On 3/2/2011 4:50 PM, dmo@omd. wrote:
hi,

i'm wondering where the water intake is for the cooling system on outdrives and
outboards. it seems that it should be far enough up that it wouldn't be in much
danger of sucking up sand, but someone recently warned me to be a lot more
careful about not starting an engine when the prop is resting on the sand. how
low is the intake?

Depends on the motor too. Optimax ProXSs are particular susceptible to
plugging. They have two issues.

One if the motor does not come up to full temperature before running it
up to WOT in cold water it is at risk of seizing a piston. If the motor
picks up sand and gravel at the wrong time it can stick in the
thermostats preventing them from closing. If they do not close the
engine may not come up to full temperature the next time it cools down
and is started.


Also, the water bypass (****er) circuit is responsible for cooling the
air pump. The ****er exit port has a sharp bend internally and small
particles tend to stick at that point closing off the hole. When this
happens water does not flow through the air pump and you get an air pump
overheat warning.

Since a lot of (most?) of this series of motor has low water pickups to
maintain pressure at higher running heights of the motor, starting with
the prop on or near sand is almost guaranteed to cause it to pickup sand
and gravel.

I am sure other motors may have similar or different issues with sand
and gravel.