VW Passat & Audi A4 1990-2000

Cooling System

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FLUID RECOMMENDATIONS

NOTE
The part numbers provided in the following information could change without notice and are provided only as a reference. Always consult your local dealer for the correct lubricant for your vehicle.

All A4 and Passat models are filled with a mixture of water and special phosphate-free antifreeze/coolant at the factory. This antifreeze/coolant has corrosion inhibitors that prevent frost, the formation of chalk and also raise the boiling point of the water. A4 and Passat models up through model year 1996 are filled at the factory with a special antifreeze/coolant, known as "G11", Part No. ZVW 237 102 or G 011 A8 C.

Beginning with the production run of July, 1996, a new type of antifreeze/coolant was introduced, and used in the production of 1997 and later models. This fluid is the G 12 A8D TL 774 D or G 012 A8 D and referred to as "G12". The G12 coolant is easily identified by its red color and is mixed with distilled water at a 50/50 ratio on all USA models and a 60/40 ratio for all Canadian models.


WARNING
The G12 fluid must not be mixed with other types of coolants or additives. A 50/50 mixture of G12 to distilled water is recommended, however in severe cold climates a 60/40 mixture of G12 to distilled water is permissible. DO NOT exceed a coolant mixture greater than 60% for G11 or G12!


NOTE
Typical antifreeze/coolant is bright green in color. The Volkswagen G11 coolant is blue-green, and the Volkswagen G12 coolant is red. It is VERY important to correctly identify which type of antifreeze/coolant your vehicle uses if you intend to adjust the level or replace it completely.


WARNING
DO NOT mix G11 or G12 together, or with any other coolant. Mixing different types of coolant is prohibited.


NOTE
If G12 is mixed with another coolant, it will turn brown in color.

Engine coolant used during recent production:



Vehicles produced until June 1996: G11
 
Vehicles produced from July 1996: G12
 



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Fig. On later models, the installed coolant type is shown on the coolant reservoir-1.8L Passat shown

LEVEL CHECK


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Fig. Coolant level marks on the expansion tank. Early Passat model shown, others similar



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Fig. Unscrew the coolant reservoir cap to add fluid



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Fig. Add only the antifreeze that meets the manufacturer's specifications



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Fig. Caution, the plastic threads on the cap are easily damaged during installation. If the cap does not thread smoothly, remove it, then carefully re-center it and try again. DO NOT FORCE IT!

The coolant reservoir/expansion tank is translucent. If the reservoir is clean, it can be checked without removing the cap. The reservoir has LOW and HIGH level marks. The coolant must be between the two marks when the engine is cold, and slightly above the high mark at normal operating temperature.


CAUTION
NEVER open, service or drain the cooling system if the system temperature is above 100°F (38°C) otherwise serious burns can occur from the steam and hot coolant.

When removing the threaded pressure cap from the reservoir, loosen the cap slightly first. Do NOT attempt to remove it if the coolant temperature is greater than 100°F (38°C). If the coolant begins to hiss or boil, tighten the cap and wait for the engine to cool down.

Some models are equipped with a coolant level warning light on the dash that illuminates when the ignition key is initially turned on as a bulb check feature and under normal conditions turns off once the engine is started. If the coolant level drops below the minimum level when the engine is running, the coolant level warning light will be activated.

The coolant level warning light is a convenient feature, however if the system malfunctions such as having a stuck float the warning light could fail to activate and the engine could overheat resulting in severe mechanical damage. For this reason periodic Inspection of the coolant level in the reservoir itself is highly recommended.

If the coolant level is mildly low, it can be adjusted to the proper level by adding small amounts of distilled water until the coolant reaches the MAX mark on the reservoir. If the coolant level is extremely low, it is recommended that a 50 / 50 mixture of coolant (make sure to use the same type of coolant that is in the vehicle) and distilled water be used to adjust the level in the reservoir. In extremely cold climates, a ratio of 60 percent antifreeze/coolant and 40 percent distilled water can be used to prevent freezing.

In large quantities, simply adding distilled water to the system can dilute the ratio of coolant to water, which reduces the cooling capabilities of the system, and in extreme cases, can cause freezing of the coolant if the vehicle is exposed to low temperatures. If the coolant freezes in the engine, the engine block can (and often times does) crack. To prevent the coolant mixture from freezing, avoid adding large quantities of distilled water to the system if it is low.

Drain & refill

CAUTION
NEVER open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a resealable container. Coolant should be reused unless it is contaminated or is several years old.

1990-97 Passat Models
2.0L Engines


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Fig. Removing the thermostat from the bottom of the water pump



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Fig. View of the thermostat in the housing

On 2.0L 4-cylinder engines, the most thorough way to drain the coolant from the engine is by removing the thermostat. The thermostat is located at the bottom of the water pump housing. The lower radiator hose attaches directly to the thermostat cover/elbow.

  1. Before raising the front of the vehicle, place the temperature control knob/slider to its warmest setting.
  2.  
  3. Raise and safely support the front of the vehicle on jackstands.
  4.  
  5. Some vehicles have a splash shield underneath the vehicle that may obstruct access to the thermostat cover/elbow. Remove the shield if necessary.
  6.  
  7. Place a large drain pan (large enough to contain the entire cooling system contents) under the water pump. Make sure the drain pan is clean, since the coolant should be reused unless it is dirty, or it does not pass a hydrometer test.
  8.  
  9. Using a 10mm socket and ratchet, loosen (but Do NOT remove) the thermostat cover/elbow bolts. Coolant will start to flow from the elbow, so make sure the drain pan is positioned properly.
  10.  
  11. When the coolant stops flowing, remove the thermostat cover/elbow bolts, and set the cover/elbow aside. It's not necessary to disconnect the lower radiator hose. When removing the cover/elbow bolts, hold the cover/elbow in place; then, slowly lower the cover/elbow and hose. The thermostat may stick in place; be careful when removing it, as residual coolant may still be in the engine.
  12.  
  13. Once the thermostat is removed, remove the coolant reservoir cap to drain the rest of the coolant.
  14.  

To install:

  1. Clean and dry the thermostat housing and the rubber O-ring. Examine the O-ring for cracks or damage and replace as necessary.
  2.  
  3. Install the thermostat into the water pump housing on the engine, then fit the O-ring into place.
  4.  
  5. Install the thermostat housing and tighten the bolts evenly. Torque the bolts to 88 inch lbs. (10 Nm).
  6.  


WARNING
Do NOT over torque these bolts or the housing may break.

  1. If equipped, install the splash shield.
  2.  
  3. Lower the vehicle from the jackstands. Make sure the car is level.
  4.  
  5. Loosen the upper radiator hose and begin filling the system (with the proper mixture of coolant and distilled water) through the coolant reservoir. Loosening the upper hose will allow the air to escape and speed the process.
  6.  
  7. When the system will not take any more coolant, squeeze the lower radiator hose several times to force out any trapped air pockets. Tighten the hose and start the engine. Watch for leaks, and add more coolant as required. Don't run the engine too long with the reservoir cap removed or it will boil over.
  8.  
  9. Install the cap and check for normal operation.
  10.  

VR6 Engines

On VR6 engines, a drain plug is installed in the coolant pipe, which runs between the coolant pump and the thermostat housing.

  1. Before raising the front of the vehicle, place the temperature control knob/slider to its warmest setting.
  2.  
  3. Raise and safely support the front of the vehicle on jackstands.
  4.  
  5. Some vehicles have a splash shield underneath the vehicle that may obstruct access to the coolant pipe. Remove the shield if necessary to allow adequate access to the coolant pipe.
  6.  
  7. Place a large drain pan (large enough to contain the entire cooling system contents) under the drain plug. Make sure the drain pan is clean, since the coolant should be reused unless it is dirty, or it does not pass a hydrometer test.
  8.  
  9. Loosen (but Do NOT remove) the coolant drain plug. Push against the drain plug while unscrewing it by hand. When the drain plug is free of the threads, quickly remove it from the coolant pipe, and allow the coolant to drain from the vehicle.
  10.  
  11. While the coolant is draining, remove the coolant reservoir cap; this will allow thorough draining of the system.
  12.  

To install:

  1. Using a new O-ring on the drain plug, install the drain plug into the coolant pipe. Tighten the drain plug to 88 inch lbs. (10 Nm).
  2.  
  3. If equipped, install the splash shield.
  4.  
  5. Lower the vehicle from the jackstands. Make sure the car is level.
  6.  
  7. Using either the drained coolant, or a fresh mixture of the proper type of coolant and distilled water, slowly fill the cooling system through the coolant reservoir. If possible, loosen the upper hose; this will allow the air to escape and speed the process.
  8.  
  9. When the system will not take any more coolant, tighten the hose (if loosened) and start the engine. Watch for leaks, and add more coolant as required. Don't run the engine too long with the reservoir cap removed or it will boil over.
  10.  

1996-00 A4 and 1998-00 Passat Models
1.8L and v6 engines
  1. Before raising the front of the vehicle, set the climate control temperature knob to its warmest setting.
  2.  
  3. Remove the coolant reservoir cap.
  4.  
  5. Raise and safely support the vehicle.
  6.  
  7. If installed, remove the lower engine cover.
  8.  
  9. Place a large drain pan (large enough to contain the entire cooling system contents) under the drain plug or lower radiator hose. Make sure the drain pan is clean, since the coolant should be reused unless it is dirty, or it does not pass a hydrometer test.
  10.  
  11. If the front bumper is removed, loosen the drain plug at the lower front corner of the radiator, near the lower radiator hose.
  12.  
  13. If the front bumper is not removed, remove the retaining clip from the lower radiator hose, and remove the hose from the radiator.
  14.  
  15. Drain the radiator.
  16.  
  17. On 1.8L engines, locate the water pump drain plug near the thermostat housing and engine oil pan on the front of the engine block.
  18.  
  19. On V6 engines, locate the engine block drain at the bottom right rear of the engine near the oil pan and the mating surface of the engine and transaxle assembly.
  20.  
  21. Place a suitable drain pan under the drain plug, and remove the plug.
  22.  



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Fig. The water pump drain plug is located near the thermostat on 1.8L engines



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Fig. Loosen the heater hose near the firewall and slide it forward to open the coolant bleed hole



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Fig. The lower radiator hose is held in place by a retainer. Once the retainer is removed the hose can be removed



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Fig. The 5-valve V6 engines may have a coolant bleed valve under the reservoir on the lower coolant line. It may be necessary to unbolt the reservoir to allow access to the bleed valve



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Fig. If equipped, the location of the front coolant line bleed valve

To refill :

  1. Close the radiator drain plug and/or if removed, install the lower radiator hose.
  2.  
  3. On 1.8L engines, install the water pump drain plug using a new O-ring and tighten to 22 ft. lbs. (30 Nm).
  4.  
  5. V6 engines, install the engine block drain plug using a new O-ring and tighten to 15 ft. lbs. (20 Nm).
  6.  
  7. If removed, install the lower engine shield.
  8.  
  9. On 1.8L engines, remove the grommet retaining clip at the heater core and pull back the grommet.
  10.  
  11. Loosen the heater core coolant hose clamp and slide the coolant hose forward until the bleed hole clears the end of the fitting.
  12.  
  13. Place a suitable drain pan under the vehicle, below the heater hose connection and on the 5 valve V6 models, under the bleed valves.
  14.  
  15. Using the correct mixture and type of coolant, top off the coolant until no air bubbles are released from the bleeder hole at the heater core hoses.
  16.  
  17. Slide the heater hose fully onto the fitting to seal the bleeder hole and tighten the clamp.
  18.  
  19. On 5-valve V6 models, if equipped:
  20.  
    1. Loosen the bleed valve under the coolant reservoir. It may be necessary to release the reservoir and move it aside to access the bleeder, leaving the coolant hoses attached to the reservoir.
    2.  
    3. Top off the coolant until no air bubbles are released from the bleeder, and then tighten it to 15 ft. lbs. (20 Nm).
    4.  
    5. Loosen the bleed valve on the front coolant line, located between the power steering pump and the left side of the cylinder head.
    6.  
    7. Top off the coolant until no air bubbles are released from the bleeder, and then tighten it to 15 ft. lbs. (20 Nm).
    8.  
    9. If removed, reinstall the coolant reservoir.
    10.  

  21. Install the coolant reservoir cap.
  22.  
  23. Make sure the climate control temperature is set to full hot.
  24.  
  25. Start the engine and allow the engine to run at 2,000 RPM for 3 minutes.
  26.  
  27. Allow the engine to idle until the lower radiator hose feels hot.
  28.  
  29. Check the coolant level in the coolant reservoir and top off to the Max level indicator as necessary.
  30.  
  31. If the level is correct, the coolant level should be between the Min and Max indicators once the engine has cooled. If needed, top off the coolant level as necessary.
  32.  

flushing and cleaning the system

On older vehicles equipped with standard coolant/antifreeze, the cooling system should be drained and refilled with new coolant at least every 30,000 miles or 24 months. If desired, a flush system designed specifically for aluminum cooling components should be used. Follow the instructions on the package.

On vehicles with G11 and G12 coolant/antifreeze, (blue-green and red, respectively). Both G11 and G12 coolant is considered a "lifetime" coolant, the manufacturer does not recommend any special cooling system flushing or replacement unless the system has been drained, contaminated, or a cylinder head gasket or cylinder head has been replaced.

If the system is contaminated, drain the coolant and install water. Run the engine until it is hot and drain the water. Install the proper mixture of the recommended coolant.

 
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