I dont know if this is happening to some of you or not, but some times when im driving around with my totally stock 93 FD and stop and turn off my car.....

after a few seconds i start hearing water boiling under the hood, but its a light boiling not really strong, which is not making the Water going out at all.....

is this normal or does it indicate something???

 

That's the coolant locally boiling at the hot spots in the engine once the coolant is not moving after shut-down. In the stock FD, this is normal, especially with the 13-psi AST cap which was put on in one of the recalls. However, many people use a variety of methods (FC thermoswitch, fan mods, etc.) to lower coolant temperatures to prevent this.

 

Thanks Man for the answer...

What year of the FC is that thermostat??

 

What temps are u seeing in Saudi?

I don't think Mazda tested the cars there in the heat.

Did u have the radiator upgraded?

 

check ur radiator cap too

 

The item is the THERMOSWITCH that turns on the fans. IIRC, the FC (2nd gen RX7) does it at ~205F vs ~221F for the FD version.

 

I don't think it is 'normal', I think this indicates that you are getting air into your system.

I was getting these noises until I replaced the caps.

 

Before I did the Miata thermoswitch, I had mild "boiling" noises whenever I parked the car after driving more than 15 minutes in hot weather. There was no air in my cooling system. Since I did the Miata (same as FC, but different electrical connector) thermoswitch, it no longer does it.

 

i have the boiling sounds too
hopefully mine is normal...

 

Are you also seeing any white smoke coming out of your exhaust at start-up? I had that water rushing sound after shut off when my car's coolant seals went bad due to over heating- necessitating a rebuild. I hope that this isn't the case for you.

 

oh man...thats exactly whats happening with me
bit of white smoke at start up and a bit of water rushing sounds after turn off

 

Game over.

 

Which is better? How do you perform this mod?

 

Don't get alarmed unless you are losing coolant. "A bit of white smoke" at startup could just be your engine burning off condensation that accumulated overnight, and the "water rushing sounds" could be caused by the aforementioned localized boiling.

 

My FD lets off a little white smoke on cold mornings after start up. I figure it's mostly water vapor or something because my coolant never goes down and the car runs fine.

I only had the boiling sound once... I was racing the car at a track and I went off track and got stuck. I didn't know if I had damaged my car or not so I shut it off. I could definately hear mild boiling. Normally I'd wait several minutes before shutting off after driving the car hard.

 

I've heard that sound before myself but in my situation, it was because the reservoir was low which left some air pockets in the engine. After topping the system up with coolant and bleeding the air out of the system, it went away. No more boiling noises.

 

i just did this on sat, i took the car out for a drive about 20 min of light drivng around 60 mph and oh yea i added disstilled water to it before i left becuase im on 122,789 OEM miles, so i get back home and i was taking something out of the trunk and then there it happend i heard this strong rush of gurggling sound, and then i open the trunk and it was my coolant over flow tank spillin over like it had to much to drink on a friday night, so i let it be and it went away, i wonder if i put to much water in the system. let me know if you guys have done thins

 

lets hope thats the case
my cars been running fine and theres no coolant loss
and the white smoke only happens after i garage the car for over 3 days straight.
but thanks for the info.
leaves me at peace for a bit...

 

you are gangster my friend!

 

HOLD ON GUYS! That sound is perfectly normal for a stock setup. Upon hard operation or prolonged slow operation at high temperatures, some water bubbles over into the AST after the engine is shut down. Sounds like a coffee pot percolating. I've been driving my FD going on two years now. No deteriortation in power, performance or anything else. Your suggestion on the FC thermoswitch is something I haven't tried yet. If it reduces water temps that much, I say go for it.

 

i have a koyo rad and aftermarket ast and mine boils on a hot day

 

i like cabbage

 

The FC thermoswitch is better because its connector is the same as the FD's, so it's easier to install than the Miata one that doesn't match the FD connector. Otherwise, their function is the same.

 

happens to me after a spirit drive

 

OK. The FC thermoswitch it is..... Now.... Should I go to the Parts department at Mazda and ask for it by name?..... How much is it and where is this installed?