BRP Johnson 4HP - Operation; Water Cooling System

6-40
POWERHEAD
OPERATION
OPERATION
Water Cooling System
The water cooling system includes the gearcase water pump, the water supply tube, the powerhead
water passages and the thermostat.
This system cools both the powerhead and exhaust and is shown in schematic from below.
If overheating occurs, the components of the cooling system must be inspected for blockage, corrosion
build-up or component damage.
[Component inspection] [Refer to page]
Water pump / Impeller ............................................ 8-8
Water tube .............................................................. 7-10
Thermostat.............................................................. 6-31
Cylinder head ......................................................... 6-12
Cylinder block......................................................... 6-21
CYLINDER
BLOCK
CRANKCASE
DRIVESHAFT
HOUSING
EXHAUST OUTLET
CYLINDER
HEAD
INTAKE
MANIFOLD
When open
THERMOSTAT
EXHAUST
WATER JACKET
DRIVESHAFT
HOUSING
WATER TUBE
WATER PUMP
WATER INTAKE
PILOT WATER
HOLE
WATER