I need help! My water pump is occasionally cavitating when I am over 6K RPM.
Three questions:

Why is it doing this?
Will it harm something?
How do I make it stop?

Oh yeah, my car is a 1991 RX7 convertible with 64K miles and she is completely stock.


thanks,
Kris

 

1. How do you know it is doing so? It normally happens to most water pumps at higher rpms.
2. It may affect cooling if you are constantly in high revs.
3. best idea: underdrive the water pump via pulley on the crank (this will also underdrive the alternator). $70-100
Expensive idea: Electric water pump. Expensive to set up, debatable for street use, $300-1000, better cooling at alkl rpms, programamble...

I run the latter.
Sean Cathcart

 

I can hear it making the sound of bubbles wooshing through water, and I assumed that is what it would be. Could it be something else?

thanks,
Kris

 

i cant hear myself think when the motor is above 6k let alone hear bubbles! Try turning your heater on, see if you hear bubbling (at idle is fine). You might just have air in the system.

 

Do you mean have the heater on when revving over 6K RPM?

 

How in the heck can you hear bubbles at 6K rpm? good lord.

Anyway, you might be right, it might be cavitating, and prolonged time at 6K rpm will reduce coolant flow and begin the death dance with temps climbing.. My question,why are you spending a lot of time at 6k? if not, I wouldn't stress about it, but if you absolutely have to fix this, then scathcart's recommendations are 100% spot on, with one addition. If you remove everything on the engine (Air pump, PS pump, AC compressor) driven bya belt, look for a 2 groove alternator pulley and install, or the belts may not spin the water pump as much as needed at high RPM.

PaulC

 

Right silkworm. Damn it, I thought I had a complete post!
A cheaper fix is the 3L220 lawnmower belt slipped over the crank and the water pump pulley. This offers MUCH more contact area than a dual sheave alternator.
Sean

 

My car is VERY quiet (completely stock), and I can hear every little sound she makes. I drive her pretty hard, and I often rev up to 6 or 7K. Redline is 8K. Is what I am hearing the water pump?

thanks,
Kris

 

Is it even possible to hear the water pump cavitating, or am I hearing something else (ie the heater core)? Remember, my car is extremely quite.

thanks,
Kris

 

Is your name Superman?


-Ted

 

Well Ted, what am I hearing?

 

no, he's aquaman he's hearing bubbles under water

 

with several second gen race cars turbo and N/A that are run constantly over 6000 rpm and sometimes near 10000 rpm I have not had any problems with water pump cavitation. the noises you are hearing is probably air trapped in the system that is being moved around and making noise. try to bleed the system again making sure the heater is on while doing this. if the engine is over heating and you suspect this problem then do a pressure test to see if there is a leak in the system first. noise could be from exhaust gasses entering the cooling system also. if the car is running fine and not overheating I would not worry or invest to much in a "fix".