Here was the setting. Car was in a garage with the door open. Outside temp was 95. I only let it idle from a cold start for 20 minutes. The stock temp gauge stayed in the middle, but the aftermarket one was reading about 230! The sensor is tapped into the thermostat housing. I have just replaced the thermostat with a new mazda one and did a 50/50 mix with a bottle of purple ice. I also have a koyo radiator. Coolant started to seep out of the AST cap and began leaking out of the plastic overflow as well! I shut it off. Also, the car has been running rough..just replaced the spark plugs and engine oil/filter as well. For some reason, the air pump is cycling on and off very often during idle. Here are the questions:

1. Is the car really running hot since the aftermarket gauge was 230 and the stock was normal and considering the above mentioned conditions?

2. I can't find a vacuum leak. Car is definately rich....i can hear little back fire poofs out the muffler on idle. Leaking injector? Why the lumpy and rough idle? I reset the ECU which seemed to help, but 20 minutes later after it was idling, i noticed the temp issue. Motor is 25k old built by rotary reliability and racing and was just checked out in april.

Trev

 

You never mentioned if the fans came on or not.

 

You know...they did...but it took awhile. After I shut the car off, I turned the ignition to the ON position and turned the AC to the low blower setting so the fans would come on.

Trev

 

something is wrong...I am in Dallas, TX lately temp is in 100*, at idle temp would never go past 85*...under normal load temp will go to 90*. Under hard driving temp increase to 92-95*C with AC on.

 

What about the coolant temp sensor....that could cause a rich condition as well as fail to turn the fans on at the correct temp, right?

Trev

 

Trev,
50/50 mix is the start of your problem, drain the radiator out(just the radiator) and refill with distilled water, this will give you 75% water/coolant mix. Next, replace your AST and cap as it seems you have a failing cap and thus isn't letting the system pressurize, which will control the temps much better than no pressure(in a water based system). The more coolant you add, think of Syrup, the thicker it is the more heat it will hold and won't allow heat to escape through the radiator. Remember it's a gradient. Good luck
Art

 

The stock ECU turns on the fans (on low speed) at 221F (105C) while the engine is on if you don't have any other accessories running. If you have the lights on, the defroster, vent at 3 or higher or any other major electrical load, then they willl come on at 208F (98C). If the A/C is on (any level), then the fans are always on. When idling, low speed should be plenty to drop your temps back down until the fans turn off again (around 200F). So, to check your guage, just idle the car until they turn on, check the gauge, it should read 221F.

 

i know a ton of guys using a 50/50 mix without any issues...maybe i am wrong though? Any other inputs?

Trev

 

I ran 50/50 for a long time with no issues. Though I have changed to a ratio closer to 70/30. But I don't think that's your problem.
I tend to think the running hot and bad idle are two seperate issues. As far as the idle, would a malfunctioning Airpump screw up your O2 sensor readings and make it run richer at idle? I don't know, just a thought.

 

well, i am getting a pulley kit to remove the air pump and i am also removing the EGR crap and bypassing the ast as well. I will see where that puts me.

Trev

 

Don't forget to buy a new pressure cap, even if you're going to remove the AST. I like the Stant 16psi cap , part number is 11242 .

-s-

 

Thanks....good idea.

Trev

 

anyone know what the recommended mazda thermostat temp is or even better the forum recommended thermostat temp?

 

...little update....been driving the car and car has stayed between the 180-200 mark, never higher than that. I had this friggin airpump...makes soooo much noise...i think i remember a mod to take care of it...

Trev

 

http://www.clubrx.org/default.asp?id...ntent=62&mnu=5
Would this help?