The water pump or more specifically the coolant pump is vital for your car’s “good health”.  It is responsible for maintaing the engine at optimal operating temperature.

The pump is driven by the Poly-Ribbed Belt, which also drives the Alternator, the A/C and the Power Steering.

In most cases, when the water pump fails, it’s the impeller which breaks due to pump’s bearing which eventually breaks.  When this happens generally the Poly-Ribbed Belt shreds or comes off the pulleys and or the engine looses its coolant.  Immediately stop the engine and have the vehicle towed.  If the engine continues to run with no coolant, it may seize causing irreparable damage.  Also, without the belt in place, the steering will be very hard and the battery will be drained quickly, as the alternator won’t recharge.

These are the tools you’ll

need to get the job done:

• Hose clamp tool (or pliers)

• 7 mm socket

• 10 mm scket

• 5 mm hex Alllen wrench

• Assorted flat-blade screw        drivers

You’ll also need a 5 Gallon bucket

to collect the old coolant mix.

Assorted metric sockets will also be needed to remove/replace the front engine mount.

You can use the Porsche coolant, as well as any other high-quality, nitrite, phosphate and silicate free coolant on the market.                                  

The Porsche Boxster, depending on model year, has a coolant capacity of nearly 5 Gallons.

So, you’ll need 3 Gallons of Coolant and 3 Gallons of distilled water (or 6 Gallons of coolant mix 50/50).

Although most of the coolant will have been lost, if the impeller broke, please refer to the DIY Project:  Flush Coolant System. for additional instructions on coolant draining and refilling.

If the Poly-Ribbed Belt is still in place, remove the aluminum firewall behind the seats and use a 24 mm wrench on the tensioner roller to relieve the pressure and

allow you to move the

belt out from the


If you had a water pump failure where the bearing seized, you may be loooking at a shredded belt.

It is also helpful to consult the DIY Project: Install Front Engine Mount, as I find that replacing the water pump is much easier from the bottom of the car than from the firewall behind the seats.

Make sure that the coolant has been drained.

Remove the Front Engine Mount and lower the engine using a scissors jack as much as possible to give you access to the lower end of the water pump.

Above, you can see the Front Engine Mount, just before removal.  Here the engine has been lowered about 4 inches.

Once the Front Engine Mount is out, you will be able to remove the 7 bolts (10 mm hex) that fasten the water pump in place.  Keep track of where the bolts go, because some are a bit longer than others.

On the left, the new pump, ready to be installed.  On the right, the failed pump.  Note the location of the 7  holes for the 10 mm bolts since they are not all of equal length.

In the case of a failed impeller it is also good to remove the thermostat (photo above) to make sure that there is no debris from the plastic impeller embedded in the thermostat’s spring.

The thermostat is located immediately behind the water pump, on the passenger side.  It is held in place by three, 10 mm hex bolts.

Note that both, the pump and the thermostat use a metal gasket. 

When replacing it, it is always recommended to install a new gasket to avoid leaks.

To install a new water pump gasket, it will need to be trimmed in 3 places as shown in the above photo.  In order to remove the original gasket from the engine, you will also need to trim the old gasket in the same points.

Make sure to clean the engine’s mating surface with solvent and a rag.  It needs to be perfectly clean and free of debris in order for it to make a good seal.

With the gasket trimmed, place it over the new water pump and align.  The old pump should have two guide pins (dowel sleeve) to help hold the gasket in place.  You can transfer them over to the new pump.

To hold the gasket in place and keep it from sliding, thread the top bolt through the gasket, as shown below.

Manually thread each bolt in place and tighten in a star pattern to a torque of 10 Nm (7 ft-lb).

Replace all of the coolant hoses, test for leaks and fill the system with coolant.

Happy Boxstering,


Replace Water Pump