MazdaRx7Power

is their anyway to prevent water cavation or whatever its called? does it happen if the water pump housing is rusty and stuff inside or does it happen even if u have a new water pump housing? cause i have the double sleeve alternator pulley but still overheats whenever hailing ***. still havent gotten the main underdrive pulley! will it make a big difference? i know it adds HP but does it make a difference in the over temp of the car? and is it an easy bolt on or do u have to do something special cause i remember somebody mentioning something about the eccentic shaft can be damaged or something like that what u guys think?

adeckbar

i had the same problem on my 86 gxl the underdrive pulley on the ecc. should help by slowing the water pumps rpm in relation to the stock pulley rpm you can also help by rasing the pressure on the radiator cap

copandengr

Cavitation is essentially reducing the pressure on water until it begins to boil at what ever temperature it happens to be. You can boil water at room temperature if you reduce the atmospheric pressure enough. Most 8th grade science classes do this in a vacuum jar with a pot of water in it. This is also why you need to pull a vacuum in an air conditioning system before charging it. The idea is to "boil" off the water in the A/C components.

Cavitation happens in a water pump when the impeller is spinning too fast for the water to follow it. When this happens, you have minute areas around the impeller blades where the pressure is so low the water is boiling. The impellers become surrounded by what amounts to air, and no coolant is moved. This creates not only the problem of proper circulation of the coolant, but another equally serious problem as well. When the coolant boils, it releases tremendous shock waves as the bubbles implode. Listen to a pot of boiling water on your stove to hear this. It is a series of micro shock waves that will eventually eat away at the impeller blades untill there is nothing left of them.

The only solution to this is to slow the speed of the water pump down to a limit which is under that where cavitation happens. You are on the right track with the underdrive pulley idea.

Scott 89t2

another cause of cavitation is a weak lower rad hose which will collapse at higher rpm. if it feels soft replace it. adding a spring will also help a bit.

what kind of rpm are you driving at?? cavitation usaly happens holding a constant high rpm.