I have a 94 junkyard motor and brand new radiator I put in. It wasn't warming up, so I got a new thermostat under warranty. Symptoms haven't changed.

According to obd2, the car does like it should when still - heats to around 200, then the thermostat opens, drops to 192, and then starts rising again.

When I drive, though, depending on how cold it is outside, temps are more like 150-176f. Air temp between 20 and 50f.

Any ideas? Is this normal? I burped the radiator a second time to be sure there wasn't trapped air, I got nothing out.

 

Good discussion here:
My experiences with thermostats - Spec Miata Garage - Mazda Racers

 

The small hole which allows water to pass through the closed thermostat is too big.

How well does your heater work?

 

I have been having similar problems with my 2001. I replaced the thermostat and radiator cap and now it takes forever to warm up and my heater it terrible and only works after a loooong time of the stock temperature gauge being "normal." The thermostat I used was the one that came in FM's kit, so it was probably the OEM Mazda one. From EricJ's link, it seems I should get that generic 180 degree thermostat from NAPA?

 

Did you install the thermostat correctly? Putting it on backwards will alow the waterpump to compress the spring and allow water to flow through.

 

I really do not know. I will have to take it off and see, but what is the correct orientation?

 

in the proper orientation, the wax filled cylinder surrounded by a spring is installed toward the engine.

 

Mine was clocked a few degrees off from pointing straight at the engine and my car took a good 20 minutes of driving to reach temperature. I finally went and installed it correctly last week and I can't believe what a difference it made. Car heats up in just a couple minutes now.

 

Btmiata what do you mean a few degrees off?

Mine is installed in the correct direction with the jiggle pin at the top.

 

I mean a few degrees off rotation. My jiggle pin was slightly to the left so I had to rotate the t-stat a few degrees to the right(so it ended up pointing straight).

 

few degrees off on the jiggle pin wont make a difference. I have the feeling the entire thermostat was crooked and there was a giant gap somewhere. You can install it any rotation, as long as its flush that extra 20 or even 180 degrees (jiggle pin on the bottom) wont make a difference vs the pressures the cooling system sees.

 

Well I checked it again and it looked perfect, so I swapped the Mazda one I had (and had already replaced once under warranty assuming it had gone bad) with a cheapo stant superstat... Did the trick, now doing an even 190.4 on the highway. No idea, but I'm happy it's fixed.

Kept the Mazda one in case it gets too warm this summer or something.

Thanks for the help everyone.

 

surprised you had issues with the oem dual thermostat.

 

What can I say. Thought the one I had just went bad, returned it and got another under warranty, same exact issue. Put on a stant, no problems at all. Can't be my installation procedure or this AZ one wouldn't work correctly. I'm going to stick with the cheaper thermostats in the future, myself.

 

Maybe you got lucky this time around?