BMW N62 Water Pump Replacement – 8 Cylinder 5,6,7 and X5 Series

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BMW N62 Water Pump Replacement – 4 Hours
Advanced repair level
Repair cost level 1
The BMW Repair Guide used this 2005 645ci for the following article.
Repair Summary
This article gives detailed instructions on replacing the water pump in a BMW vehicle with the N62 8 cylinder engine. Even though we used a 2005 645ci to perform this repair, this article can be applied to any vehicle with the N62 8 cylinder engine including V8 5,6,7 and X5 series vehicles with minor modifications to the repair steps.

A BMW N62 water pump replacement can help cure an overheating engine.

The BMW N62 V8 engine was the workhorse of all 8 cylinder E6x 5 series, E6x 6 series, E6x 7 series and E53 X5 series vehicles produced till approximately 2010. It was the direct successor to the iconic M60/M62 V8s produced during the 1990’s and early 2000’s. The New Generation N62 V8 was produced with many enhancements to help increase fuel economy and decrease emmissions…one of them being an improved coolant flow circuit  to help reduce engine heat.

The BMW N62 engine was produced with a map-controlled thermostat attached to a pulley driven mechanical water pump located on the front of the engine. The BMW N62 water pump pushes coolant through a feed pipe to the rear of the engine block where it is drawn through the cylinder walls and heads and back to the thermostat housing. Cold coolant continues to circulate only through the engine block until the vehicle reaches operating temperature (85°C-110°C) – at operating temperature the thermostat opens allowing hot coolant to circulate through the radiator.

BMW N62 waterpump and thermostatThe effects of a failed water pump are obvious – coolant is no longer circulated through the engine block causing immediate vehicle overheating and possible catastrophic engine damage. One of the main causes of water pump failure in the N62 V8 engine is simply due to age. The mechanical N62 water pump has a definitive lifespan and eventually will wear out. The BMW Repair Guide recommends replacing your N62 V8 water pump every 100,000 miles. Water pumps are also prone to coolant leaks around their gaskets. Heat and age cause the water pump gaskets to become brittle, allowing coolant to seep down the front of the engine creating a puddle under the front of the vehicle. If the you suspect your water pump is leaking, it is best to go ahead and replace the entire unit.

The BMW Repair Guide strongly recommends also replacing the thermostat when performing a BMW N62 water pump replacement.

A BMW N62 water pump replacement is fairly straightforward except for one issue – the water pump’s lower mounting bolt is located behind the harmonic balancer pulley. You must unfortunately remove the harmonic balancer pulley in order to access and remove this bolt. Although it is not technically challenging to remove the harmonic balancer pulley, it does require jacking up the front of the vehicle so the AC drive belt can be removed.

We give full step by step instructions below on how to perform a BMW N62 water pump replacement, along with a detailed parts list for your convenience. Please remember that you will lose approximately one gallon of engine coolant during this repair.

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1. Water Pump (required) – The BMW Repair Guide recommends always using an OEM quality water pump when doing this repair. Cheap “generic” branded water pumps have a high failure rate and are not worth the couple dollars in savings. We give you several excellent choices based on your budget and brand preference.

2. Coolant return pipe (required) – The BMW Repair Guide recommends always replacing the small coolant return pipe when replacing your water pump. The coolant return pipe sits behind the water pump and is a common source of leaks. Replacing your coolant return pipe will help ensure your new water pump stays leak free.

3. Antifreeze/Coolant (required) – You will lose about one gallon of coolant when doing this repair. It is recommended that you only use Genuine BMW Antifreeze/Coolant mixed 50/50 with distilled water in your vehicle.

4. Thermostat (optional) – Although not required, it is highly recommended that you replace your thermostat with the water pump. The thermostat housing is attached to the water pump on the N62 V8 engine and must be removed during this repair. Installing a new thermostat is cheap insurance against future issues with your cooling system.

Section 1 – Removing the BMW N62 water pump.

As discussed above, removing the BMW N62 water pump is fairly straightforward with one caveat – the harmonic balancer pulley must be removed to access the lower water pump mounting bolt. In most cases this will require jacking up the front of the vehicle so the AC drive belt can be removed (all drive belts must be loosened for this repair).

  1. Use a T27 torx bit to remove the upper engine cover. Use a T27 torx bit to remove the upper engine cover boltsbmw n62 water pump replacement - Remove the upper engine cover from the vehicle.
  2. Unplug the mass air flow (MAF) sensor.Unplug the mass air flow (MAF) sensor.
  3. Disconnect the vacuum line from the intake boot.bmw n62 water pump replacement - Disconnect the vacuum line from the intake boot
  4. Unsnap the intake muffler lid. Loosen the hose clamp on the intake boot where it attaches to the throttle body. Grasp the lid and the boot and remove them from the vehicle.bmw n62 water pump replacement - Unsnap the intake muffler cover.bmw n62 water pump replacement - loosen the hose clamp where the intake boot attaches to the throttle body.bmw n62 water pump replacement - Remove the intake muffler lid.
  5. Locate the thermostat on the front of the engine and unplug its heating element.Unplug the thermostat sensor.
  6. Locate the water pump and unplug the coolant temperature sensor.Unplug the coolant temperature sensor
  7. Position a large drain pan under the vehicle. You will lose about 1/2 gallon of coolant when you remove the thermostat.bmw n62 water pump replacement - Position a drain pan under the thermostat to catch the coolant.
  8. Using a small flat blade screwdriver, lift the metal locking clip on the radiator coolant return hose and pull it free from the thermostat.bmw n62 water pump replacement - Remove the coolant return hose from the thermostatPull the coolant return line free from the thermostat
  9. Remove the secondary air pump pressure hose clamp from the top of the thermostat. This will make removing the thermostat much easier. bmw n62 water pump replacement - Remove the secondary air pump pressure hose bracketThe secondary air pump pressure hose bracket
  10. Use a small flat blade screwdriver or metal pick to lift the locking clip on the radiator coolant return hose where it attached to the water pump. Grasp the return hose and pull it loose from the pump. bmw water pump replacement - Release the locking clip on the radiator coolant return hosebmw water pump replacement - Remove the coolant return hose from the water pump
  11. Next, the bolts on the water pump pulley need to be loosened (DO NOT remove them yet). You must loosen the bolts now with the main accessory belt still on to keep the pulley from spinning.Loosen the water pump pulley bolts
  12. Locate the main accessory belt tensioner. Remove its dust cap with a flat blade screwdriver.bmw water pump replacement - Remove the dust cap from the tensioner pulley
  13. Use a T50 torx bit to retract the tensioner pulley by turning it clockwise. Grasp the accessory belt and pull it loose. bmw water pump replacement - Use a T50 torx bit to turn the pulley clockwise and retract itbmw water pump replacement - Remove the drive belt from the water pump pulley
  14. Finish removing the water pump pulley bolts. Remove the water pump pulley from the vehicle. Finish removing the water pump pulley mounting bolts with your fingersbmw water pump replacement - Remove the water pump pulley from the vehicle
  15. Use a flat blade screwdriver or metal pick to release the metal locking clip on the lower water pump/radiator return hose. Pull the hose free from the water pump.Release the lower coolant return hose from the bottom of the water pump and remove it
  16. We like to remove the thermostat before the water pump…this allows the cooling system to drain with less mess and provides more room to remove the “hard to reach” lower expansion tank return hose.
  17. Use a 10mm socket wrench to remove the three thermostat mounting bolts. Grasp the thermostat and remove it from the vehicle. Let the system thoroughly drain before moving to the next step. bmw n62 water pump replacement - remove the thermostat mounting boltsbmw n62 water pump replacement - Remove the thermostat from the water pump
  18. With the thermostat removed, you can now easily access the lower expansion tank return hose. Use a flat blade screwdriver or metal pick to release its locking clip. Pull the return hose free from the water pump. Release the locking clip on the lower expansion tank return hosebmw n62 water pump replacement - Remove the expansion tank return hose from the water pump.
  19. Next, the five water pump mounting bolts must be removed. Start at the top of the engine and remove the four that can be reached. The final fifth bolt is behind the harmonic balancer pulley and cannot be reached until step 23 below.bmw water pump replacement - Remove the upper four mounting bolts from the water pump
  20. With the top four bolts removed, move to the bottom of the vehicle and locate the AC drive belt. There are two versions of AC drive belts on the N62 V8 engine; the stretch style belt and those with a belt tensioner. Our 2005 645ci originally had a stretch belt, but we performed a belt tensioner retrofit to eliminate it some years back. We find stretch belts to be a pain…hence the reason we performed a retrofit. If you are interested in replacing your stretch belt with the easier best tensioner system, NOW is the time to do it! Please see our article BMW N62 AC Belt Tensioner Retrofit – Stretch Belt Delete – 8 cyl. for more information.
    bmw n62 water pump replacement - locate the ac drive belt
    The AC drive belt on a 2005 645ci. Note that the original “stretch” style belt was retrofitted with a belt tensioner.
  21. Stretch belts – Use a stretch belt tool to remove the AC belt off of the AC compressor. bmw e63 belt replacement - stretch belt installation toolLoop the stretch belt under the AC pulley and hold in place with the installation tool.
  22. Belt tensioner – Locate the AC belt tensioner. Use a torx bit to turn the tensioner counter-clockwise until you can slip the belt off of the AC compressor pulley. Remove the belt from the ac compressor and the harmonic balancer pulley.bmw water pump replacement - Turn the ac belt tensioner counterclockwise to release pressure on the beltRemove the ac belt from the ac compressor and the harmonic balancer pulley
  23. Next, the harmonic balancer pulley must be removed so the final water pump bolt can be accessed. The harmonic balancer is anchored to the engine’s crankshaft with eight bolts. The easiest way to access these bolts is from the top of the engine. Use a T45 torx bit and a socket wrench to remove the eight bolts and remove the harmonic balancer pulley from the vehicle. bmw water pump replacement - The harmonic balancer pulley mounting boltsUse a T45 torx bit to remove the eight harmonic balancer pulley boltsRemove the harmonic balancer from the vehicle.
  24. With the harmonic balancer pulley removed, the final water pump bolt can be removed.bmw water pump replacement - Remove the lower water pump mounting bolt
  25. Grasp the water pump and pull it loose from the engine. If it is stuck like ours was, use a long flat blade screw driver to gently pry it off as shown below. bmw water pump replacement - Grasp the water pump and pull it loose from the engine blockbmw water pump replacement - Use a large flat blade screwdriver to pry the water pump loose if it is stuckRemove the water pump from the vehicle
  26. Grasp the short coolant return pipe and remove it from the engine. This pipe should always be replaced when performing a BMW N62 water pump replacement. bmw water pump replacement - Grasp the return coolant pipe and remove it from the engineThe return coolant pipe
Section 2 – Installing the new N62 water pump.

Installing the new N62 V8 water pump is very straight forward…it is simply the above steps in reverse without any special procedures. We do recommend adding a small amount of liquid dish detergent to the water pipe o-rings to help them slide into the water pump easier. NEVER USE petroleum based oil or grease on the rubber o-rings (they can dame them and cause potential leaks). We have provided a handy checklist below with the installation steps and important torque values.

BMW N62 Water Pump Installation Checklist

When you are finished with a step, use your mouse (or finger if on mobile) to check the box as completed! Completed step =
***The following steps were performed on a 2005 BMW 645ci…other models may vary. 

  • Install a new return coolant pipe. Apply a small amount of liquid dish detergent to its rubber o-rings if necessary to help it slide into place. DO NOT use petroleum based oils or grease.
  • Make sure there is a new rubber gasket installed in the new water pump.
  • Install the new water pump. make sure it is firmly seated on the coolant pipes.
  • Install the five water pump mounting bolts and torque to 10.5 Nm (7.75 ft-lb).
  • Reinstall the harmonic balancer pulley. Torque its eight mounting bolts to 25 Nm (18 ft-lb).
  • Reinstall the AC drive belt.
  • Install the lower expansion tank return hose. Make sure you hear it click into place on the water pump.
  • Reinstall the thermostat and torque its three mounting bolts to 10.5 Nm (7.75 ft-lb).
  • Reinstall the lower water pump/radiator return hose.
  • Install the water pump pulley. Hand tighten its four mounting bolts (they will be torqued after the main accessory belt is installed).
  • Reinstall the main accessory belt.
  • Torque the four water pump pulley bolts to 10.5 Nm (7.75 ft-lb).
  • Reattach the radiator coolant return hose to the top of the water pump.
  • Reinstall the secondary air pump pressure hose bracket to the top of the thermostat.
  • Reattach the radiator coolant return hose to the thermostat.
  • Plug the thermostat heating element back in.
  • Plug the water pump coolant temperature sensor back into the water pump.
  • Reinstall intake muffler lid. Make sure the intake boot hose clamp is secure.
  • Reconnect the vacuum line to the intake boot.
  • Plug the mass air flow sensor back in.
  • Replace the upper engine cover.
BMW N62 Water Pump Replacement Finished
If you have any questions or comments, please feel free to contact us. And congratulations for Doing It Yourself!