Chevrolet Light Duty Truck 1973 Service Manual page 422

6 K - 1 2 E N G IN E C O O L IN G
Once level becomes stabilized, it will not change
appreciable during operation.
2. Check for crack in block. Pull engine oil dip-stick to
check for water in crankcase.
3. Remove rocker arm covers and check for cracked
cylinder head.
4. Remove cylinder heads and check gaskets. While
heads are off, check for cracks in heads or block.
Overheating
1. Check to see that the radiator cap seats in radiator
filler neck and releases at specified pressure (15 lb.).
2. Check coolant level.
3. Check temperature sending unit and/or gauge.
4. Check engine thermostat.
5. Check fan belt for excessive looseness.
6. Check for punctures in radiator, ruptured or
disconnected hoses, loose pressure cap or use of low
boiling point antifreeze. These conditions prevent
cooling system from maintaining proper pressure.
7. Clean debris from radiator and/or condenser.
8. Check engine operation to make sure tune-up is not
needed. Improper timing may cause overheating.
9. Check for driving conditions which may cause
overheating. Prolonged idling, start and stop
driving in long lines of traffic on hot days, climbing
steep grades on hot days, etc. will occasionally cause
coolant to boil.
10. Clean cooling system.
11. Remove cylinder heads and check water passages in
heads and block for obstructions.
LIGHT DUTY TRUCK SERVICE MANUAL