The failure of a water pump is a semi common thing to happen to almost any car. Its failure is caused by a bearing that is required to allow the pump to spin. When this bearing fails the pump collapses and in most cases the pump leaks. If the water pump is run by a belt or chain that also operates the cam shafts or in some way effects the cam shaft timing, the failure of the water pump can cause massive internal engine damage.
This is the case in the CX9, 3.7 Lt v6 engine. The water pump is front and centre on the timing chain. This is an unusual set up for a car, as in most modern vehicles the pump is easily accessible and not vital to cam shaft timing. Most manufacturers built engines knowing the pump would semi regularly need replacing and positioned this so that it didn’t cost thousands of dollars to replace it.
The Mazda CX9 does not share this common sense fitment of the water pump. The water pump is buried deep within the timing cover, the timing chains run off it and when it fails can cause the timing to be thrown to the wind, resulting in the engine internals turning into a blender. The long and the short of it is the water pump failure in a CX9 often destroys the engine.
Replacing one of these water pumps is a bit of an expedition as the timing covers and timing chains have to come off. Cost can be up there as well as most mechanics advise replacing the timing chains and guides whilst you have them off anyway. Labour alone should cost you around the $1000 mark add to that parts including, water pump, timing chains and guides and your unlike to get much change from $2000. Costs can be reduced by purchasing aftermarket timing chain kits however we do not advise this. When it comes to timing chains, genuine is the best way to go. Cutting costs on a component as vital as a timing chain is exceptionally unwise.
Some mechanics remove the whole engine from the car to do this job. Its not necessary but does make the job at least six times easier. It can be done with the engine remaining in the vehicle, it’s just not a great deal of fun.