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GENERAL INFORMATION AND MAINTENANCE
Fig. 155 Check the condition of the radiator cap gasket and seal
Fig. 156 I sped coolant for contamination
LEVEL CHECK 1. Check the level on the see-through expansion tank.
CAUTION The radiator coolant is under pressure when hot. To avoid the i anger of physical harm, coolant level should be checked or replenish id only when the engine is cold. To remove the radiator cap when the engine is hot, first cover the cap with a thick rag, or wear a hef vy glove for protection. Press down on the cap slightly and slowly turn it counterclockwise until it reaches the first stop. Allow all the pr ssure to vent (indicated when the hissing sound stops). When the prt ssure is released, press down on the cap and continue to rotate it co) nterclockwise. Some radiator caps have a lever for venting the pre sure but you should still exercise extreme caution when removing tie cap. 2. Check the level and, if necessary, add coolant through the expans on tank to the proper level. Use a 50/50 mix of ethylene glycol anti-freeze and w ter. Alcohol or methanol base coolants are not recommended. Anti-freeze scj utions should be used, even in summer, to prevent rust and to take advantage t the solution's higher boiling point compared to plain water. This is imperathp on air conditioned trucks; the heater core can freeze if it isn't protected. Cooian should be added through the coolant recovery tank, not the radiator fille neck.
WARNING Never add large quantities of cold coolant to a hot engine! A cracked engine block may result! Each year the cooling system should be serviced as follows • Wash the radiator cap and filler neck with clean water. • Check the coolant for proper level and freeze protection. • Have the system pressure tested 15 psi. (103 kPa), If a replacemer) cap is installed, be sure that it conforms to the original specifications. • Tighten the hose clamps and inspect all hoses. Replace hoses that|are swollen, cracked or otherwise deteriorated. • Clean the frontal area of the radiator core and the air conditioning Condenser, if so equipped. DRAINING & FLUSHING
Fig. 157 Master cylinder fluid level
any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant Into a scalable container. Coolant should be reused unless it is contaminated or several years old. 1. Drain the existing anti-freeze and coolant. Open the radiator and engine drain petcocks (located near the bottom of the radiator and engine block, respectively), or disconnect the bottom radiator hose at the radiator outlet. 2. Close the petcock or reconnect the lower hose and fill the system with water—hot water if the system has just been run. 3. Add a can of quality radiator flush to the radiator or recovery tank, following any special instructions on the can. 4. Idle the engine as long as specified on the can of flush, or until the upper radiator hose gets hot. 5. Drain the system again. There should be quite a bit of scale and rust in the drained water. 6. Repeat this process until the drained water is mostly clear. 7. Close all petcocks and connect all hoses. 8. Flush the coolant recovery reservoir with water and leave empty. 9. Determine the capacity of your truck's cooling system (see Capacities specifications in this guide). Add a 50/50 mix of ethylene glycol anti-freeze and water to provide the desired protection. 10. Run the engine to operating temperature, then stop the engine and check for leaks. Check the coolant level and top up if necessary. 11. Check the protection level of your anti-freeze mix with an anti-freeze tester (a small, inexpensive syringe type device available at any auto parts store). The tester has five or six small colored balls inside, each of which signify a certain temperature rating. Insert the tester in the recovery tank and suck just enough coolant into the syringe to float as many individual balls as you can (without sucking in too much coolant and floating all the balls at once). A table supplied with the tester will explain how many floating balls equal protection down to a certain temperature (three floating balls might mean the coolant will protect your engine down to +5F (-15C), for example.
Brake Master Cylinder FLUID RECOMMENDATIONS I See Figure 157 Use only Heavy Duty Brake fluid meeting or exceeding DOT 3 standards.
The cooling system in you truck accumulates some internal rust and coirosion in its normal operation. A simple method of keeping the system clean is kn jwn as flushing the system. It is performed by circulating a can of radiator flush thiough the system, and then draining and refilling the system with the normal cool.int. Radiator flush is marketed by several different manufacturers, and is availal: le in cans at auto departments, parts stores, and many hardware stores. This operation should be performed every 30,000 miles (48,000 kmjor once a year.
CAUTION When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol anti-freeze, and are quite likely to drink
LEVEL CHECK > See Figures 158 and 159 Chevrolet and GMC trucks are equipped with a dual braking system, allowing a vehicle to be brought to a safe stop in the event of failure in either front or rear brakes. The dual master cylinder has 2 entirely separate reservoirs, one connected to the front brakes and the other connected to the rear brakes. In the event of failure in either portion, the remaining part is not affected. Fluid level in the master cylinder should be checked on a regular basis. The master cylinder is mounted to the left side of the firewall.