BMW 318/325/M3/525/535/M5 1989-1993 Repair Information

Cooling System

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BMW recommends that the coolant be changed every 2 years. Collect your used coolant in a clean pan, do not allow any other fluids to mix with it, and return it to a recycling facility or shop. Do not drain the coolant on the ground or pour it into a sewer.

FLUID RECOMMENDATIONS



BMW recommends that an ethylene glycol based antifreeze coolant be used. Stay with a name brand that is compatible with aluminum and is nitrate and amino free. The coolant should be a 50/50 mix to achieve protection to -35°F. (-37°C.). Any concentration in excess of 50/50 will actually reduce the effectiveness of the fluid as a heat transfer medium.

LEVEL CHECK



See Figures 1, 2 and 3



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Fig. Fig. 1: Coolant expansion tank is translucent for easy level checks



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Fig. Fig. 2: Integral coolant expansion tank is translucent for easy level checks



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Fig. Fig. 3: Bleeder is located next to radiator cap. Check the radiator cap gaskets when removed

BMW vehicles are equipped with translucent coolant expansion tanks. There will be marks indicating "MAX" and/or "COLD" levels. There is no need to remove the fill cap from the expansion tank. Do not remove the fill cap unless coolant needs to be added to the system.


CAUTION
Do not remove the expansion tank fill cap with the engine still hot. Allow the engine to cool, then remove the cap. Coolant can ignite if spilled onto an overheated engine. Do not add coolant to a hot engine. The temperature differential between the hot metal and the cold coolant can cause warpage, boiling splash back and other damage to the engine or personal injury.

ADDING COOLANT



Except M5

If coolant needs to be added to the system, allow the engine to cool and remove the fill cap in a counterclockwise direction to the first stop. This will allow any pressure in the system to escape. Completely remove the cap, add the required coolant to the expansion tank and replace the cap.

M5
ENGINE COLD

With the engine cold, not warm, but cold, remove the cap on the expansion tank and top up to the "COLD" mark. If the system required more than 1.1 quarts (1 liter), follow the Engine Warm procedure.

ENGINE WARM

If the engine is warm with the temperature gauge reading in the lower third of its range, follow this procedure. Do not attempt to fill the system until the temperature gauge is reading in the lower third of its range.


CAUTION
The M5 cooling system is a pressurized system and requires a specific method of adding coolant. If the fill cap is removed while the engine is still warm, above the one third mark on the temperature gauge, a risk of scalding and severe burns exists.

  1. Allow the engine to cool until the temperature gauge is in the lower third of its range.
  2.  
  3. Turn the cap counterclockwise to the first stop and allow any pressure to escape. Remove the cap fully.
  4.  
  5. Fill the expansion tank to the "MAX" marking.
  6.  
  7. Start the engine and press the side and window defroster button on the climate control panel.
  8.  
  9. Loosen the cooling system bleeder valve located near the remote positive battery connection. Allow any air to escape and tighten.
  10.  
  11. Refill the expansion tank to the "MAX" mark and run the engine at 2500 rpm.
  12.  
  13. When the level in the expansion tank steadies itself at the "MAX" mark, replace the fill cap.
  14.  
  15. If the expansion tank is equipped with an air fill valve, use a tire pump to pressurize the cooling system at the fill valve on the expansion tank to 7 psi (0.5 bar).
  16.  


WARNING
If the system is not pressurized, engine damage will occur. The system is designed to be precisely pressurized. If the system cannot be pressurized at the moment, avoid driving the vehicle or limit the engine speed to 3000 rpm or less until the first possible opportunity to restore the pressure.

  1. If the expansion tank is not equipped with an air fill valve, check the present coolant level, then allow the engine to cool for at least 6 hours and recheck the level. The coolant level should be between the "COLD" and "MAX" marks with the engine warm and be at the "COLD" mark when cold.
  2.  
  3. If the level has to be adjusted, remove the cap and add the required amount. If the amount was in excess of 1.1 quarts (1 liter) repeat this procedure.
  4.  

DRAIN AND REFILL



  1. Allow the engine to cool completely. Turn the cap counterclockwise to the first stop and allow any pressure to escape. Remove the cap fully.
  2.  
  3. Loosen the bleeder screw on the radiator on vehicles with integrally mounted expansion tanks.
  4.  
  5. Remove the splash shield from under the vehicle to access the radiator drain plug.
  6.  
  7. Remove the drain plug and catch the used coolant in a clean container. Return the used coolant to a recycling facility or shop.
  8.  
  9. Replace the drain plug and tighten to 1.1-1.9 ft. lbs. (1.5-3.0 Nm).
  10.  
  11. Add a 50/50 mix of coolant to the expansion tank and bleed the system.
  12.  

SYSTEM BLEEDING



The cooling system must be bled to remove air from the coolant passages. If the system is not bled, hot spots can form leading to overheating and engine damage.

INTEGRAL EXPANSION TANK SYSTEMS

These systems have the expansion tank as part of the radiator assembly. It is the vertically mounted, translucent tank on the side of the radiator.

  1. With the expansion tank filled with coolant mix, run the engine to operating temperature. Set the heater controls to WARM and engine speed to fast idle.
  2.  
  3. Loosen the radiator mounted bleeder screw. Allow coolant to run out of the bleeder until a solid stream of coolant and no air is coming out. Keep the expansion tank full during this step. Tighten the bleeder screw.
  4.  
  5. Turn OFF the engine, but keep the ignition switch in the ON position. On vehicles with a thermostat housing bleeder screw, open the screw and allow coolant to run out of the bleeder until a solid stream of coolant and no air is coming out. Keep the expansion tank full during this step. Tighten the bleeder screw to 4.5-7.0 ft lbs. (6-10 Nm).
  6.  
  7. Start the engine and run at 2500 rpm. The coolant level will drop to the "COLD" mark on the expansion tank or close to it, indicating that residual air has been purged from the system.
  8.  
  9. Replace the expansion tank cap.
  10.  

REMOTE EXPANSION TANK SYSTEMS
EXCEPT M5
  1. With the expansion tank filled with coolant mix, run the engine to operating temperature. Set the heater controls to WARM and engine speed to fast idle.
  2.  
  3. Loosen the thermostat housing mounted bleeder screw. Allow coolant to run out of the bleeder until a solid stream of coolant and no air is coming out. Do not allow the expansion tank to run dry during this step. Tighten the bleeder screw to 4.5-7.0 ft lbs. (6-10 Nm).
  4.  
  5. Fill the expansion tank to the "COLD" mark. Replace the tank cap.
  6.  

M5
  1. Fill the expansion tank to the "MAX" marking.
  2.  
  3. Start the engine and press the side and window defroster button on the climate control panel.
  4.  
  5. Loosen the cooling system bleeder valve located near the remote positive battery connection. Allow any air to escape and tighten.
  6.  
  7. Refill the expansion tank to the "MAX" mark and run the engine at 2500 rpm.
  8.  
  9. When the level in the expansion tank steadies itself at the "MAX" mark, replace the fill cap.
  10.  
  11. If the expansion tank is equipped with an air fill valve use a tire pump to pressurize the cooling system at the fill valve on the expansion tank to 7 psi (0.5 bar).
  12.  


WARNING
If the system is not pressurized, engine damage will occur. The system is designed to be precisely pressurized. If the system cannot be pressurized at the moment, avoid driving the vehicle or limit the engine speed to 3000 rpm or less until the first possible opportunity to restore the pressure.

  1. If the expansion tank is not equipped with an air fill valve, check the present coolant level, then allow the engine to cool for at least 6 hours and recheck the level. The coolant level should be between the "COLD" and "MAX" marks with the engine warm and be at the "COLD" mark when cold.
  2.  
  3. If the level has to be adjusted, remove the cap and add the required amount. If the amount was in excess of 1.1 quarts (1 liter) repeat this procedure.
  4.  

FLUSHING AND CLEANING



With the use of electrically actuated heater valves and bi-zone heater cores, it is not easy or advisable to cut hoses to mount a flushing tee. Drain the system, add clear water, bleed the system and run the engine to flush the system of old coolant. Drain the system, add fresh coolant and bleed the system. This will get rid of most of the old coolant and keep the cooling system in good shape. It is important to change the coolant on a regular basis, every 2 years, as this will prevent corrosion from building up and creating the need for cleaning the cooling system.

 
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