Technical data

5. SEA WATER PUMP IMPELLER REPLACEMENT
The following instructions are general and indicative only. Specific instructions where applicable may
be packaged with your replacement impeller.
a. Remove the front cover gasket taking care to salvage the gasket.
b. Remove the impeller by pulling straight outwards, parallel to the pump shaft. This is best
done with a pair of pliers applied to the impeller hub.
c. Coat the replacement impeller and the chamber into which it mounts with grease.
d. Carefully align the impeller key way, or other locking mechanism, with the shaft. Take care
that all the impeller blades bend in the same direction and trailing.
e. Inspect the front cover for wear. A worn front cover should ultimatelybe replaced. Sometimes
it can be reversed as an emergency measure, but not when stamped markings would break
the seal between the cover and the impeller blades.
f. Reinstall the end cover with a new gasket.
g. Be doubly sure to check quickly for sea water flow when starting the engine. The absence of
flow indicates that the pump may not be priming itself properly. This situation must be
investigated immediately or damage to the new impeller will result from overheating.
6. ENGINE FRESH WATER
It is preferable to fill your engine with a 50% antifreeze-water mixture. This precludes the necessity of
draining coolant in the winter. Since most antifreezes contain preservative agents of one kind or another,
rusting within the engine is minimized. Also, the antifreeze mixture boils at a higher temperature than
water, giving cooling system "head room".
When draining the engine, open the pressure cap first to relieve the vacuum created by draining.
7. FILLING THE FRESH WATER SYSTEM
It is very important to completely fill the fresh water system before starting the engine. It is normal for
air to become trapped in various passages so all high points must be opened to atmosphere to bleed
entrapped air. When an engine is started after filling with coolant, the system may look deceptively full
until the thermostat opens. At this time when water flows through the external cooling circuit for the first
time, pockets of air can be exposed and rise to the fill point. Be sure to add coolant at this time.