What thermostat is everyone running? Where can I get a reliable, quality OEM thermostat from? I've searched but everyone has had problems with the stant which is apparently what Mazda and Mazdatrix sells. I'd prefer to buy one locally so I don't have to wait. The Autozone one seems to have good reviews.

 

Napa.

 

autozone sells a failsafe brand, if the thermostat fails it's designed to fail in the open position. I have not used it yet nor know it's operation but when the time comes for me i'll probably get the failsafe. I think it's closer to $20 bucks tho, actually I'm not even sure if they make it for our application, but i'd check if I were you.

 

I think a lot of people want the OEM one with the jiggle pin, but Mazda isn't even selling it anymore?

 

My local dealer still has the OEM thermostat with the jiggle pin, so that's what I use.

When those run out I'll probably still buy them from the dealer, but drill a little hole in place of the pin before installation.

 

i run the car without a thermostat.
in one summer i went thru 2, both of them failed, and ended up closed.
so no more problems ever since i did this

 

No more problems except higher engine wear, lower mileage, and the risk of overheating (assuming you didn't plug the bypass).

 

Mazdatrix doesn't sell oem's?? I ordered a mazda oem one through them last spring...

 

lower mileage ???... what do you mean.
and it stopped the overheating problem when i removed it.
it never went higer then 1/3 on a hot day. otherwise it was stable at 1/4. and which bypass are you talking about !??

 

Thats what I read, one guy tried like 3 Mazda tstats and all failed. Anyway I followed clokker's suggestion and went to NAPA. The thermostat (ordered an FD one as he suggested-the listed one for the FC is too big) is made by Tama enterprises from Japan and it has the jiggle pin and comes with the O ring. Opens at 180*F. Pics are next to my old one with no jiggle pin which worked without problems for ~60k miles and 3 years:

 

My local Mazda dealer still has them as of about 6 months ago. Eww look at that dirty keyboard.

 

the problem is with running sans tstat, you dont actually know the engines temp. sure the water temp is cooler but thats because its not able to stay in the block and do its job of absorbing heat. which means the heat is staying inside the engine, making it run hotter and killing lifespan. your temp gauge isnt there to measure water temps, its there to measure engine temps. its no longer accurate if there is no gate to monitor the flow of the water.

 

This shows clear lack of understanding of basic thermodynamic principles. While running a t-stat in these cars is clearly a better option than removing and not replacing it, it is certainly not for the reason(s) stated above.

 

what reasons then?

 

OP, why the rusty Tstat? Not using proper a/f coolant mix?

 

1. The engine does not operate at it's design temperature, in many cases not even close to it. This increases wear to varying degrees depending on the oil used. Primarily due to all the tolerances being not at design. The engine was designed to operate at a specific temperature and all the pieces, seals, etc are designed to operate at that temp. At lower temps (and higher temps) in simple terms the parts don't fit and work together properly, increased wear is the result. It is even worse if you are running a heavy oil (marginally so).

2. The pump and cooling system was designed to have the thermostat in its housing. The primary and bypass system was not designed to freeflow without it. Thus there is no control over where the water goes. This can POTENTIALLY under certain circumstances actually starve the engine coolant passages of minimum proper coolant GPM while at operating temp. (gallons per minute or volumetric flow).

Supplemental:

Measuring coolant temp is not ever actually measuring engine temperature, thermostat or no thermostat. It is just the generally accepted method of monitoring engine temperature. Assuming a full cooling system (no air) you can still reasonable expect that your coolant temp sensor is reading properly (except if it is the stock piece of crap). This is also assuming that the sensor is in the proper location. Further, in rotary engines the oil temp is the more important parallel indicator of engine temperature.

 

Not sure, maybe the previous owner didn't. It has been in there for probably 4-5 years if you count the previous owner's use, probably even longer so I'm sure its bound to catch some rust. I just ran the car and it feels great!

 

Further to rocklobster's reply- as stated, if you run no T-stat, your engine likely runs below operating temperature most of the time. Which in a fuel injected car, in turn means the ECU will keep it running richer, already an issue in our cars, hurting mileage and increasing wear with carbon buildup and raw gas thinning the lube within the trochoid chamber.

When my wife's Saturn's cylinder head temp sensor failed a couple winters back, the mileage went down noticeably, you could smell fuel in the exhaust (a-la RX-7!), and the oil smelled of gasoline and got visibly dirty quickly. It also took a lot longer to warm up, because of the ECU kept it running rich, even when the dash gauge showed it was up to operating temp (runs off a different sensor), because the ECU was seeing a cold engine.

 

And as another bonus when your car runs rich it destroys your cat converter (assuming you have one)! Which in turn causes more engine wear and heat!

http://en.wikipedia.org/wiki/Cascade_failure