Check The Cooling System - Volvo Penta MD7A Instruction Book

CHECK THE COOLING SYSTEM

The cooling system is functioning normally when the temperature warning lamp is out
and the buzzer is silent. Too high water temperature (the warning lamp is on and the
buzzer is sounding) can be due to the following reasons: Blocked water intake,
defective impeller or defective sea water pump carrier, faulty thermostat or temperature
sender. NOTE! When working on the cooling system, be careful and avoid water
coming into the boat.
CHECKING AND
CANGING THE
IMPELLER
COOLING SYSTEM
S-DRIVE MODEL 100S
CHECKS AND SERVICE
The impeller can be damaged by lack of
water among other things. Close the
bottom intake valve. Remove the sea
water pump cover. If it proves necessary
to replace the impeller, pull out the impel-
ler and the shaft as far as necessary to
reach the crew on the impeller hub.
NOTE! On earlier executions: Do not pull
out the shaft further than that, since the
sealing rings can be damaged when the
shaft is pushed back. Remove the locking
screw, (on earlier executions hold back
the shaft) pull off the impeller. Install a
new impeller, tighten the screw and push
the shaft back into position.
The carrier is defective if the impeller and
shaft can be turned. A new carrier can be
installed after having removed the pump.
Install the water pump cover, using a new
gasket. Open the bottom intake valve.
The cooling water intake for the cooling of
the engine is located in the lower gear
housing of the S-Drive. Check, while the
boat is on land, that the gillformed water-
intake and the hole in the lower edge of
the S-Drive are free from marine growth.
When inhibiting or when there is a risk of
temperatures below zero, drain off the
cooling water from the S-Drive and pump
by removing the cooling water hose from
the cock on the S-Drive.
NOTE! If draining with the boat in the
water, close the cock prior to start of
draining. Incorrect draining might easily
end up with a sunken boat. Do not forget
to open the cock prior to starting the
engine.
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