Boater,

I'm assuming this is a sterndrive. Also assume the drive water pump
provides the pressurized cooling water flow and that the engine is raw water
cooled. The engine mounted pump is simply for circulation of the cooling
water.

There are a couple of possibilities: First and most obvious is that the
drive pump requires a new impeller, particularly if the engine was run while
the drive was out of the water. Second is that a hose may have kinked.
Third is that the drive has sucked something into the water passages and
flow is now restricted.

Try this. Reinstall the thermostat. Put the muffs on the drive and supply
water to the unit. Is water now flowing out of the prop hub? Now remove
the manifold drain plugs and allow the water to flush until it runs clear.
Repeat with the block drain plugs. If the elbows have drains repeat there.
Remove the engine mounted water circ pump plug and repeat the process. Also
remove the water hoses on the engine and flush them. If there is water
flowing out the prop hub start the engine after replacing all plugs and
connecting all hoses. Don't run the engine above idle speed. If after a
few minutes the water coming out the hub becomes hot but not steaming the
temp gage should be above the cold mark but not above normal. If that is
the case try an in the water test. If the engine begins to overheat it's
time for an impeller kit in the drive.

Butch
"boater101" wrote in message
oups.com...
Hi all,

Trying to diagnose my 1993 OMC Cobra 4.3L water flow troubles. The
motor starts and runs well, but no water flows thru the engine. I
removed the thermostat to rule out whether this could be the trouble.
Even with the thermostat out, there still is no water flow. Short of
taking out the water pump next, is there anything else I can try before
I target the water pump?


thx in advance,

adym