Go Back  RX7Club.com - Mazda RX7 Forum > Tech and Performance > Race Car Tech
Reload this Page >

How do you tell if your water pump is cavitating?

Race Car Tech Discuss anything related to road racing and auto X.

How do you tell if your water pump is cavitating?

Old 11-01-04, 03:18 PM
  #1  
Rotary Freak
5 Year Member
Thread Starter
 
Join Date: Jun 2004
Location: Ames, IA
Posts: 2,718
Likes: 0
Received 0 Likes on 0 Posts
How do you tell if your water pump is cavitating?

I took my car (88 SE) out autocrossing yesterday - great fun, I have much to learn (a stock Cavalier beat me).

One of the things I figured out was that 1st gear, at least on this particular course, is a MUCH better option than 2nd. Coming out of corners at 2k RPM doesn't really do much for times.

Anyway, on the last run, I made the whole run in 1st, with the buzzer going off most of the time. It was much faster, but I finished with the stock temperature gauge at almost half (57 seconds of run). That's high enough to make me uncomfortable - it normally runs around 1/5 to 1/4. I've heard that cavitation sets in around 6000 RPM or so, and I was above that for at least half the time.

Is there any good way to tell if the pump is spinning too fast? Right now I only have the stock gauge set - I'm planning to add aftermarket water temperature and oil temperature gauges, but can't afford a good set right now.

Do underdrive pulleys cause problems for daily driving? I'd like to keep my AC & PS, so I'd need one that supported those belts as well.

-=Russ=-
Syonyk is offline  
Old 11-01-04, 03:35 PM
  #2  
Senior Member
5 Year Member
 
Join Date: Feb 2004
Location: Raleigh, NC
Posts: 321
Likes: 0
Received 0 Likes on 0 Posts
Ultimately, your water temp is what matters - get a gauge. Autocross runs are so short, that even if you are cavitating for that 1 minute, you aren't going to damage the engine during that time. The Miata thermoswitch or fan mod might be a good idea to make sure the car will cool down afterward.

I am putting a Pettit underdrive pulley on my car (keeping the stock accessories: AC, PS, air pump, etc.), so I can let you know in a couple of weeks if it's a problem around town.
macdaddy is offline  
Old 11-01-04, 04:59 PM
  #3  
Rotary Freak
5 Year Member
Thread Starter
 
Join Date: Jun 2004
Location: Ames, IA
Posts: 2,718
Likes: 0
Received 0 Likes on 0 Posts
Neat. I'm getting a gauge... when I can afford one. :-/ It's an S4, so the stock gauge is actually halfway usable. Plus I still have the stock clutch fan (for now), so it cools down quickly.

-=Russ=-
Syonyk is offline  
Old 11-01-04, 05:14 PM
  #4  
Full Member
5 Year Member
 
Join Date: Feb 2004
Location: Toronto
Posts: 70
Likes: 0
Received 0 Likes on 0 Posts
A lesson learned the hard way

I have a 13B Bridgeport, that turn about 10,000rpm. After testing and running about 260 - 280 degrees water temp I finally called Mazdaspeed. They informed me that the stock pump and pulley cavitate above 6500RPM! With there new pulley system the problem was solved. HOWEVER, the Mazdaspeed pulley's do not work on the street where you are running about 2-3000rpm, the water pump turns to slowly. S o be careful what you do!
#84Racing is offline  
Old 11-01-04, 06:02 PM
  #5  
Rotary Freak
5 Year Member
Thread Starter
 
Join Date: Jun 2004
Location: Ames, IA
Posts: 2,718
Likes: 0
Received 0 Likes on 0 Posts
*nods* That's what I'm worried about - low pump speed on the street. That wouldn't be any good, to have it cool while racing but not while driving around town (it's still my daily driver).

I suppose the best solution would be an electric water pump, or at least an electrically driven water pump. A bit of a pain, though.

-=Russ=-
Syonyk is offline  
Old 11-01-04, 07:43 PM
  #6  
Lives on the Forum
10 Year Member
 
Join Date: Feb 2001
Location: n
Posts: 26,664
Likes: 0
Received 4 Likes on 4 Posts
You really need an aftermarket water temp gauge to monitor the water temps.
The stock water temp gauge is too inaccurate.


-Ted
RETed is offline  
Old 11-02-04, 02:14 PM
  #7  
Rotary Enthusiast
iTrader: (1)
 
Join Date: Jul 2004
Location: Rocket City, Alabama
Posts: 1,035
Likes: 0
Received 1 Like on 1 Post
I run the RB under drive pulley set on my 12A street port , street driven car, and I do not have any cooling problems at low rpms.

I do notice that when the headlights, taillights, wipers, and heater blower motor are all running, then I am a little lower in voltage at idle (the alt. is spinning a little slower too.)

I recommend those pulleys for all performance Mazda operations.
speedturn is offline  
Old 11-06-04, 02:51 PM
  #8  
10a *****
10 Year Member
 
Join Date: Jan 2004
Location: NZ
Posts: 306
Likes: 0
Received 0 Likes on 0 Posts
Running an engine without a thermostat - does that have any effect on possible cavitation (more water flow - less problems???)???

I have the very small race pully running from the shaft, but a standard water pump pully, and the motor runs a good temp even at extended periods around 10,000rpm (but does run to cold on the road - have a blocking card to stop air flow to a large part of the radiator).
re10 is offline  
Old 11-06-04, 03:43 PM
  #9  
No useless mods....
iTrader: (7)
 
Speed of light's Avatar
 
Join Date: Oct 2004
Location: San Diego
Posts: 1,182
Received 10 Likes on 6 Posts
I run the Pettit underdrive crank pulley [only] and it works fine for daily and street driving with all accessories.
Speed of light is offline  
Old 11-06-04, 10:43 PM
  #10  
Armchair engineer
iTrader: (2)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: http://www.k2rd.com
Posts: 24,578
Likes: 0
Received 123 Likes on 112 Posts
Originally Posted by RETed
You really need an aftermarket water temp gauge to monitor the water temps.
The stock water temp gauge is too inaccurate.


-Ted
we tested it vs the haltech and the greddy, the 84-88 water temp guage is very accurate.

c on the 84-85 guage is about 65c, half way is 91c, when the mechanical fan turns on.

h on both is 235F
j9fd3s is offline  
Old 11-08-04, 04:31 PM
  #11  
Rotary Enthusiast
iTrader: (1)
 
Join Date: Jul 2004
Location: Rocket City, Alabama
Posts: 1,035
Likes: 0
Received 1 Like on 1 Post
re10 - what year motor/ water pump housing are you using?
speedturn is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
SakeBomb Garage
Vendor Classifieds
6
08-09-18 05:54 PM
msilvia
3rd Generation Specific (1993-2002)
15
09-11-15 12:13 PM
SakeBomb Garage
Vendor Classifieds
1
09-07-15 03:44 PM


Thread Tools
Search this Thread
Quick Reply: How do you tell if your water pump is cavitating?


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: