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Home >> Chevrolet >> 1986 >> Forward Control 6.2 J, Automatic, 475/M40 >> Repair and Diagnosis >> Engine Mechanical >> Engine Cooling Fan >> Cooling System Maintenance >> Testing >> Pressure Testing Cooling System

Pressure Testing Cooling System

  1. With engine stopped, wipe radiator filler neck seat clean. Fill radiator to correct level. Attach cooling system tester to radiator and pump until pressure is at upper level of radiator rating. If pressure drops, inspect for external leaks. If no external leaks are evident, start engine and run with tester attached.
    NOTE: Pressure may build up quickly. Release any pressure above limit of pressure cap specifications or cooling system damage may result.
  2. Extremely rapid build-up of pressure may indicate combustion leak into cooling system. Check for water at tailpipe. Water could indicate faulty head gasket, cracked block or cylinder head near exhaust ports. Remove oil dipstick and check for water droplets in oil. If water is evident, serious internal leak is indicated.
    Fig 1: Pressure Testing Cooling System
    G92121