Keel cooler sealing advice

Hi all, I am after some advice I have a Nanni 55 hp engine that is designed for keel cooling, the manufacture recommends 1.85 sqr/mtr of surface area for effective cooling at >18 deg C water temp, and as I will be sailing mainly in the tropics. I have built one side, and together it will have about 1.95 sqr/mtrs of surface area and hold around 20 ltrs of coolant total (inc engine). I have built one side and have pressure tested it to 20psi the overflow/heat expansion cap is pressure rated to 1bar/14.5 psi, now in over an hour it lost 0.5psi through two small pinprick holes that I can not get too to weld them effectively. Any advice on how I could seal them. Was thinking of filling it with a thinned oil base paint pressurising it and then draining and washing the paint out??? each cooler side hold around 4 ltrs. Any advice would be appreciated.

Cheers

Cal

 

2C epoxy adhesive can seal the pinholes if you can reach them with a thin object and the holes are dry. If you have access to a pump, pull some vacuum so the adhesive gets in all the way.

If you have no access at all, use the stuff that seals car radiators.

 

Cheers CDK :idea:

 

The engine will overheat in tropical shallow waters. They can get to over 30C. Also, any coating you put in the heat exchanger will lower its heat transfer rating.