Hummer H2. Manual - part 72

Fig. 1: Drive Axle Gear Tooth Patterns 

C:\DOCUME~1\JAYFOS~1\LOCALS~1\Temp\mric_tmp\~od18C.jpg (2104 x 1532) @ 564.48px

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION Gear Tooth Contact Patterns

  

GENERAL INFORMATION 

General Cooling System Service 

DESCRIPTION 

The liquid cooling system consists of a radiator, water pump, thermostat, electric or belt-driven cooling fan, 
pressure cap, heater, and various connecting hoses and cooling passages in the engine block and cylinder head.  

MAINTENANCE 

DRAINING 

Remove radiator cap and open heater control valve to maximum heat position. Open drain cocks or remove 
plugs in bottom of radiator and engine block. In-line engines usually have one plug or drain cock, while "V" 
type engines have 2, one in each bank of cylinders.  

FLUSHING 

Radiator 

Connect flushing gun to water outlet of radiator. Disconnect water inlet hose. To prevent flooding engine, use a 
hose connected to radiator inlet. Use air in short bursts to prevent damage to radiator. Continue flushing until 
water runs clear.  

Engine Block 

To flush engine, remove thermostat. Connect flushing gun to water outlet of radiator. Use air in short bursts to 
prevent damage to radiator. Continue flushing until water runs clear.  

REFILLING 

To prevent air from being trapped in engine block, engine should be running when refilling cooling system. 
After system is full, continue running engine until thermostat is open, then recheck fill level. Do not overfill 
system.  

TESTING 

THERMOSTAT 

1. Remove and inspect thermostat for corrosion and proper seating of valve. If okay, suspend thermostat and 

thermometer in a 50/50 mixture of coolant and water. See Fig. 1 . DO NOT allow thermostat or 

CAUTION: Some manufacturers use an aluminum and plastic radiator. Flushing 

solution must be compatible with aluminum. 

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION General Cooling System Service

  

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION General Cooling System Service

  

thermometer to touch bottom or container. Heat water until thermostat begins to open.  

2. Read temperature on thermometer. This is the initial opening temperature and should be within 

specification. Continue heating water until thermostat is fully open and note temperature. This is the fully 
open temperature. If either reading is not to specification, replace thermostat.  

Fig. 1: Testing Thermostat in Coolant/Water Solution 

PRESSURE TESTING 

A pressure tester is used to check both radiator cap and complete cooling system. Follow pressure tester 
manufacturer instructions and test components as follows:  

Radiator Cap 

Visually inspect radiator cap. If cap looks okay, connect pressure tester to cap. See Fig. 2 . Pressurize tester to 
full radiator cap specification. Replace cap if it fails to hold pressure. 

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION General Cooling System Service

  

Fig. 2: Pressure Testing Radiator Cap 

Cooling System 

1. Turn ignition off and allow engine to cool. Ensure radiator if filled to correct level. Remove cap and 

attach pressure tester to radiator. Pressurize tester to full radiator rating specification.  

2. If pressure drops, check for external leaks. If no leaks are found, start engine and allow to idle. If pressure 

builds up immediately, check cylinder head and block for cracks. If pressure does not build up 
immediately, go to next step. 

3. Using pressure tester, pump cooling system up to pressure specified on radiator cap. If pump gauge 

pointer vibrates, compression or combustion leak into cooling system is indicated. Isolate leak by 
shorting each spark plug wire to cylinder block. Gauge pointer vibration will stop or decrease when 
leaking cylinder is shorted.  

CAUTION: DO NOT allow excess pressure to build in cooling system or damage 

may result. 

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION General Cooling System Service