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When you realize that temperature inside your engine routinely exceed 400 degrees Farenheit, it’s obvious that cooling system maintenance is a must in order to avoid serious and costly engine damage. Most cars overheat because their owners do not take the time to do the specific periodic maintenance the cooling system needs. The procedures following will show you how easy it is to keep your car’s cooling system in top condition.
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RELIEVING RADIATOR PRESSURE
THere are three methods of relieving radiator pressure, depending on the type of cap used. Never attempt to remove any type of cap while the engine is operating. Doing so could damage the cooling system and engine and result in serious personal injury from hot coolant or steam being blown out. Turn off the engine and wait until it is completely cool.
1. If the cap has a pushbutton or lever, push the button or lift the lever to deperssureize the system. When the sound of air escaping can no longer be heard it is safe to remove the cap.
2. If the cap has no visible pressure realease, wrap a thick cloth around it and turn it slowly to the first stop. Step back while the pressure is released from the cooling system. When you are sure all the pressure has been released, press down on the cap with the cloth and turn completely counterclockwise to remove it.
3. If the cap is a swivel type, relieve pressure by turning the top. The top twists while the valve assembly beneath it remains stationary. When pressure is relieved press down on the cap to remove it.
Replacing Hoses
Carefully check all hoses at least once a year. Replace hoses when they are worn, cracked, or even partially split. Also, change any hose that feels mushy or brittle when squeezed firmly. To replace a hose, proceed as follows:
1. Drain the cooling system by removing the radiator cap (as previously explained) and loosening the petcock or removing the lower radiator hose.
2. Loosen the clamps and slide them out of the way.
3. If possible, twist and pull the hose. If it is struck, cut a 4″ to 5″ slit lengthwise from the end and use a screwdriver to pry it off.
4. Clean off the metal connection with a wire brush and coat the surface with sealing compound.
5. Slip a new clamp on each end of the hose.
6. Position the hose on the fittings. Remember that the lower radiator hose must be the wire-reinforced type.
7. Slide the clamps into position about 1″ from the end of the hose. Tighten securely.
8. Refill the cooling system and replace the radiator cap.
9. Run the engine and check for leaks.
Coolant Checks
A hydrometeris used to determine the coolant’s freezing point. If the freezing point is not adequate, drain off some solution and replace it with pure, undiluted antifreeze. If you have a 10 quart capacity system and the reading is +10 degrees Farenheit, drain 3qts, and add 3qts. of pure antifreeze, if the hydrometer reads 0 degrees Farenheit remove & add 2 1/2 qts. Of at -10 Degrees, remove & add 2. THe following is in the smae format without all the words. 12: 4,3,2;14:5,3 1/2, 2 1/2; 16: 5 1/2, 4, 3; 18: 6, 4 1/2, 3; 20: 7,5,3 1/2. The Freezing point should be at -34 degrees Farenheit, which will provide more than adequate protection in cold climates. Cooling system capacity can be found in your owner’s manual.
1. For the best results, operate the engine with the radiator cap loose until the engine reaches normal operating temperature; then remove the cap.
2. Measure the coolant temperature by drawing a sample into the tubes; then return the sample to the radiator. Reapeat serveral times until the reading is stable.
3. Holding the Hydrometer in a straight, vertival position, squeeze the bulb and pull enough coolant into the glass tibes to raise the hydrometer float. Make sire that the float does not touch sides of the larger tube.
4. Note the top letter touched by the coolant on the float scale; then return this sample to the radiator.
5. Refer to the temperature chart above the thermometer. Find the letter noted in the previous step, along with the thermometer reading taken in Step 2. THe number found at this location is the degree of freezing protection provided.
6. After adding the coolant, let the engine run for five minutes to allow the coolant to mix before rechecking the freezing point.
Pressure Check
Test the cooling system for leakage with a pressure tester. Perform this test before draining the coolant, or after replacing any hoses to make sure the system is holding pressure.
1. Loosen the radiator cap and run the engine until it reaches operating temperature. Be especially careful if you car has electric cooling fans; they turn on between 200 F & 220 F, thus causing a boil-overif the cap is off.
2. Turn off the engine, slowly remove the cap.
3. Install the special pressure cap over the radiator filler neck, making sure the cap has seated fully and is tight.
4. With the hand pump, pressurize the system to the ampunt specified by the manufacturer or the amount specified by the pressure cap. Usually a system that holds 15 PSI is pressure-tight.
5. If the reading on the pump remains stable, with little or no pressure loss, the system has no excessive leakage. If the gague indicates a sharp or gradual loss, a leak exists.
6. To locate a leak, keep the pressure in the system up to specification using the hand pump. Check carefully for external coolant leakage.
7. Tighten, repair, or replace leaking parts until the gague holds the specified pressure.
8. If no external leak is found, the leak may originate fro inside the engine. Have the car checked further by a mechanic.
The pressure tester can also be used to check the pressure rating and operation of the radiator cap as follows:
1. Attach the special pressure cap to the correct adapter. if the wrong adapter is used, the test results will not be accurate.
2. Connect the special cap assembly, attached to the tester’s hose, to the adapter. Connect the other end to the adapter to the radiator cap.
3. Operate the hand pump until the gague reads the same as the caps rating.
4. A good cap will hold pressure at or slightly below the cap’s rating for at least 30 seconds; then the pressure might decrease slowly.
5. If the pressure drops too quickly, or if no pressure can be built up, the blowoff valve in the cap is defective. Replace the cap.
6. If the gague reading does no drop off at all, continue to apply pressure until the cap vents. If the cap does not vent, or vents at a pressure more than 1 PSI above it’s rating, replace the cap.
Most carmakers reccomend flushing the cooling system every 2 years or 24,000 miles, but doing it once a year is best. This is because the antirust compound and other additives in antifreeze lose most of their effectiveness within a year. The safest and most practical way to flush the system is to use a flushing kit. This eliminates the need for opening the drain plugs of a hot engine and possibly getting burned. This kit takes about 5 minutes to install, it remains in place for future use. To install a flushing kit:
1. Release the pressure at the radiator cap.
2. Locate the heater hose that runs from the firewall to the engine block. There are two such hoses: one to the water pump, the other to the engine block.
3. After making sure you have the right hose, cut it near the firewall using a sharp utility knife.
4. Slide a hose clamp on the end of each cut pieces. Make sure it fits snugly.
5. Insert the T-fitting, provided in the kit, between the two cut pieces. Make sure it fits snugly.
6. Slide the hose clamps into position, the tighten them.
7. Remove the raidator cap and insert the splash pipe into the neck.
8. Turn on the dashboard heater control so the the heater is flushed clean also.
9. Screw a garden hose onto the T-fitting.
10. Turn on the water full blast and let it run until the water coming out of the splash pipe in clear.
11. Turn off the water and disconnect the hose from the T-fitting. Do not screw on the cap yet.
12. Remove the splash pipe from the raidator and pour the correct amount of antifreezer into the system; this amount should equal half the system’s capacity (listed in the owner’s manual). The anti-freeze displaces half the water, which flows out of the T-fitting reulting in a 50/50 mixture.
13. Screw on the car on the T-fitting.
14. Start the engine, let it run, then turn it off after it reaches normal operating temperature.
15. Check the coolant level; it should be within 1″ of the neck. If more coolant is needed, add pure antifreeze; then replace the raidator cap.
16. Be sure to ad a 50/50 Mixture of antifreeze and water to the expansion tank.
Servicing The Thermostat
The thermostat controls the flow of coolant between the engine block and the radiator. When the engine is cold, the thermostat prevents flow of coolant to the radiator, thus permitting it to heat up more rapidly. As the engine warms up, it opens, allowing the coolant to flow to the radiator. The thermostst is usually located on the engine block at the top front of the engine.
To make an in-system check of the operation of the thermostat, proceed as follows:
1. With the engine is cold, remove the radiator cap. If the coolant level is low, add water to bring it up to a specified level.
2. Insert an accurate thermometer into the radiator filler neck. Again, watch for a boil-over if the car has electric cooling fans.
3. Start the engine and observe the thermometer while the engine is warming up.
4. Watch the coolant that is visible in the neck. As the thermostat opens, steam will rise from the coolant and begin to swirl around.
5. If the thermometer’s temperature reading remained nearly the same as the engine warmed up, then rose rapidly to the rating of the thermostat as it opened, and finally remained stationary at this temperature, the thermostat is operating properly.
6. If the temperature on the thermometer was below or above the rating of the thermostat as it opened, the thermostat must be replaced.
7. If the temperature rose steadily as the engine warmed up, then remained stationary somewhere bewteen 120 F & 150 F, the thermostat is either stuck wide open or missing from the system. In either case, replace the thermostat.
To replace the thermostat:
1. Remove the radiator cap in the matter described earlier, then loosen the petcock.
2. Drain at least one quart of coolant from the system. This lowers the coolant level in the engine block below the thermostat.
3. Tighten the petcock until it is snug.
4. Remove the thermostat housing bolts, then remove the thermostat housing. If it sticks, put a wood block against the housing and tap gently with a hammer until it comes loose.
5. Remove the thermostat and place a clean rag in the opening the dirt out.
6. Scrape the old gasket and sealer off the engine block and thermostat housing. Remove the rag from the opening.
7. Make sure the new thermostat is rated at the temperature rated by the car manufacturer.
8. Seat the new thermostat on the engine block. Make sure the spring side of the thermostat is pointing down into the engine.
9. Coat both sides of the new gasket with gasket sealing compound for a leakproof fit. Carefully place the gasket over the thermostat and the mounting surface of the engine block.
10. Place the thermostat housing on the gasket.
11. Install the two bolts and tighten. Do not overtighten; this can lead to damage of the housing.
12. Clamp the upper radiator hose on the thermostat housing. The calmp should be tightened about 1″ from the end of the hose.
13. Refill the system with a 50/50 mixture of water and antifreeze; reinstall the radiator cap.
14. Run the engine for 15 or 20 minutes; then check for leaks.
15. Turn off the engine and allow it to cool. Remove the radiator cap as described; recheck the coolant level; then reinstall the cap.
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