Malfunctions & Remedies


Overheating due to coolant flow:
Component Maintenance Malfunction Causes Remedies
Radiator Core Use recommended coolant. Bi-annual internal & external inspection. Poor coolant flow, radiator overheats. Clogged tubes or air passage (wrong rad for application). Boil out, rod out, recore, or replace.
Electric Fans Proper cycling, obstruction free. Defective motor or sensors. Normal wear or fuse. Repair or replace component.
Engine Block Check system visually for rust, drain and clean system per manufacture requirements. Overheats engine Rust buildup in water jacket reduces heat transfer at engine walls. Maintain proper coolant.
Fan Belt Check tension regularly. Inspect cracks for burning. Belt slips or breaks. Wrong tension, normal wear. Tighten or replace.
Fan or blades check for loose or bent blades. Radiator overheats, especially at idle speeds. Bent of loose blades, defective fan clutch or electric motor, or defective thermal switch components. Replace.
Hose Inspect periodically for watter logged hose, or soft spots. Hose leaks or collapses under pressure. Hose rotten internally or split. Replace hose.
Pressure cap Inspect seals. Loss of pressure and coolant overheats. Defective cap. Replace.
Water pump Check belt for tension, and pully shaft play. Leaky pump, noisy pump, broken impeller. Belt tension, normal wear. Replace pump.
Overheating due to airflow:
Component Maintenance Malfunction Causes Remedies.
AC Condensor Check for bent fins and clogged air passages. Restricted airflow. bent fins or clogged air passages. Blow clean with air pressure from engine side.
Bug Screen Remove and clean periodically Restricted airflow. Clogged surface. Wash with water.
Fan Belt Check tension regularlly, and inspect cracks or burning. Belt slips or breaks. Wrong tension, normal wear. Tighten or replace.
Fan or Blades Check for loose or bent blades. Check temperature actuating elements. Radiator overheats (especially at idle speeds). Bent or loose blades. Defective fan clutch, electric motor, or thermal switch component. Replace.
Fan Clutch Check temperature-actuating elements for proper operation and calibration. Insufficient air drawn through radiator. Normal wear, sticky control piston, cracked bimetallic strip. Replace part or complete assembly.
Radiator Fins Straighten fins, keep open. Restricted airflow. Bent fins, clogged fins. Straighten fins, flush from engine side.
Radiator Surface Check for bent fins, and clogged air passages. Restricted airflow. Bent fins or clogged air passages. Flush with low pressure hose from engine side to front. Straighten fins.
Shroud Check for fan clearance or air leaks at radiator attachement and cracks in the shroud. Engine over heats. Poor distribution of airflow. Adjust or replace.
Overheating due to engine:
Component Maintenance Malfunction Causes Remedies
Timing Tune regularly. Overheating. Bad valve and ignition timing. Tune engine to specifcations.
Overheating due to brakes:
Component Maintenance Malfunction Causes Remedies
Brake Lining Adjust and inspect brakes regularly. Overheating. Binding breaks. Adjust or reline brakes.
Overheating due to exhaust system:
Component Maintenance Malfunction Causes Remedies
Muffler, Catalytic Converters and Pipe. Check periodically. Increased back pressure resulting in overheating. Obstruction or defect in muffler, catalytic converter and/or pipes. Replace muffler, catalytic converter, pipes, or all.
Overheating due to air conditioning:
Component Maintenance Malfunction Causes Remedies
Condensor Keep condensor free of obstruction for free airflow. Restricted airflow, overheating. Clogged condensor, faulty compressor. Clean condensor (exterior). Replace fan and shroud.


Component Maintenance Malfunction Causes Remedies
Temperature gauge and sensing unit. Check temperature of coolant with thermometer against actual reading. Clean engine sensing unit of any coating or buildup. Check for good ground. Consistent temperature gauge readings above the normal range (or below). defective temperature gauge or sending unit. Replace temperature gauge or sensing unit or both. Check thermostat.
Thermostat Inspect annually and replace as necessary. Thermostat sticks in open position. Defective thermostat. Replace thermostat. It cannot be repaired.

Loss of Coolant

Loss of coolant due to external leakage:
Component Maintenance Malfunction Causes Remedies
Freeze plugs Inspect with each lubrication. Leaking coolant. Improper installation, contaminated coolant, freeze up. Replace plug(s) with correct sealing compound.
Gaskets, drain cocks Inspect annually at water pump, thermostat housing, cylinder head. Inspect drain cock at radiator. Leaking gaskets, blown gaskets, leaky drain cock. Faulty installation, excessive pressure, wear, fatigued plastic. Tighten or replace.
Hoses and clamps Inspect monthly for loose clamps, rotted or waterlogged hose. Leaking or split hose. May rot internally. Clamp my be broken. Faulty hose, loose clamps, normal wear. Replace hose, tighten or replace clamp.
Radiator Use manufacturer’s recommended coolant. Check coolant level weekly. Investigate evidence of low level immediately. External biannual cleaning, replace coolant as per manufacturer’s specifications. Poor coolant flow, leaks, plugged core, overheating, cracked tanks. Vibration, sediment build up, or tubes clogged air passages, over pressurized. Boil out, repair leaks, recore, replace or recrimp.
Water pump Check belt tension and pulley play. Leak at shaft or backing plate, corroded or broken impeller. Excessive bearing wear. Belt tension, contaminated coolant. Replace.
Loss of coolant due to internal leakage:
Component Maintenance Malfunction Causes Remedies
Head Visual inspection for leaks or cracks. Torque-tighten hold down bolts periodically. Overheating, frozen coolant, faulty head. Machine or replace head, or replace gasket.
Head gasket Inspect for leaks or seepage. Overheating possible water in oil or oil in coolant. Faulty gasket, improper installation, warped head or block. Tighten or replace. Machine head.
Loss of coolant due to overflow:
Component Maintenance Malfunction Causes Remedies
Coolant Fill radiator or correct level. Loss of coolant. Overfilling radiator or overflow jug. Fill radiator and overflow jug to manufacturer’s specifications.
Foaming Regular check of hoses, water pump, head. Air being sucked into coolant (aeration) or No Anti-foaming agent. Leaky head, cracked head or block. Improper antifreeze. Check for leak; replace faulty component.
Pressure cap Check cap with pressure tester. inspect rubber seals for cracking. Cap does not hold prescribed pressure. Pressure is not relieved at prescribed pressure. Pressure or vacuum valve sticks open. Poor sealing between filler neck and cap. Check valve seat, gasket, and cap. Replace if faulty.
Surging Inspect pressure cap, thermostat regularly. Loss of coolant when engine is stopped. Faulty pressure cap, thermostat, clogged radiator. Check or replace pressure cap, thermostat, boil out radiator.
Thermostat Inspect annually and check. Thermostat opens at too high temperature. Wrong degree thermostat. Replace with correct temperature thermostat.