369-05105-2 Tohatsu STARTER CASE

Visual Inspection Of The Cooling System
Cooling systems that are not regularly inspected and maintained may be the cause of increased engine temperatures. Make a visual inspection of the cooling system before you begin testing.
Personal injury can result from escaping fluid under pressure.If a pressure indication is shown on the indicator, push the release valve in order to relieve pressure before removing any hose from the radiator.
Check the coolant level in the cooling system. Read the two level indicators for the cooling system that are in the top of the radiator.
Inspect the cooling system for leaks.Note: A small amount of coolant leakage across the surface of the water pump seals is normal. This leakage is required in order to provide lubrication for the water pump seals. A weep hole has been machined in the water pump housing in order to allow this coolant/seal lubricant to drain from the pump housing. Intermittent leakage of small amounts of coolant from this hole is not an indication of water pump seal failure. Do not replace the water pump seals unless you find a continuous flow of coolant, or a large amount of coolant, that is leaking from the water pump housing. Refer to Disassembly and Assembly, "Water Pump" for the replacement procedure of the water pump seals.
Make sure that air flow through the radiator is not restricted. Look for bent core fins between the folded cores of the radiator. Also, look for debris between the folded cores of the radiator.
Inspect the fan drive belts for cracking or separation.
Inspect the fan blades in order to ensure that the blades are not damaged or bent.
Check the engine oil dipstick for signs of an internal coolant leak. The engine oil will have a milky appearance if contamination from the cooling system is present. If internal leakage is suspected, refer to "Testing The Radiator And Cooling System For Leaks" for instructions on pressure testing the cooling system.
Look in the radiator filler neck for air bubbles or combustion gas in the cooling system.
Inspect the pressure cap and the sealing surface. This surface must be clean and free of corrosion.Testing The Cooling System
Illustration 1 g00286266
Boiling point of waterTemperature and pressure work together. When a diagnosis is made of a cooling system problem, both the temperature and the pressure must be checked. Cooling system pressure will have an effect on the cooling system temperature. For an example, refer to the Illustration 1. This chart demonstrates the effect of pressure on the boiling point (steam) of water. Elevation also affects a pressure type cooling system. The chart also demonstrates this effect.
Personal injury can result from hot coolant, steam and alkali.At operating temperature, engine coolant is hot and under pressure. The radiator and all lines to heaters or the engine contain hot coolant or steam. Any contact can cause severe burns.Remove filler cap slowly to relieve pressure only when engine is stopped and radiator cap is cool enough to touch with your bare hand.Cooling System Conditioner contains alkali. Avoid contact with skin and eyes.
The coolant level must be within specifications prior to testing the cooling system. The engine must be cold and the engine must not be running. Ensure that the engine is cool and loosen the pressure cap in order to relieve any pressure from the cooling system. Slowly remove the pressure cap.The level of the coolant should not be more than 13 mm (0.5 inch) from the bottom of the filler neck. If the cooling system is equipped with a sight glass, the level of the coolant should be to the proper level on the sight glass.Test Tools For Cooling System
Table 1
Tools Needed    
Part Number     Part Name     Quantity    
4C-6500     Digital Thermometer     1    
8T-2700     Blowby/Air Flow Indicator     1    
9S-8140     Pressurizing Pump     1    
9U-7400     Multitach Tool Group     1    
Making contact with a running engine can cause burns from hot parts and can cause injury from rotating parts.When working on an engine that is running, avoid contact with hot parts and rotating parts.
Illustration 2 g00876179
4C-6500 Digital Thermometer Use the 4C-6500 Digital Thermometer for the diagnosis of both overheating and overcooling problems. This group can be used to check temperatures in several different parts of the cooling system. Refer to the testing procedure in Operating Manual, NEHS0554.
Illustration 3 g00286269
8T-2700 Blowby/Air Flow Indicator