Reply To: CD12 strange cooling issue

[Don]

Joined just now as well….

Looks like the pump is working pretty well from the drill test.  But, there is no exhaust going through down there when you are pumping with the drill.  So, there is the possibility of some sort of air leak under the pump, pulling exhaust is a whole lot easier than pulling water.  I am also assuming the gearcase is buried deep in the water (over the gearcase/ex hsg joint) while running the engine in the bucket.

Was this engine new to you?  Did it ever pump water correctly?  If so, what changed since that time….  The wrong base gasket will defiinitely cause a water leak and possible overheat.  Are you sure the surfaces of the exhaust hsg and powerhead are in good shape, not corroded/damaged?

The water may be getting to the powerhead OK, but may not be able to circulate through or exit the powerhead.

Like others have suggested, you might want to install the powerhead/base gasket without installing the gearcase.  Now connect a small rubber hose to the copper water tube and adapt it to a garden hose.  Now turn the garden hose on just slightly to see if water circulates through the powerhead and exits from the exhaust relief….  If not, then there is some sort or restriction in the powerhead.

I know that on the 5.5/6hp models with the thermostat, water exits the block through a pesky right angle passage on the right side of the block on the bottom, this gets plugged relatively easily…