823813 25 Mariner TUBING

Visual Inspection Of The Cooling System
Cooling systems that are not regularly inspected are the cause for increased engine temperatures. Make a visual inspection of the cooling system before a test is made with test equipment.
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 indicators for the coolant level in the top of the radiator.
Look for leaks in the system.
Look for bent core fins or for trash between the folded cores of the radiator. Ensure that air flow through the radiator does not have a restriction.
Check for damage to the fan blades.
After the engine is cool, remove the filler cap slowly. This will allow any pressure out of the cooling system. Inspect the filler cap and the surface that seals the cap. This surface must be clean and the seal must not be damaged.
Check the pressure relief valve. Relief pressure of the valve is 105 to 125 kPa (15 to 18 psi).
Look for air or combustion gas in the cooling system.Testing The Cooling System
Illustration 1 g00286266
Boiling Point Of WaterRemember that temperature and pressure work together. When a diagnosis is made of a cooling system problem, temperature and 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 will show the effect of pressure on the boiling point (steam) of water. This will also show the effect of height above sea level.Test Tools For Cooling System
Table 1
Tools Needed     Quantity    
4C-6500     Digital Thermometer     1    
8T-2700     Blowby/Air Flow Indicator     1    
9U-7400     Multitach     1    
9S-8140     Pressurizing Pump     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 g00286267
4C-6500 Digital Thermometer The 4C-6500 Digital Thermometer is used to test for any overheating conditions or for any cooling 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 The 8T-2700 Blowby/Air Flow Indicator is used to check the air flow through the radiator core. Refer to the testing procedure in Special Instruction, SEHS8712.
Illustration 4 g00286276
6V-3121 Multitach
Steam or hot coolant can cause severe burns.Do not loosen the filler cap or the pressure cap on a hot engine.Allow the engine to cool before removing the filler cap or the pressure cap.
Check the Filler Cap
One cause for a pressure loss in the cooling system can be a defective seal on the filler cap.
Steam or hot coolant can cause severe burns.Do not loosen the filler cap or the pressure cap on a hot engine.Allow the engine to cool before removing the filler cap or the pressure cap.
After the engine is cool, loosen the filler cap. Then, allow the pressure out of the cooling system. Remove the filler cap.