I have a new Yanmar
4JH4TE that was installed in my boat roughly a year ago. Since installation
, the coolant
overflow tank level has been consistently falling approximately one inch every 20 hours of use. There are no signs of external leaks
anywhere in the cooling
system, including my hot water
heater and elsewhere. There are also no signs whatsoever of water
ingestion by the engine
. I have added approximately one gallon of cooland over the last year.
My installer came out and performed a coolant
system pressure check. While there was a very slight drop in pressure over about 15 minutes, we believe that to be caused by leaks
in the pressure check apparatus. The technician indicates that the drop in coolant level could be caused by an air bubble in the water heater coolant loop that is slowly being replaced by coolant. His recommendation is to see if the problem disappears over time. He also indicates that this problem can be caused by a leak in the hot water heater heat exchanger
, but the coolant level in my previous engine
(4JH3TE) never dropped at all and there doesn't appear to be coolant in the hot water. It would also be quite a coincidence if my water heater failed exactly at the time the new engine was installed. No corrective action was taken, and I am somewhat skeptical that the indications would continue for this length of time. Any recommendations or advice on nailing the cause down would be appreciated.