i have a 1987 mazda RX7 GXL i have replaced everything i can think of in the cooling system but yet it still running hot. first i was told to run full antifreezde(not 50/50) then i replaced my thermostat (twice the first one was defected) then i placed my radiater and water pump. replaced the water pump belt. I was told the "heater core" wouln't cause the RX7's to run hot (i was told by a mazda rotary specialest). i can't figure this problem out for anything. please help

 

what thermostat are you using?

Non OEM thermostats tend to run warm. You want to make sure you are using only the OEM thermostat or the car will run warm (among other issues). DO NOT use the STANT brand thermostat. It has been shown to have issues on S4 models.

And 100% coolant will also result in the engine running warm. You want to use 50/50 or 60/40 (water/coolant) for better heat exchange. You can go as high as 70/30 (water/coolant) but that requires more frequent coolant changes (at least once a year, as the anti corrosion chemicals in the coolant will break down too fast). Water wetter or a similar product is recommended when using less than 40% coolant. Make sure you are only using distilled water (available at most grocery stores) as your water in the mix, as tap water often contains harmful silicates and phosphors that will increase build up in the cooling system.

Using 100% coolant will not cool very well. Any mechanic that told you to do this, does not have a clue and should not be allowed near your car.

If they same clueless bob told you to change the heater core, you should doubly stay away from him or her, as the heater core doesn't even come into play until you crank/turn on your in car heat, with the Logicon.

 

thanx alot! i'll fix my coolant to 50/50. any other ideas would still be appreciated

 

well again... what brand thermostat are you using?

 

u were correct. i had bought my thermostat from autozone. i pulled it out this morning and it ran fine for a lil bit but on longer trips of caurse it ran hot. question though. is it normal for my brakes to go crazy when my car runs hot? i couldn't get my brake pedal to go down for nothing,i tried everything to push it down and it just wouldn't budge,all my braking components are brand new. i've replaced everything in the braking system. plz help....

 

YOu need to use the correct thermostat... you can't just pull it out and run without it ; you will have issues.

 

price checked the thermostat from mazda,its like $25 after tax,i so don't have any money. im not currently driving it,i won't drive it knowing it can run hot,na,i'll just wait it out,lol.