Section 03-03: Engine Cooling
1993 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Coolant Recovery System

In the event no coolant is observed in the reservoir, or when a coolant level change does not occur, check the system as follows:

  1. With the engine cold, remove the radiator pressure cap, and inspect the filler neck sealing gasket for foreign material between the gasket and cap diaphragm. Refer to Radiator Pressure Cap Cleaning and Inspection. Rinse cap in clean water.

    The radiator pressure cap used on this system is unique, replace only with the proper cap.

  1. Remove the radiator overflow-to-reservoir hose at the radiator filler neck connection. Remove coolant recovery reservoir and flush with clean water.
  1. Inspect the reservoir hose for obstruction, cracks or cuts. Replace if necessary.
  1. Inspect filler neck nipple to neck flared soldered joint for possible separation. Service if necessary.
  1. Install coolant recovery reservoir and connect overflow hose at the radiator filler neck connection.
  1. Replenish the coolant with 50/50 mixture in the radiator and add coolant to plastic reservoir to the cold mark.
  1. Install the radiator pressure cap.

    Refer to the diagnosis chart. Refer to the applicable Section for testing and service.

    Use a cooling system analyzer to assist in diagnosing the cooling system. Follow the manufacturer's instructions for connections and testing. The most frequent cooling system conditions concern leakage and overheating. Either of these conditions can make the vehicle inoperable.

    Most vehicles use an ethylene glycol base antifreeze solution to which the manufacturers have added a dye color. The dye color makes the antifreeze solution an excellent leak detector.

ConditionPossible SourceAction
  • Loss of Coolant
  • Pressure cap and gasket.
  • Inspect and clean gasket and test. Replace only if cap will not hold pressure test specification.
 
  • Leakage.
  • Pressure test system.
 
  • External leakage.
  • Inspect hose, hose connection, radiator, edges of cooling system gaskets, core plugs and drain plugs, transmission oil cooler lines, water pump, heater system components. Service or replace as required.
 
  • Reservoir filler leak.
  • Inspect reservoir filler neck sealing surface for damage or foreign material.
 
  • Internal leakage.
  • Check engine oil and transmission oil dipsticks for signs of coolant. Check coolant for signs of transmission oil.
  • Check torque of head bolts, tighten if necessary.
  • Disassemble engine as necessary—check for cracked intake manifold, blown head gaskets, leak at water crossover intake manifold gasket, warped head or block gasket surfaces, cracked cylinder head or engine block.
  • Engine Overheats
  • Low coolant level.
  • Fill as required. Check for coolant loss.
 
  • Excessive rust in coolant.
  • Flush system, refill with new coolant.
 
  • Loose fan belt.
  • Check automatic belt tensioner and/or belt.
  • Test. Replace if necessary.
 
  • Fan control.
  • Adjust.
 
  • Pressure cap.
  • Test. Replace if necessary.
 
  • Radiator or A/C condenser obstruction.
  • Remove bugs, leaves, etc.
 
  • Closed thermostat.
  • Test, replace if necessary.
 
  • Fan drive clutch. (5.0L Only)
  • Test, replace if necessary.
 
  • Ignition.
  • Check timing and advance. Adjust as required.
 
  • Temp gauge or cold light. (False reading).
  • Check electrical circuits and service as required. Refer to Section 13-01.
 
  • Engine.
  • Check water pump, block for blockage.
 
  • Exhaust system.
  • Check for restrictions.
  • Engine Fails to Reach Normal Operating Temperature
  • Open thermostat.
  • Test, replace if necessary.
 
  • Temperature gauge and/or sending unit (False reading).
  • Check electrical circuits and service as required. Refer to Section 13-01.
 
  • Low coolant level.
  • Fill cooling system, as required.
  • Block Heater Fails to Warm Engine Coolant
  • Block heater power cable.
  • Test, replace if necessary.
 
  • Block heater.
  • Test, replace if necessary.