I went to the parts store last week to purchase a new water pump for my S5 NA and was surprised to discover that the pump is very heavy. Is the water pump for the S5 supposed to be made of cast iron?

Is there a good source for water pumps online?

Also I keep reading today about electric water pumps. I've never heard of them before; they seem conceptually much simpler but I would expect the extra strain on the alternator to be a negative. Why are electric water pumps not popular like electric fuel pumps are?

 

dont use an electric water pump, stay with the mechanical, much simpler and less hassle

 

Call Ray Crowe at Malloy Mazda and get an OEM reman pump. I think mine was something like $60 shipped once I shipped back the core. (703) 490-8170 ask for Mazda Parts, ask for Ray Crowe. he's there 8-4 PM eastern

There's nothing wrong with electric water pumps, but I don't trust them on Rx-7 applications. BMW uses electric pumps on their current engines, and the pumps are duty controlled by the ECU. But those are OEM electric pumps engineered by guys in lab coats, built for motors that were intended to have them. They're not aftermarket pumps designed in somebody's garage as replacements for existing reliable OEM parts.