Section 03-03: Engine Cooling
1994 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Pinpoint Tests

  

PINPOINT TEST A: LOSS OF COOLANT

 

A1 CHECK COOLANT LEVEL

NOTE: If engine is hot, allow engine to cool down before proceeding.

Yes
GO to A2.

No
REFILL as outlined. GO to A2.

 

A2 CHECK FOR VISIBLE LEAKAGE

Yes
SERVICE as outlined. RETEST system.

No
GO to A3.

 

A3 CHECK RADIATOR CAP

  • Using Rotunda Radiator/Heater Core Pressure Tester 021-00012 or equivalent, test radiator cap as outlined in Component Testing.
  • Did radiator cap test OK?
Yes
GO to A4.

No
REPLACE damaged radiator cap . RETEST system.

 

A4 CHECK COOLANT FOR INTERNAL LEAKAGE

  • Visually inspect coolant in radiator and radiator coolant recovery reservoir for signs of transmission or engine oil.
  • Is oil evident in coolant?
Yes
If engine oil is evident, GO to Section 03-00. If transmission oil is evident GO to Service Procedures in this Section and Section 07-01.

No
GO to A5.

 

A5 CHECK ENGINE AND TRANSMISSION FOR COOLANT

  • Remove oil level indicator from engine and transmission.
  • Carefully inspect oil level indicator for evidence of coolant.
  • Is coolant evident?
Yes
If coolant is in engine GO to Section 03-00. If coolant is in transmission GO to Section 07-01 and Service Procedures in this Section.

No
GO to A6.

 

A6 PRESSURE TEST COOLING SYSTEM

  • Using Rotunda Radiator/Heater Core Pressure Tester 021-00012 or equivalent, pressurize cooling system as outlined in Service Procedures in this Section.
  • Check for any signs of visible leakage.

    NOTE: Check inside vehicle for possible heater core leakage.

  • Is there leakage?
Yes
SERVICE as outlined in Service Procedures in this Section. RETEST system.

No
Cooling system is operational at this time. RETEST system.

  

PINPOINT TEST B: ENGINE OVERHEATS

 

B1 CHECK COOLANT LEVEL

NOTE: If engine is hot, allow engine to cool down before proceeding.

  • Remove radiator cap and check coolant level at radiator and radiator coolant recovery reservoir .
  • Is coolant level OK?
Yes
GO to B2.

No
REFILL as outlined. GO to Test A.

 

B2 CHECK COOLANT CONDITION

  • Check coolant for contaminants such as rust or corrosion. Also check for fluid discoloration.
  • Is coolant condition OK?
Yes
GO to B3.

No
FLUSH system as outlined in Service Procedures in this Section. RETEST system.

 

B3 CHECK FOR AIR FLOW OBSTRUCTION

  • Visually inspect A/C condenser core and radiator for obstructions such as leaves or bugs.
  • Is there any obstruction?
Yes
REMOVE obstruction and CLEAN A/C condenser core and radiator as outlined. RETEST system.

No
GO to B4.

 

B4 CHECK HEATER CORE OPERATION

  • Install radiator cap .
  • As engine starts to warm up, feel the inlet and outlet heater water hoses . They should feel the same after three or four minutes.
  • Is outlet heater water hose the same temperature as the inlet heater water hose?
Yes
GO to B5.

No
TURN engine OFF before it overheats. SERVICE heater core as outlined in Service Procedures in this Section. RETEST system.

 

B5 CHECK WATER THERMOSTAT OPERATION

  • Allow engine to run for 10 minutes.
  • Feel the inlet and outlet heater water hoses and the underside of the upper radiator hose .
  • Are the upper radiator hose and heater water hoses cold?
Yes
REPLACE water thermostat as outlined in Service Procedures in this Section. RETEST system.

No
Leave engine RUNNING. GO to B6.

 

B6 CHECK COOLING FAN

  • Check temperature gauge at instrument cluster . Allow engine to RUN until high side of normal range is attained.
  • Check for cooling fan operation.
  • Did cooling fan operate OK?
Yes
GO to Section 03-00 for engine service procedure.

No
GO to Section 12-00 for proper service procedure.

  

PINPOINT TEST C: ENGINE DOES NOT REACH NORMAL OPERATING TEMPERATURE

 

C1 CHECK ENGINE TEMPERATURE

  • Start engine and allow to RUN for 15 minutes.
  • Feel inlet and outlet heater water hoses and underside of upper radiator hose .
  • Are upper radiator hose and heater water hoses cold?
Yes
REPLACE water thermostat as outlined in Service Procedures in this Section. RETEST system.

No
GO to Section 13-01 for proper temperature gauge testing procedure.

  

PINPOINT TEST D: ENGINE BLOCK HEATER DOES NOT OPERATE PROPERLY

 

D1 CHECK POWER CABLE

  • Check continuity of Circuits 1, 2 and 3 in power cable using Rotunda Digital Volt Ohmmeter 014-00407 or equivalent.
  • Is there continuity in Circuits 1, 2 and 3?




Yes
REPLACE block heater. RETEST system.

No
REPLACE power cable. RETEST system.