Evinrude 9.9 over heating

[driver0606]

Hello,
This is a new slant on a problem I have had some time with my 1988 Evinrude 9.9. The cylinder head and thermostat housing show few signs of sediment building up. I tried running the engine briefly in a tank with the thermostat cover off. There has been no thermostat fitted for some time. The "pee hole" shows a reasonable flow, but only a little water splatters out of the housing and none out of the hole in the front of the bulge in the underwater unit. If the engine is stationary and water is introduced into the thermostat housing from a hose, water runs well out of this hole.

It seems to me that either the water pump is working poorly, despite being recently overhauled, or there is a blockage at the top of the copper pipe that runs up from the water pump. The pipe itself is clear. If any body can comment on my theory it will be most appreciated.

 

[racerone]

In a test bucket the water must be 6" to 8" above the impeller.------Hard for those simple pumps used from 1974 to 2007 not the work.----They are that good and reliable !

 

[kbait]

With cylinder head off, blow air up the copper water tube while covering indicator nipple with your finger. If no/little air restriction, upper watertube grommet is not clogged. An overheat event can melt that grommet and restrict flow.. powerhead removal required to change it out. You’ll likely need a powerhead base gasket too..
But first,as racer said, confirm your barrel test is with pump submerged.
Good luck!

 

[racerone]

Install a thermostat !