2000 Mazda MPV ES Thermostat Testing
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THERMOSTAT 1. Remove and inspect thermostat for corrosion and proper seating of valve. If okay, suspend thermostat and thermometer in a 50/50 mixture of coolant and water. See Fig. 1 . DO NOT allow thermostat or thermometer to touch bottom or container. Heat water until thermostat begins to open. 2. Read temperature on thermometer. This is the initial opening temperature and should be within specification. Continue heating water until thermostat is fully open and note temperature. This is the fully open temperature. If either reading is not to specification, replace thermostat. PRESSURE TESTING A pressure tester is used to check both radiator cap and complete cooling system.
THERMOSTAT 1. Remove and inspect thermostat for corrosion and proper seating of valve. If okay, suspend thermostat and thermometer in a 50/50 mixture of coolant and water. See Fig. 1 . DO NOT allow thermostat or thermometer to touch bottom or container. Heat water until thermostat begins to open. 2. Read temperature on thermometer. This is the initial opening temperature and should be within specification. Continue heating water until thermostat is fully open and note temperature. This is the fully open temperature. If either reading is not to specification, replace thermostat. PRESSURE TESTING A pressure tester is used to check both radiator cap and complete cooling system.
Follow pressure tester
manufacturer instructions and test components as follows: Radiator Cap
Visually inspect radiator cap. If cap looks okay, connect pressure
tester to cap. See Fig. 2 . Pressurize tester to full radiator cap
specification. Replace cap if it fails to hold pressure. Cooling System
1. Turn ignition off and allow engine to cool. Ensure radiator if
filled to correct level. Remove cap and attach pressure tester to
radiator. Pressurize tester to full radiator rating specification. 2. If
pressure drops, check for external leaks. If no leaks are found, start
engine and allow to idle. If pressure builds up immediately, check cylinder head
and block for cracks. If pressure does not build up immediately, go to
next step. CAUTION: DO NOT allow excess pressure to build in cooling
system or damage may result. 3. Using pressure tester, pump cooling
system up to pressure specified on radiator cap. If pump gauge pointer
vibrates, compression or combustion leak into cooling system is
indicated. Isolate leak by shorting each spark plug wire to cylinder block. Gauge pointer vibration will stop or decrease when leaking cylinder is shorted.
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