i just replaced my old thermostat with a 180 degree one...the car was overheating and it basically just was undriveable (i need it as my daily driver) so i got the 180 thermostat and replaced it...anyways now my car will only go up to 1/4 up the stock gauge. im assuming thats right around 180 but is that too low. from what i have heard in the past its not good to run a car too cold....it used to cruise around 1/2 way up the gauge. now even driving "spirited" it only goes to 1/4....probably nothing to worry about right? should i go buy a higher one. its easy enough to reaplace...

 

First - the dash gauge is not linear.
It's more of a hot/cold pointer.

On many RX-7's 1/4 scale is normal.

If you need to know the real coolant temp, you will need to install a mechanical temp gauge.

It sounds like you replaced a bad stat with a good one.
You're good to go..

 

The thermostat is supposed to be 180degF (and should only be from Mazda) and on the S4 temp gauge 1/4 is the normal operating temp. Congrats, you have fixed your broken car.

 

Something to look at next time.

Just below the stat seat, inside the pump housing is a bypass hole.
The stat is supposed to have a spring loaded disc that covers that hole.
If you old stat didn't have that extra valve disc about 1/3 of your coolant never saw the radiator.

 

FSM Spec:

Thermostat will open anywhere between 180 and 194, with full lift at around 204.

Now my question for the thread starter. What kind of thermostat did you purchase?

 

its a Stant 180 degree.

and yes the car seems a lot happier now. the old thermostat did not cover that hole at all. it barely moved. not good....i felt really dumb because i had been cruising around halfway for a while then it went to 3/4's and i stopped driving...

 

Just to reinforce what everyone is saying, my car normally operates between 185-200 under normal (load) conditions, dropping down to 180 when I'm coasting on the highway or something. This equals 1/4" on the stock guage.

 

I was afraid you were going to say that. You should consider replacing that thermostat with a Mazda T-Stat. But dont take my word on it, do a search.

 

whats the issue with Stant's?

 

oh jeez...i remember hearing something about stant....so i guess it is bad. they arent expensive so maybe ill head to the dealership and get OEM....

 

Mazda thermostats used to be good but the ones I have bought in the last few years don't look any different from Stant's.

 

My guage reads half way up sometimes(it's an S4) especially on long highway drives uphill and stuff. That bad?

 

No.. especially in hot weather.. You got your uinderbelly pan and top shrouds in front of the rad on right??

 

my 88 se runs just under 1/2 all the time, with a new mazda oem stat. All shrouds still in place, flushed and refilled with 50/50 coolant mix. I believe a lower coolant/water ratio should give your system better cooling capacity, but I havent tried it yet.

 

yeah...i have like 90/10....very little coolant. water transfers heat better. i just keep the coolant in there because it has chemicals to keep my radiator from deteriorating...a little tip my friends grandfather gave me.

 

anything less than 30 percent coolant, and there are not enough chemicals in the coolant to prevent corrosion.

You are wrecking your motor running at only 10 percent coolant

 

well i cant really say its 90/10 but its not a lot....its got a light green tint. when i replaced my thermostat i only put water back in after so whatever stayed in the system while i had it unhooked is still coolant....probably more than 10%...just a little exageration. ill probably drain the whole thing this weekend because i wanna do a complete fluid flush. time for a real tuneup. plugs, wires, hoses, fluids, everything. my car will like me a lot better then.

 

Where did you get that? The FSM's I have say the thermostat should start to open at 177-182degF (hence the "180" rating) and be fully open at 203degF.

Why would you run that much coolant? A 35% mix will protect you from freezing down to 3degF, provide suffucient corrosion protection and provide better cooling.

 

I am running a 160 thermostat in my S4 motor that is in my GSL-SE.
Car has no emissions what so ever, TB mod, full RB streetport exhaust, small port, and my guage never leaves 1/4 even under hard driving or running 120.
I also had my rad. dipped, cleaned, and painted. Looks new and flows nice.

As of now I have no under belly pan (too lazy to put it back on) and no fan shroud as i am swapping over to a e-fan.