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Auxiliary Coolant Pump Replacement
 
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Pelican Technical Article:

Auxiliary Coolant Pump Replacement

Nick Czerula

Time:

3 hour3 hr

Tab:

$400

Talent:

***

Tools:

Set of sockets, screwdrivers, hose pliers

Applicable Models:

BMW Z4 Coupe/Conv (2006)

Parts Required:

Auxiliary coolant pump, engine coolant

Hot Tip:

Work with a cool engine

Performance Gain:

Car will cool down again, coolant leak repaired

Complementary Modification:

Change the radiator hoses and flush the cooling system

BMW Z4 models are equipped with a climate control system or HVAC (called IHKA by BMW) that automatically controls cabin temperature once a temperature is set on the HVAC control head in the center dashboard. IHKA controls air-conditioning, heating, internal blower motor operation and numerous air outlets. The electronic IHKA control module governs the operations of the following components:

  • Auxiliary coolant pump in engine compartment, controls the flow of hot coolant to the heater core inside the IHKA housing underneath the center dashboard.
  • AC compressor in the engine compartment, driven by engine accessory belt
  • Blower motor underneath the dashboard behind the glove compartment, motor speed modulated using the blower final stage
  • Air outlets, electric stepper motors attached to vent flaps control the flow of fresh or recirculated cold and warm air to windshield, face-level vents and foot wells
  • Engine cooling fan, IHKA microprocessor and engine control module (ECM) determine operation and speed of cooling fan

The auxiliary coolant pump that controls the flow of hot coolant to the heater core in the IHKA housing under the dashboard. If your vehicle has no heat and the cooling system is properly bled, the pump may be faulty.

A quick check is to warm the vehicle up and then turn the heat ON; both heater hoses should be hot to the touch. If one hose is cool and the other is hot the pump is not allowing coolant flow. You could also have a bad signal to the pump; it is a two-wire circuit. Using a wiring diagram, you can identify the ground and battery positive feed to the pump, and test for proper voltage when the heat is ON.

Do not remove the radiator or expansion tank cap or work on any other part of the cooling system while the engine is hot. Coolant or hot steam may escape and will scald you. To do any work on the cooling system, wait until the engine has cooled off.

To avoid marring the paint and trim, work with a plastic prying tool or wrap a screwdriver tip with masking tape before prying out body or interior items.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

This photo shows the location of the auxiliary coolant pump (red arrow).
Figure 1

This photo shows the location of the auxiliary coolant pump (red arrow). It is located at the left side of the frame, below the intake air duct. To access the pump, start by removing the intake air housing. See our tech article on intake air housing replacing. Drain the cooling system. See our tech article on cooling system draining and filling.

Working at the auxiliary coolant pump, press the release tab and pull the connector (red arrow) straight off to remove it (inset).
Figure 2

Working at the auxiliary coolant pump, press the release tab and pull the connector (red arrow) straight off to remove it (inset).

Working at the rear of the pump, remove the hose clamp.
Figure 3

Working at the rear of the pump, remove the hose clamp. Use pliers to slide it down the hose about three inches away from the end of the hose (red arrow). Then remove the hose from the pump.

Then, pull the pump out of the mount.
Figure 4

Then, pull the pump out of the mount. Pull the pump straight up (red arrow) to remove it. Be careful not to lose the rubber mounting grommets. Working at the bottom of the pump, remove the hose clamp (green arrow). Use pliers to slide it down the hose about three inches away from the end of the hose. Then remove the hose from the pump.

Transfer the rubber mounting grommets over to the new pump if necessary.
Figure 5

Transfer the rubber mounting grommets over to the new pump if necessary. Reverse these steps to install the new pump. Fill and bleed the cooling system. Once complete, double check all the hose connections and check the engine for coolant leaks.

The auxiliary coolant pump controls the flow of hot coolant to the heater core in the IHKA housing under the dashboard.
Figure 6

The auxiliary coolant pump controls the flow of hot coolant to the heater core in the IHKA housing under the dashboard. If your vehicle has no heat and the cooling system is properly bled, the pump may be faulty. Check if the impeller (red arrow) is seized. It should move around by hand.





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Page last updated: Sat 12/3/2016 02:56:13 AM