Cooling system pressure?

[1945dave]

I also have had various experience in racing conditions with lost cooling. That is why all my helicopter motors are out runners. Makes a big difference. I don't understand why we don't see more water-cooled outrunner motors than the few small 36 sizes.

Thanks,

Dave

[Prop-a-Gator]

How much pressure do you think these things are under?
Tested a cooling system with a mouthfull of water through the intake line, plugging the exit - no leaks.
Run the boat and end up with enough water in the hull to make me nervous.
Tried a bunch of things thinking it was coming up the stuffing tube, no solution.
Tested the cooling system again under higher pressure using Tony's patented pressure tester (hose and sink adapter)and the cooling can leaks like a sieve!
Easy fix but I was surprised at how much pressure it took for the leaks to show up.
Was really perplexed on this one, was about convinced it was coming up the stuffing tube but there was no oil in the hull, even tried straight grease to plug the tube. LOL even tapered a drive dog to eliminate the flat face thinking this may be causing the problem.
Not my area of math and physics classes were many,many years ago. How much pressure do you think we have going on in these things?
At least I know my system has good flow! Must if it can generate the amount of pressure it took for the leaks to show up!
Plain old rudder pickup, completely stock, no opening of the intake hole at all.

I know you've pretty much solved your leak but I had a couple of questions out of curiosity.
Assuming you did not fill your cooling circuit and purge any air before doing your initial leak test, is it possible you were pushing air out of your leak point and didn't notice? Did the water in your mouth wind up going into the cooling circuit, or were you left with a mouth full of water and a blue face?

Also, what was your final fix? I didn't see where you mentioned what you actually did when you found the leak. I know it's a little off topic from your original question, but just trying to gain some knowledge.

[m4a1usr]

I also have had various experience in racing conditions with lost cooling. That is why all my helicopter motors are out runners. Makes a big difference. I don't understand why we don't see more water-cooled outrunner motors than the few small 36 sizes.

Thanks,

Dave

The answer to that is easy. Its much harder to make an effective cooling system for an outrunner with a water jacket compared to an inrunner. Look at the curent designs used. Even the manufacturers of the motors cannot make a decent method of cooling them. By design the heat generation system is embeded deeper into the mass. The rotor maybe outside of the windings but the winding core is where the heat is contained. Neither inrunner or outrunner designs offer decent solutions to removing the heat out of the iron core where it builds over time. However what an outrunner has in favor is moving air over the mass due to surface area of rotational parts, where as even the inrunners with built in fans lack the same CFM capability.

John

[ozzie-crawl]

My cooling check consists of using a large syringe. Disconnect hose from rudder and push over syringe end,add a cable tie. Push water threw till it fills the lines (water comes out the outlet) Add more water to syringe if needed. Block outlet and use syringe to create pressure.
Not sure how much pressure is behind this method. Usually you see the hose swell. Has always worked well for me.

[siberianhusky]

LOL no system was purged before I tried the blue face method, Kind of a habit, air compresses liquid doesn't.
Just did a bit of silicon on both ends after I removed and replaced the cooler to make sure the rings were fine etc, although it was just leaking from one end.
BTW It's the aluminum cooler on one of the most popular spec motors.
I did see a thread quite a while ago where somebody was directly cooling an outrunner on a tunnel hull by shooting the water right into the rotor, never heard much more about it.