LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mazda >> 2000 >> B2500 SX, Automatic >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Controls Trouble Shooting (5 Of 5) >> Engine Cooling Symptom Chart >> Engine Cooling >> Pinpoint Test 2: The Engine Overheats
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Pinpoint Test 2: The Engine Overheats

PINPOINT TEST 2 - ENGINE OVERHEATS

PINPOINT TEST 2 THE ENGINE OVERHEATS
STEP INSPECTION ACTION
1 CHECK THE ENGINE COOLANT LEVEL
NOTE: If the engine is hot, allow the engine to cool before proceeding.
  • Key OFF.
    WARNING: Never remove the radiator cap under any conditions while the engine is operating. Failure to follow these instructions could result in personal injury and/or damage to the cooling system or engine. To avoid having scalding hot coolant or steam blow out of the radiator, use extreme care when removing the radiator cap from a hot radiator. Wait until the engine has cooled, then wrap a thick cloth around the radiator cap and turn it slowly to the first stop. Step back while the pressure is released from the cooling system. When you are certain all the pressure has been released, press down on the radiator cap (with a cloth), turn and remove.
  • Check the engine coolant level at the coolant recovery reservoir.
  • Is the engine coolant OK? 
 Yes Go to step 2.
No Refill the engine coolant at the coolant recovery reservoir.
See PINPOINT TEST 1: LOSS OF COOLANT .
2 CHECK THE COOLANT CONDITION
  • Check the coolant for contaminants such as rust, corrosion, or discoloration.
  • Is the coolant condition OK? 
 Yes Go to step 3.
No Flush the engine cooling system.
Test the system for normal operation.
3 CHECK FOR AN AIRFLOW OBSTRUCTION
  • Inspect the A/C condenser core and radiator for obstructions such as leaves or dirt.
  • Is there an obstruction? 
 Yes Remove the obstruction. Clean the A/C condenser core and radiator.
See REMOVAL & INSTALLATION in A/C-HEATER SYSTEMS article in Engine . Test the system for normal operation
No Go to step 4.
4 CHECK THE HEATER CORE OPERATION
  • Install the radiator cap.
  • Start the engine.
  • As the engine starts to heat up, feel the inlet and outlet heater hoses. They should feel approximately the same after three or four minutes.
  • Is the outlet heater hose approximately the same temperature as the inlet heater hose? 
 Yes Go to step 5.
No Turn the engine off. Repair or replace heater core.
See HEATER CORE in HEATER SYSTEMS article . Test the system for normal operation
5 CHECK THE THERMOSTAT OPERATION
  • Start the engine and allow the engine to run for ten minutes.
  • Feel the inlet and outlet heater hoses and the underside of the upper radiator hose.
  • Are the upper radiator hose and the heater hoses cold? 
 Yes Replace the thermostat.
Test the system for normal operation.
No Go to step 6.
6 CHECK THE COOLING FAN OPERATION
  • Key OFF.
  • Check cooling fan.
  • Is the cooling fan operation OK? 
 Yes See ENGINE SYMPTOM CHART  for diagnosis and testing of the engine
No Replace the fan component determined to be faulty. Test the system for normal operation.
scientia non olet · About LEMON Manuals