Originally Posted by Kiwikat
One of our engines (yanmar 40) has recently developed an irritating leak, you know, not really bad but just enough to have to be topped up with coolant after several hours motoring. The mechanic
has reported that the leak is from the oil
cooler assembly and is due to old coolant. How can this be?
As well as antifreeze
, coolant contains corrosion
inhibitors, whose job is (obviously) to prevent corrosion
of all the engine
components which would otherwise happen when they are exposed to hot water
The problem is that the corrosion inhibitors get used up. An ordinary coolant should be changed every 2 years to renew the additives and OAT / HOAT coolants (Dexcool) every 5.
A common error is to assume that you don't need antifreeze when you never go to a freezing climate. You do, for the corrosion inhibitors.
As your oil cooler is a heat exchanger
between coolant and the engine
oil, it is possible that old coolant allowed it to corrode internally.
When was your coolant last changed?