Initial Inspection and Diagnostic Overview
COOLING SYSTEM INSPECTION 4.0LWarning:
^ To avoid personal injury, do not unscrew the coolant relief cap while the engine is operating or hot. The coolant system is under ; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions can result in personal injury.
Caution:
^ Check the coolant level, engine oil and transmission fluid. Top off the coolant if needed. If there is engine coolant in the engine oil or transmission fluid, the cause must be corrected and oil/fluid changed or major component damage can occur.
Caution:
^ Vehicle cooling systems are filled with Mazda Premium Gold Engine Coolant VC-7-A (in Oregon VC-7-B) (yellow color). Do not mix coolant types.
Note:
^ Check the coolant in the coolant recovery reservoir and radiator, if vehicle has not been allowed to reach normal operating temperature. This will make sure sufficient coolant exchange has occurred.
1. Inspect to determine if any of the following mechanical or electrical concerns apply.
Visual Inspection Chart
2. If the inspection reveals an obvious concern that can be readily identified, repair it as necessary.
3. Allow the engine to cool and remove the radiator cap.
4. Inspect the coolant in both radiator and the coolant recovery reservoir for coolant color:
^ Clear light green, blue or pale yellow color indicates higher water content than required.
^ Dark brown indicates possible use of unauthorized stop leak.
^ A light or reddish brown color indicates rust in the cooling system. Flush the system and refill with the correct mixture of water and engine coolant.
^ An iridescent sheen on top of the coolant indicates a trace of oil is entering the cooling system.
^ A milky brown color indicates that oil is entering the cooling system.
^ A reddish milky appearance indicates transmission fluid is entering the system.
Caution:
^ If there is coolant in the engine oil, the cause must be corrected and the oil changed or engine damage may occur.
5. The causes of the leak might be:
^ A blown head gasket.
^ A cracked or warped cylinder head.
^ A crack in the engine oil gallery and the cooling passage ways.
6. The causes of other leaks might be:
^ A leaky radiator.
^ A leaky transmission fluid cooler.
7. Drain the fluids and repair or replace as required.
Add the proper mixture of water and engine coolant.
8. If the coolant appearance is OK, test the coolant range.
^ Maximum range is 60/40.
^ Minimum range is 45/55.
9. Coolant system conditions:
^ If the cooling system is low, top off only with a premixed solution.
^ If the coolant mixture is weak, add straight coolant until the readings are within acceptable levels.
^ If the coolant mixture is strong, remove some coolant and add water until the readings are within acceptable levels.