AFTER taking out the Autozone thermostat that I put in yesterday, I looked in the "bunghole" lol and found the temp stamped 195F... exactly what I DIDN'T ASK FOR.

So maybe it wasn't the thermostat that failed this time. It was the 'tard behind the counter. And me too for not checking.

BTW, replaced with OEM one today, all good!

 

I only use OEM thermostats because of hit and miss quality issues with aftermarket brands. Some have had good luck with other brands, but it's not worth it to me since OEM is comparable in cost. I stocked up and bought 10 thermostats about 5 years ago so I wouldn't have to buy any for a long long time. I'm sure OEM is made buy different brands to, but Mazda also has quality requirements they have to comply with. I never had problems with an OEM brand.

As for the dolt salesman, yes they are out there. I ran into one trying to buy fuel injection hose where he said carburater hose was the same. But there are some very knowledgeable ones out there to.

 

Actually, this particular OEM one has a MOTORAD stamp on it. I looked for a part number to share with you guys, but no such luck.

In other news... my RTEK 2.1 is 100% up and running, as well as my crappy manual boost controller I got in the mail today. Its the ball and spring, ebay, 20 dollar special. I reached my goal of 10 psi! No more till I get a better intercooler.

 

I just replaced mine today too mine had a Stant thermo in it's place, good god no wonder mine was wanting to overheat so badly. That thing was nothing like the oem one. I took pics I'll post tomorrow. Except I ran into the problem of my bolts shearing off in the neck so after we took it off, we had to get them out. I'll go into detail in my build thread about the easiest way to get sheared/broken bolts out of their respective taps. But now I just have find replancement bolts to use. Grr.

 

I was told my t2 project was overheating from who i bought ut off,ive not run it yet because im missing a few parts but it has a stant radiator cap and tstat (I saw the tstat box in the car when cleaning after I bought it.)

I'm hoping the overheating was due to using this garbage, I only use OEM Mazda tstat and radiator caps.

If it was only that I would be sooo happy, saves me from getting a rebuild due to blown coolant seals.

Rotary >Pistons

 

For the last few years all the OEM thermostats I have ordered have come in as STANT which is an aftermarket brand. These are bought from various mazda suppliers including ray at malloy mazda. Apparently the factory has ceased offering the original thermostat, at least for 89-95 models. The STANT version does not have the pinhole or jiggle pin.

 

Just out of Curiosity Kevin..
The main reason I don't get them is because of that Jiggle pin being missing,But would a Stant be ok if say a 1/8(or so) hole was placed where the jiggle pin location should be?

 

The OEM FD thermostat is a direct replacement for the S5's, jiggle pin and o-ring seal are identical.

 

Can someone explain me why its so recommended to use a OEM Mazda thermostat ? Well I do, but not everyone I know who drives an FC does so. Whats the difference with these and aftermarket ones ?

I even testet mine before installing to make sure it works.


Thanks

 

my cars all have drilled Stants in them, yet to have an issue.

 

If it wasn't drilled you probably would though

Rotary >Pistons

 

I have 2 engines for my bike the one had ,it looks like the correct with jiggle pin and the other had no hole or pin so I drilled a small hole same place as one with pin and put a small aluminum cotter pin in the hole cut it off short and spread it enough just to keep it in place . The one with the cotter pin worked good all last summer , not that many hours mind you . I'm probably wrong but I think the pin helps collect the air and let it through where as just a hole might not let the air through as well . I realize you guys know but some of the members don't realize that the pin goes to the top side when installed .

 

See post #1.

Going to a parts store, just know that what you ask for in the computer may not be what you get... even if the box has the right part number. Something in the inventory is screwed up.

I asked for a 180F thermostat, I got a 195F thermostat. The problem was that the computer called that part number a 180F one... they are reversed.

I ended up just getting one from Mazda.

 

Why would someone want a 195 tstat?

Rotary >Pistons

 

Thanks,
so thats the fuss around oem ones. I got mine too from the mazda stealer, its a 180F one (82° Celsius). And I installed it with the small jiggle pin on top. It was in a sealed mazda pack, with the gasket in a sealed mazda "Genuine mazda parts" bag. It even says 82° on the thermostat, its engraved on it. I just felt I should use a true OEM one for this task, specially about the rumors spreading. I don't want to risk a 10 grand engine for a 20 dollar thermostat ...

I often had the discussion with a friend about that, his FC was overheating like crazy and there was no thermostat in it. Temp needle peaked that is. I thought that motor is going to pop every second ... I just stopped discussing that matter as its no use. I just pretend it never happened.


Here is a pic of my refurbished waterpump housing and the thermostat before assembly:

 

I thought the tstat can only fit one way?

Also shouldn't running no tstat make it run cooler

Rotary >Pistons

 

No, because the water wont stay in the radiator long enough to cool down... in theory anyway.

The thermostat is in this case a regulating valve... open % is a function of temperature.

 

Where I live it's not uncommon to get to -30 today with the wind chill it's -41 and by the time the water circulates through the heating unit it drops considerable . It use to be common to change to 195 in the winter and then back in spring , heck there use to be a 205 but would not be very kind to the little rx7 engines , for large cast iron engines 195 is acceptable in winter but the modern engine can't take the extra very well and have a much better system than the old .

 

A theory backed by zero empirical testing, and one that is completely false. Greater coolant flow always causes greater cooling capacity.
Decreasing coolant flow may allow the coolant to stay in the rad longer, but it also makes the coolant stay in the block longer.

 

Bravo.
I'm always amused when someone claims the water spends more/less time in the rad and ignores the corollary, it also spends more/less time in the engine.

 

It appears we no longer have a choice unless you wish to reuse an old original tstat.

I have just been installing the stants as is and have had no major issues, but I still don't "like" it.

 

Newer vehicles are designed to run hotter for better MPG and emissions requirements. In general the hotter you run an internal combustion engine, the more efficiently it burns the fuel charge. The downside is that a hotter long term average temp shortens the life of cooling components and in some cases the engine itself.

Mazda experimented with this on the FD models by installing an electric fan cut-on switch that is rated for about 226F. Yes, that's right, they wanted the engine to consistently run that hot before the cooling fans would come on during low speed driving.

 

Years ago I bought a 91 turbo rx7. You could drive it around town fine, and the temp would never fully come up. If you stayed at high rpm long enough, say on the interstate running 80, the temps would come up and in fact begin to rise out of control and eventually you would have to slow down or pull over and let it cool off.

Come to find out someone had "gutted" the thermostat, leaving only the sealing ring and thermostat body in place to form a seal between the neck and housing, but cut off the tstat valve. This let the water pump push the coolant through the radiator too rapidly, it went right back into the block before having adequate time for heat exchange to occur, and over a period of several minutes of this high rpm operation the system was unable to remove as much heat as the block created.

Once a new thermostat was installed the car drove perfectly and had no further temperature issues whatsoever.

True this was just one example, but it was proof enough to suit me.

 

The water pump housing has a bypass hole, an inch or less in diameter, directly below the thermostat in its casting to allow the coolant to circulate when the thermostat is closed. This prevents the combustion chamber side of the engine from overheating when the thermostat is closed.
When the thermostat opens, the plunger moves downward and plugs this hole, forcing the water to circulate through the radiator. This is the purpose of the large metal disk at the bottom of the thermostat.

With a gutted thermostat, the coolant will choose the path of least resistance, and rather than flow through the radiator, will recirculate through the bypass.
When the engine is operating at high load with this bypass open, the engine can overheat. \this is likely what occurred in your example.

When running a gutted thermostat, the proper technique is to hammer a freeze plug into this bypass, or tap and thread in a pipe plug.

Reference #6 from Racing Beat.
Rotary Tech Tips: Water Cooling

 

Some powdercoater did a no-no there. The proper way to powdercoat is to mask off all mating surfaces and plug any threaded holes. Now you risk difficulty installing screws and sensors, getting proper ground through the part required for the alternator (and sometimes sensors) to work properly, and perhaps difficulty sealing mating surfaces.