GM Bonneville/Eighty Eight/LeSabre 1986-1999

Cooling System

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See Figure 1


CAUTION
Never remove the radiator cap under any conditions while the engine is hot! Failure to follow these instructions could result in damage to the cooling system, engine and/or personal injury. To avoid having scalding hot coolant or steam blow out of the radiator, use extreme care whenever you are removing the radiator cap. Wait until the engine has cooled, then wrap a thick cloth around radiator cap and turn it slowly to the first stop. Step back while the pressure is released from the cooling system. When you are sure the pressure has been released, press down on the radiator cap (still have the cloth in position), turn and remove the cap.

The engine is kept cool by a liquid circulating through the engine to a radiator. In the radiator, the liquid is cooled by air passing through the radiator tubes. The coolant is circulated by a rotating water pump driven by the engine crankshaft. The complete engine cooling system consists of a radiator, recovery system, cooling fan, thermostat, water pump and serpentine belt.



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Fig. Fig. 1: Cutaway view of a typical cooling system flow

FLUID RECOMMENDATIONS




WARNING
For 1996-99 vehicles, when adding coolant, it is important that you use DEX-COOL®, an orange colored, silicate-free coolant meeting GM specifications 6277M. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result.

The cooling system should be inspected, flushed and refilled with fresh coolant at least every 30,000 miles (48,000 km) or 24 months. If the coolant is left in the system too long, it loses its ability to prevent rust and corrosion.

When the coolant is being replaced, use a good quality antifreeze that is safe to be used with aluminum cooling system components. The ratio of antifreeze to water should always be a 50/50 mixture. This ratio will ensure the proper balance of cooling ability, corrosion protection and antifreeze protection. At this ratio, the antifreeze protection should be good to -2°F (-37°C). If greater antifreeze protection is needed, the ratio should not exceed 70% antifreeze to 30% water.

LEVEL CHECK



See Figures 2 and 3

When checking the coolant level, the radiator cap need not be removed. Simply check the coolant level in the recovery bottle or surge tank.



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Fig. Fig. 2: On many vehicles, the coolant recovery reservoir is mounted on the fenderwell, near the battery

Check the coolant level in the recovery bottle or surge tank, usually mounted on the inner fender. With the engine cold, the coolant level should be at the FULL COLD or between the FULL HOT and ADD level. With the engine at normal operating temperature, the coolant level should be at the FULL HOT or HOT mark. Only add coolant to the recovery bottle or surge tank as necessary to bring the system up to a proper level.



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Fig. Fig. 3: Coolant level should be between the FULL HOT (A) and ADD (B) marks, depending upon the temperature


CAUTION
Should it be necessary to remove the radiator cap, make sure the system has had time to cool, thereby reducing the internal pressure.

On any vehicle that is not equipped with a coolant recovery bottle or surge tank, the level must be checked by removing the radiator cap. This should only be done when the cooling system has had time to sufficiently cool after the engine has been run. The coolant level should be within 2 in. (51mm) of the base of the radiator filler neck. If necessary, coolant can then be added directly to the radiator.

COOLING SYSTEM INSPECTION



Checking the Radiator Cap Seal

See Figure 4

While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat.

Worn caps should be replaced with a new one.



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Fig. Fig. 4: Be sure the rubber gasket on the radiator cap has a tight seal

Checking the Radiator For Debris

See Figure 5

Periodically clean any debris; leaves, paper, insects, etc. from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.

Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful, the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not move them again.



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Fig. Fig. 5: Periodically removal all debris from the radiator fins

DRAIN & REFILL



See Figures 6, 7, 8, 9 and 10


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze and are quite likely to drink 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 sealable container. Coolant should be reused until it is contaminated or several years old. To avoid injuries from scalding fluid and steam, DO NOT remove the radiator cap while the engine and radiator are still hot.

  1. Make sure the engine is cool and the vehicle is parked on a level surface, remove the radiator cap by performing the following:
    1. Slowly rotate the cap counterclockwise to the detent.
    2.  
    3. If any residual pressure is present, WAIT until the hissing stops.
    4.  
    5. After the hissing noise has ceased, press down on the cap and continue rotating it counterclockwise to remove it.
    6.  

  2.  
  3. Remove the recovery bottle or surge tank cap.
  4.  

You may want to attach a short piece of hose or tubing to the radiator drain tube to prevent the coolant from running everywhere during draining.

  1. Place a fluid catch pan under the radiator. Open the radiator drain valve, which is located at the bottom of the radiator tank, by turning it counterclockwise. It may be wise to coat the fitting with penetrating lubricant before you attempt to turn it. Also, it's a good idea to attach a hose to the drain tube to prevent a mess. Allow the coolant to completely drain from the radiator.
  2.  



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Fig. Fig. 6: Location of the drain valve (1) and drain hole (2)

  1. Remove the thermostat housing cap and thermostat, or open the air bleed vent(s), if applicable.
  2.  
  3. Remove the drain plug(s) from the engine block (located on the engine block, above the engine oil pan) and allow the coolant to drain.
  4.  



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Fig. Fig. 7: If a complete draining is required, you can remove the engine block's drain plug(s) (see arrow)

  1. Allow the coolant to drain completely from the vehicle.
  2.  
  3. Close the radiator drain valve, then reinstall any block drains which were removed.
  4.  
  5. Using a 50/50 mixture of antifreeze and clean water, fill the radiator to the bottom of the filler neck and the coolant tank to the FULL mark.
  6.  



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Fig. Fig. 8: Fill the radiator to the bottom of the filler neck with a 50/50 antifreeze and water mixture



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Fig. Fig. 9: Also, make sure to fill the coolant recovery reservoir

  1. Install the radiator cap, making sure the arrows line up over the overflow tube leading the reservoir or surge tank. Place the cap back on the recovery bottle or surge tank.
  2.  
  3. Start the engine. Select HEAT on the climate control panel and turn the temperature valve to full WARM. Run the engine until it reaches normal operating temperature. Check to make sure there is hot air flowing from the floor ducts.
  4.  
  5. Check the fluid level in the reservoir or surge tank and add as necessary.
  6.  
  7. If necessary, you can pressure check the cooling system for leaks.
  8.  



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Fig. Fig. 10: Cooling systems should be pressure tested for leaks periodically

FLUSHING & CLEANING



Several aftermarket radiator flushing and cleaning kits can be purchased at your local auto parts store. It is recommended that the radiator be cleaned and flushed of sludge and any rust build-up once a year. Manufacturer's directions for proper use, and safety precautions, come in each kit.

  1. Refer to the drain and refill procedure in this section, then drain the cooling system.
  2.  
  3. Close the drain valve.
  4.  

A flushing solution may be used. Ensure it is safe for use with aluminum cooling system components. Follow the directions on the container.

  1. If using a flushing solution, remove the thermostat. Reinstall the thermostat housing.
  2.  
  3. Add sufficient water to fill the system.
  4.  
  5. Start the engine and run for a few minutes. Drain the system.
  6.  
  7. If using a flushing solution, disconnect the heater hose that connects the cylinder head to the heater core (that end of the hose will clamp to a fitting on the firewall. Connect a water hose to the end of the heater hose that runs to the cylinder head and run water into the system until it begins to flow out of the top of the radiator.
  8.  
  9. Allow the water to flow out of the radiator until it is clear.
  10.  
  11. Reconnect the heater hose.
  12.  
  13. Drain the cooling system.
  14.  
  15. Reinstall the thermostat.
  16.  
  17. Empty the coolant reservoir or surge tank and flush it.
  18.  
  19. Fill the cooling system, using the correct ratio of antifreeze and water, to the bottom of the filler neck. Fill the reservoir or surge tank to the FULL mark.
  20.  
  21. Install the radiator cap, making sure that the arrows align with the overflow tube.
  22.  

 
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