Gauge temp --> 1/3, 1/2, 1/3... need your advice.
 

Ok here's the deal: when I drive really moderatly my 86 GXL, the gauge temp stays at 1/3; but when I redline it or cruise around 4000 rpm, I see it rises to almost the half of its scale.

I know the normal temp of the S4 is 1/3 of the scale, and I also know that it is quite normal for an engine to rise its temp when driven spirited. Just want to know what ½ of the gauge means on the FCs.

And while I'm here, my idle is quite rough and there are some backfires; but the car runs really great when I drive it. I know the idles tend to be rough on rotaries, but what do you think it means?

Thanks a lot guys.

I'd flush the rad, and change the T-stat.. seems like maybe the T-stat is sticking closed.

I have the same problem with my S4 1986 GXL. Only when i rev the engine at 4K RPM or more my temp gauge is showing 1/2 of the scale.
At idle or at low engine rev the gauge is showing 1/3 of the scale.
How hot is 1/2 of the scale temp ????
S4 TII are showing 1/2 of the scale at normal temp ????

1/4 on the scale is normal operating temp for S4's. S5's half way is normal operating temp. I dont know the exact temp but I do know that you need to shut down if your temp reads 1/2 on an S4. I would flush the coolant and change out the t-stat. Make sure you bleed the system when you are done. Also make sure you have the plastic undertray on your car as that helps route air to the rad.

I found this from aaroncake at http://www.aaroncake.net/RX-7/buy1.htm

''Overheating is instant death for a rotary engine and is not tolerated even once. For '86-88 cars, normal operating temperature is about 1/4 way up the gauge. For '89-91 cars it is about half way. Both gauges will be very slightly higher if the A/C is on.''

STOP LOOKING AT THE STOCK GAUGE.
If you want ACCURATE temps / numbers, get a REAL coolant temp gauge.
Bad engine grounds will cause the stock water temp gauge to read "wrong".


-Ted

+1

So I'll change the coolant, the T-stat (it's pretty cheap if I remember well), and take a look at an aftermarket gauge temp (I have an aftermarket oil pressure gauge and it is way more accurate than the stock one was).

But I thought that if it was the T-stat, the temperature would not go back to normal after a while??? And it does come back.

Anyway, thanks.

Where can you get a OEM thermostat? Apparently Mazdatrix is going with an non-OEM one now.

All the ones I have gotten from M-Trix are OEM.

:dunno:

mine stays just below the 1/2 mark, my aftermarket temp gauge reads about 210-240. It also depends on how hot it is outside of where its gonna be on the gauges.

No problems to get a OEM thermostat here in Canada from a Mazda Dealer. I just order one today.
Thermostat OEM Part # 8AF1-15-171, Thermostat Gasket OEM Part #1757-15-173A.

Yep, I just picked one up from the dealer yesterday.

When the stock gauge is at 1/2 way you are running 210-240 degrees ?? That is very bad.

Ive run my car to 1/2 way before and had it over heat on me a couple times but not badly, ive been told 1/2 way is not bad and 3/4 is where you worry, on s4. It overheated because of a bad clutch fan :(

On highway crusing at 85mph fifth gear, temp will come back down if it goes up and usually is running from 178-188 , i believe my tstat is set for 195.

In the past it seems like my car usually just ran 180 and the temp never budged, can hotter weather cause the engine to run hotter temps even on the highway ?

#1...flush out the coolent
#2...the ups and downs in temperature can be caused by air pockets in the coolent line, make sure you fill it all the way full when you refill it
#3...replace the thermostat, it is cheap
#4...build a radiator cooling panel for the top and bottom

#5??...if you dont mind the way it looks you can space out the hood hinges. this will make a 1 inch gap in front of the windshield for heat to rise out of. it does help but some people will flame you for it.

According to the owner's manual, anything in the boxed area is normal. Whether or not I believe that... :p:

I wouldn't say 1/2 way is bad, assuming the gauge is working correctly (refer to Ted's post).

Here's a pic of mine fwiw.

https://www.rx7club.com/attachment.p...hmentid=228871

http://www.rx7.com/store/rx7/fcengine_cooling.html

if you dont want to pay mazda dealer prices on the oem theromstat. rx7.com is the only other place i know of.

so my voltmeter IS correct... everyone has been telling me that if my voltmeter should read 14.4 volts or something.

It should. Mine doesn't but it's never caused a problem. :dunno:

from my experience.

1/4 andunder is 180 or lower
1/4-1/3 can be anywhere between 180-195
1/3-1/2 around 195-210
1/2-3/4 around 205-235+

cars voltage shloud normally be at 14.4, thats healthy. you dont need to have it. my cars voltage is 12 when on or off :mad: ...

it makes me mad, cus if you even think of putting in a sound system two things will happen.
1. your car wont be able to handle the sudden drops in voltage
2. you wont get the rated watts, well you wont anyways cus most companies test at 17volts or even 15volts.

Don't mean to threadjack, but how do you overcome the fact that the car's stock electrical system isn't strong enough to run a real sound system?

I have a pair of subs and an amp. Frequently, when I turn up the bass, the system shuts off and restarts.

More powerful alternator. The stock S4 one is only rated at 70 amps. That's not a hell of a lot.

Good thing I kept reading b4 I said that I would of said the same thing