Yamaha MT-03 - Service manual > Cooling system

Radiator

Checking the radiator

1. Check:

• Radiator fins

Obstruction → Clean.

Apply compressed air to the rear of the radiator.

Damage → Repair or replace.

NOTE:

Straighten any flattened fins with a thin, flathead screwdriver.

2. Check:

• Radiator hoses.

  Cracks/damage → Replace.

3. Measure:

• Radiator cap opening pressure

Below the specified pressure → Replace the radiator cap.

Radiator cap opening pressure 110.0-140.0 kPa (1.10-1.40 kg/cm2, 16.0-20.3 psi)

a. Install the radiator cap tester "1" and radiator cap tester adaptor "2" and radiator cap tester adaptor "3" to the radiator cap "4".

Radiator cap tester 90890-01325

Radiator cap tester adaptor 90890-01352

Radiator cap tester adaptor 90890-01497

b. Apply the specified pressure for ten seconds and make sure there is no drop in pressure.

4. Check:

• Radiator fan

Damage → Replace.

Malfunction → Check and repair.

Installing the radiator

1. Install:

• Radiator inlet hose "1"
• Radiator outlet hose "2"
• Hose clamps "3"

NOTE:

Install the radiator inlet hose and radiator outlet hose so that each hose contacts the respective projection "a".

2. Fill:

• Cooling system (with the specified amount of the recommended coolant)

3. Check:

• Cooling system

Leaks → Repair or replace any faulty part.

a. Attach the radiator cap tester "1" and radiator tester adapter "2" to the radiator.

Radiator cap tester 90890-01325

Radiator tester adapter 90890-01496

b. Apply 100 kPa (1.0 kg/cm2, 14.2233 psi) of pressure and make sure there is no drop in pressure.

4. Measure:

• Radiator cap opening pressure.

  Bellow the specified pressure → Replace the radiator cap.

Thermostat

Checking the thermostat

1. Check:

• Thermostat "1" Does not open at 71-85 ºC (159.8-185 ºF) → Replace.

a. Suspend the thermostat in a container filled with water.

b. Slowly heat the water.

c. Place a thermometer in the water.

d. While stirring the water, observe the thermostat and thermometer's indicated temperature.

1. Thermostat

2. Thermometer

3. Water

4. Container

Fully closed

Fully open

NOTE:

If the accuracy of the thermostat is in doubt, replace it. A faulty thermostat could cause serious overheating or overcooling.

2. Check:

• Thermostat cover
• Thermostat housing (cylinder head) Cracks/damage → Replace.

Installing the thermostat

1. Install:

• Thermostat "1"
• O-ring "2"
• Thermostat cover "3"

Thermostat cover bolts 10 Nm (1.0 m*kg, 7.2 ft*lb)

NOTE:

• Install the thermostat with its breather hole "a" facing up.
• Lubricate the O-ring with a thin coat of lithium-soap-based grease.

2. Install:

• Radiator inlet hose "1"
• Hose clamp "2"

Hose clamp Max 3 Nm (0.3 m*kg, 2.2 ft*lb)

NOTE:

Install the radiator inlet hose "1" so that it contacts the projection on the thermostat cover "a".

3. Install:

• Copper washer
• Coolant temperature sensor

Coolant temperature sensor 18 Nm (1.8 m*kg, 13 ft*lb)

CAUTION:

Use extreme care when handling the coolant temperature sensor. Replace the sensor if it is dropped or subjected to a strong impact.

4. Fill:

• Cooling system (with the specified amount of the recommended coolant)

5. Check:

• Cooling system

Leaks → Repair or replace any faulty part.

6. Measure:

• Radiator cap opening pressure

Below the specified pressure → Replace the radiator cap.

Water pump

Disassembling the water pump

1. Remove:

• Water pump seal "1"

NOTE:

Tap out the water pump seal from water pump housing in the direction of the arrow shown.

2. Water pump housing

2. Remove:

• Bearing "1"
• Oil seal "2"

NOTE:

Tap out the bearing and oil seal from water pump housing in the direction of the arrow shown.

3. Water pump housing

3. Remove:

• Rubber damper holder "1"
• Rubber damper "2" (from the impeller, with a thin, flat-head screwdriver)

NOTE:

Do not scratch the impeller shaft.

Checking the water pump

1. Check:

• Water pump housing cover "1"
• Water pump housing "2"
• Impeller "3"
• Rubber damper "4"
• Rubber damper holder "5"Cracks/damage/wear → Replace.

2. Check:

• Water pump seal
•  Oil seal Cracks/damage/wear → Replace.

3. Check:

• Bearing Rough movement → Replace.

4. Check:

• Impeller shaft gear Pitting/wear → Replace.

5. Check:

• Water pump outlet pipe
• Radiator outlet hose
• Water jacket inlet housing Cracks/damage/wear → Replace.

Assembling the water pump

1. Install:

• Oil seal "1" (into the water pump housing "2")
• Bearing "3"

NOTE:

• Before installing the oil seal, apply tap water or coolant onto its outer surface.
• Install the oil seal with a socket that matches its outside diameter.

2. Install:

• Water pump seal "1"

CAUTION:

Never lubricate the water pump seal surface with oil or grease.

NOTE:

• Install the water pump seal with the special tools.
• Before installing the water pump, apply Yamaha bond No.1215 "2" to the water pump housing "3".

Mechanical seal installer "4" 90890-04132

Middle driven shaft bearing driver "5" 90890-04058

Yamaha bond No.1215 90890-85505

Push down.

3. Install:

• Rubber damper "1"
• Rubber damper holder "2"

NOTE:

Before installing the rubber damper, apply tap water or coolant onto its outer surface.

4. Measure:

• Impeller shaft tilt

Out of specification → Repeat steps (3) and (4).

CAUTION:

Make sure the rubber damper and rubber damper holder are flush with the impeller.

Impeller shaft tilt limit 0.15 mm (0.006 in)

1. Straightedge

2. Impeller

5. Install:

• Impeller shaft assembly "1"
• Washer
• Pin
• Impeller shaft gear
• Circlip

NOTE:

After installation, check that the impeller shaft rotates smoothly.

Installing the water pump

1. Install:

• Water pump outlet hose "1"
• O-rings
• Water pump outlet pipe (to the water pump assembly)

Water pump outlet pipe bolts 10 Nm (1.0 m*kg, 7.2 ft*lb)

• Hose clamps "2"

Hose clamp Max 3 Nm (0.3 m*kg, 2.2 ft*lb)

WARNING

Always use new O-rings.

NOTE:

• Install the water pump outlet hose so that it contacts the projection "a" on the water jacket joint.
• Before installing the water pump outlet pipe, lubricate the O-rings with a thin coat of lithium- soap-based grease.

2. Install:

• Gasket
• Water pump assembly

Water pump cover bolts 10 Nm (1.0 m*kg, 7.2 ft*lb)

• Water pump cover

Water pump assembly bolts 10 Nm (1.0 m*kg, 7.2 ft*lb)

3. Install:

• Radiator outlet hose "1"
• Hose clamp "2"

Hose clamp Max 3 Nm (0.3 m*kg, 2.2 ft*lb)

NOTE:

Install the radiator outlet hose "1" so that it contacts the projection "a" on the water pump cover.

4. Fill:

• Cooling system

(with the specified amount of the recommended coolant)

5. Check:

• Cooling system

Leaks → Repair or replace the faulty part.

6. Measure:

• Radiator cap opening pressure.

  Below the specified pressure → Replace the radiator cap

See also: