Engine Cooling System Test


Engine And Cooling System Heat Problems

The following conditions indicate that a heat problem exists.
Hot coolant is released through the pressure cap during the normal operation of the engine. Hot coolant can also be released when the engine is stopped.
Hot coolant is released from the coolant system but not through the pressure cap during normal operation of the engine. Hot coolant can also be released when the engine is stopped.
Coolant must be added frequently to the cooling system. The coolant is not released through the pressure cap or through an outside leak.
If any of the conditions exist, perform the following procedures:
Run the engine at medium idle, which is approximately 1200 rpm, for three minutes after the high idle shuts off. Running the engine at medium idle will allow the engine to cool before the engine is stopped.
Inspect the poly v-belt for wear or for damage. If necessary, replace the poly v-belt.
If the coolant does not flow through the radiator and through other components of the cooling system, perform the following procedures.
Clean the radiator and other components with hot water or steam at low pressure. Detergent in the water may also be used. Compressed air may be used to remove materials from the cooling system. Identify the cause of the restriction before you choose the method for cleaning.
Straighten any fins of the radiator if the fins are bent.
Check the high idle of the engine. The engine may overheat if the high idle rpm is set too high.

Remember that temperature and pressure work together. When a diagnosis is made of a cooling system problem, temperature and pressure must be checked. The cooling system pressure will have an effect on the cooling system temperature.

Cooling system pressure at specific altitudes and boiling points of water

The coolant level must be to the correct level in order to check the coolant system. The engine must be cold and the engine must not be running. After the engine is cool, loosen the pressure cap in order to relieve the pressure out of the cooling system. Then 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 pipe. If the cooling system is equipped with a sight glass, the coolant should be to the correct level in the sight glass.

Making the Correct Antifreeze Mixtures

Do not add pure antifreeze to the cooling system in order to adjust the concentration of antifreeze. The pure antifreeze increases the concentration of antifreeze in the cooling system. The increased concentration increases the concentration of dissolved solids and undissolved chemical inhibitors in the cooling system. The antifreeze mixture must consist of equal quantities of antifreeze and clean soft water. The corrosion inhibitor in the antifreeze will be diluted if a concentration of less than 50% of antifreeze is used. Concentrations of more than 50% of antifreeze may have the adverse effect on the performance of the coolant.

Checking the Filler Cap

One cause for a pressure loss in the cooling system can be a faulty seal on the radiator pressure cap.

Typical schematic of filler cap
(1) Sealing surface between the pressure cap and the radiator

To check for the amount of pressure that opens the filler cap, use the following procedure:
After the engine cools, carefully loosen the filler cap. Slowly release the pressure from the cooling system. Then, remove the filler cap.
Carefully inspect the filler cap. Look for any damage to the seals and to the sealing surface. Inspect the following components for any foreign substances:
• Filler cap
• Seal
• Surface for seal
Remove any deposits that are found on these items, and remove any material that is found on these items.
Install the pressure cap onto a suitable pressurizing Pump.
Observe the exact pressure that opens the filler cap.
Compare the pressure to the pressure rating that is found on the top of the filler cap. If the filler cap is damaged, replace the filler cap.

Testing The Radiator And Cooling System For Leaks

Use the following procedure to test the radiator and the cooling system for leaks.
When the engine has cooled, loosen the filler cap to the first stop. Allow the pressure to release from the cooling system. Then remove the filler cap.
Make sure that the coolant covers the top of the radiator core.
Put a suitable pressurizing Pump onto the radiator.
Use the pressurizing pump to increase the pressure to an amount of 20 kPa (3 psi) more than the operating pressure of the filler cap.
Check the radiator for leakage on the outside.
Check all connections and hoses of the cooling system for leaks.
The radiator and the cooling system do not have leakage if all of the following conditions exist:
• You do NOT observe any leakage after five minutes.
• The dial indicator remains constant beyond five minutes.
The inside of the cooling system has leakage only if the following conditions exist:
• The reading on the gauge goes down.
• You do NOT observe any outside leakage.
Make any repairs, as required.