, and another outlet at the top of the head. What I am thinking about is shown in the picture below. I believe this would essentially make a gray head operate like a blue head in terms of cooling. I would machine a housing to locate the stock rotax thermostat in the hose rather than the outlet neck. On my previous kitfox I had planned to do basically this with a heater core in the middle of that red line between the thermostat and the pump inlet but never got around to it. On this airplane there is no heater currently installed and no room because of the fuel tank for hot water heat, so I am going to make a heat muff and use exhaust heat for the cabin.  What do you more experienced 2-stroke flyers think.

[109jb 181]

Never mind. After more research it appears that the thermostat, when it opens to allow flow to the radiator, it has another disk to close off the flow through the bypass hose.

[Dusty 126]

The Grey top has a single action thermostat  the blue a two way ,a much better system but the single action seems to work ok(not as cold here).I am assuming your Grey has a thermostat? If it still isn't holding heat ,the steam vent at the front of the head maybe be bypassing too much coolant. Solder this up and drill a small hole. This is usually the easiest  fix.

[Lorax 0]

Would replacing the grey cylinder head with a blue head work..

Is there any other physical difference between the two..

[109jb 181]

Would replacing the grey cylinder head with a blue head work..

Is there any other physical difference between the two..

Yeah I think that would work, but probably not worth the trouble