I have developed a small coolant leak in the #2 rotor of my renesis. It seems to be limited to the engine sitting for long periods of time. I discovered it when checking the plugs after the engine had not been started for a couple of months while fitting the new supercharger. The leading plug was wet. Pulling the prop through sprayed some coolant out of the leading plug hole. I checked the fluid level and it was a little lower than I remember.  I added some water and marked the level on a stick for reference. The next day I check the level and found no measurable drop.  Since I had just installed the larger supercharger I decided to do a few ground runs and check the coolant for leaks and keep a close eye on the water pressure. I made several ground runs and everything was normal. The plane was schedule for body work at a paint shop as soon as I could make the 50 mile trip. I waited a few days and rechecked the fluid level. Again no measurable drop.  I then made three short flights around the airport to check out the new supercharger and kept a close eye on water pressure and temps. Everything was normal. After checking the coolant level the next day I made the trip to the painters. The flight was normal but the pilot was a little nervous.

 

 The plane has not been started for six weeks and it sprayed maybe two tablespoons of coolant when pulling the prop through. I did not have my measuring stick but I could tell coolant level was a little lower then the last time I had checked it.

 

I will most likely have to replace the o-ring. I overheated one time last summer during a ¾ mile uphill taxi and OAT above 100F. The tarmac temps could have been 115F. I shut the engine down when the coolant temps got to 225F but they kept climbing. I think it took two gallons of water to refill the system.

 

 Since my water pressure is normal and does not leak down rapidly after shutdown is it possible the engine heat is sealing the O-ring ?  Maybe I just need to re-torque the big bolts.

 

Bobby Hughes

RV10 Renesis