Water Pump

From BMW E34 Encyclopedia

Overview[edit]

In this section, we will cover inspection of the water pump and basic replacement procedure.

Inspection[edit]

  • Inspect the water pump for visible leaks at gasket and thermostat level
  • If the thermostat fails to open, the hose leading to the pump from the radiator (passenger side) will get extremely hot at a normal operating temperature
  • Check the fan clutch for wobble. Take the belt off and check the pulley for play in all directions. There should no play in either direction
  • The pulley should be spinning with slight resistance and stop after a couple of turns. Free spinning indicates excessive wear

Video Walkthrough[edit]

Parts Required[edit]

  • A brand new water pump with a metal impeller. The pump should come with a gasket and 2 pipe o-rings. This component is critical to the vehicle operation and lifespan. Only use OEM or a quality aftermarket replacement
  • 2 gallons of a BMW coolant and 2 gallons of distilled water
  • Good silicon gasket maker for the water pump
  • Blue Locktite

Optional Parts[edit]

While doing this job, you can also replace following:

  • Fan clutch (highly recommended)
  • Upper and lower radiator hoses (highly recommended)
  • V-Belt and A/C belt
  • Both tensioners
  • Idler, adjusting, water pump, and power steering pulleys

Tools Required[edit]

  • Drain pan
  • 10mm, 12mm, 13mm, and 17mm sockets
  • Two ratchets with short and longer extensions
  • Rubber mallet
  • 32mm thin wrench
  • Torque wrench
  • Screwdriver

Torque Specifications[edit]

  • Pulley to the water pump: 10 nm
  • Vibration damper to the crankshaft: 22 nm
  • The thermostat housing to coolant pump: 10 nm
  • Water pump to the timing chain cover 10 nm

Replacement[edit]

  1. Jack up the car
  2. Make sure the car is secured with jack stands and the rear wheels are chocked
  3. The vehicle should be completely cold. Place a drain pan under the driver side of the radiator and remove the drain plug. The plug is located on the bottom right side of your radiator (driver side).
  4. The fan clutch threads are reverse threaded
  5. Put a 32mm thin wrench on the fan clutch bolt (connected to the pump), and hold the water pump pulley with your hand while applying counter-clockwise pressure on the wrench to loosen up the bolt
  6. Try giving the wrench a wack or two with a rubber mallet to get things moving
  7. If the bolt is rusted or stubborn, you may need to get a special BMW pulley holder
  8. Once the bolt is off, spin the fan (counter-clockwise) until it slides off the threads. Make sure to catch it with your hands to prevent damage to the plastic blades
  9. Relief tension from the V-Belt and take it out
  10. Jack the car back down
  11. Remove the upper radiator (return) hose from radiator to engine block
  12. Remove the smaller (bleed) hose that runs from coolant reservoir to the top corner of the radiator
  13. Remove the lower radiator hose from radiator to the water pump
  14. Unplug the temperature sensor from the passenger side of radiator
  15. Push the radiator down and release two top side clips that secure the radiator to the frame
  16. Take out the radiator and safely place it away from the vehicle
  17. You may want to run a radiator cleaner or a water hose to clean out potential debris
  18. Using a rachet with a small extension unscrew all of the 13mm x 8 bolts from the harmonic balancer. Use a bigger rachet and tap it with a rubber mallet to loosen up the bolts
  19. Use the mallet to give a couple of love taps to the harmonic balancer, then take it off by pulling it forward
  20. Remove all of the 10mm bolts from the water pump. There are 2 long bolts located on the top left of the pump. The bolts should be opposite to each other. Note and label their position

Be careful as you do not want to unplug the metal pipes from the rear. You want to disconnect them from the pump as you pull it out instead!


  1. Hold the water pump and tap it lightly with a mallet, then carefully pull it forward while holding the two rear pipes in place
  2. Remove the water pump. Then take a sharp razor blade and scrape everything off the block. Spray a carb cleaner if necessary
  3. If you are also replacing the thermostat, put it on the new water pump (use blue Locktite). Use a silicon gasket (made for water pumps) where the thermostat makes contact with the pump
  4. Transfer (or use a new) water pump pulley to your new water pump
  5. Liberally apply the silicon gasket maker around the gasket mating surface (on the pump itself). Go around the bolt holes. Apply it to the top of the two pipes sticking out of the engine
  6. Put a new water pump gasket on top of the silicon you just applied and press it until it sticks
  7. Now the fun part. You have to put the new water pump back in straight and align all of the bolts while also aligning it with the engine (coolant) pipes. Careful to not to move the gasket you just attached.
  8. This might take few attempts. The trick is to have two longer bolts nearby with proper lighting. Slowly put the bigger pipe in the water pump first, then carefully maneuver the pump into a smaller pipe
  9. Slowly push the pump back to it is the place while looking at the bolt holes to gauge alignment. Do not force it
  10. You will feel feedback when the pump makes full contact with the rear coolant pipes
  11. Quickly put the two longer bolts back on the pump, and inspect both sides of water pump for misalignment. The gasket should not be sticking out
  12. You can repeat this procedure until the gasket is properly aligned
  13. The rest is reverse of removal. Use the blue Locktite on all of the water pump and harmonic balancer bolts

Bleeding[edit]

Review our coolant bleeding procedure