Cooling

[WM. "Boo" Long]

I am interested in others experience with cooling & your solutions . My project is using a 1938 Muncie Neptune twin outboard motor for power . The fact that it is water cooled added plenty of complexity to the project . I used 1/2 of the radiator set for a 04 09 Honda CRF 250 , $70 Ebay , a very small but capable 12 v pump meant to be used for sous vide cooking ( hot water bath ) 29gph , 212 deg F , 1/4 " hose fittings , $16 Ebay , and a 4" 12 v computer fan , $16 Amazon . So far in bench tests it is running about 150 deg F in a 10 min idle . Not sure how this is going to work under load . Problem I see is the outboard wouldn't recycle the cooling water under normal conditions . I'm thinking I may need to add a couple quarts of coolant just so it doesn't get returned to the engine so quickly ? Anyone out there with water cooling experience ?

Any experience out there with water cooling

 

[indian22]

I think your onto something with adding coolant. Is a common coolant thermostat used? If so it's activation range is important. All measurements taken with coolant added & the water to coolant ratio is a factor. Are you reading heat at the head and also at the radiator inlet/ outlets. Fan thermostat sitting can be working counter to the actual water flow thermostat range. You've got a really nice build underway.

No factory outboard ever looked as good as the one pictured...regardless of the manufacturer!

Rick C.

 

[WM. "Boo" Long]

no thermostat in the original system , very simple old motor . the shiny motor is a pic of a complete one that I found on google . mine was not complete , & had no spark from the original magneto ( which is the death sentence for most of these old outboards ) so I used the original points & replaced the condenser which was unavailable with a capacitor , mounted up a twin output chevrolet coil , powered by a battery . plan to charge battery with tire driven dynamo .

 

[curtisfox]

I believe old stock car drivers used a washer of various sizes, instead of a thermostat. Restricts the flow but keeps it moving, just a thought. Experimentation would be needed.......Curt

PS like your bike.

 

[indian22]

I believe old stock car drivers used a washer of various sizes, instead of a thermostat. Restricts the flow but keeps it moving, just a thought. Experimentation would be needed.......Curt

PS like your bike.

Yeah Curt that's correct, just pulling the thermostat seemed a good idea back in the day, yet wasn't, some restriction was necessary. The outboard had continuous cooling reservoir, when converted to being dependent on re-cycled coolant that is never actually cool & forced through water jackets that weren't design for radiator use has to be somewhat problematical.

A couple of other things I'd mention. The electric fan is far more efficient when set up as an air puller rather than a pusher And will have an appropriate fan blade for that purpose, if the blade of either style is located on the wrong side of the radiator it won't move air properly. A fan with a well designed shroud around it functions far better too. You might try different rated radiator caps to regulate coolant flow psi.

Rick C.