Hey friends, my '86 n/a has been overheating the past couple days (coincidentally with very hot weather)..anyways, i checked the upper and lower rad. hoses and no tears or leaks coming from there. there was smoke coming from the radiator cap. i replaced the cap today and no more smoke exiting the cap area or leakage to be seen but engine still getting extremely hot and once shut off, hot boiling water/coolant can be heard from both the coolant reservoir tank and the engine itself...



some culprits i've heard are bad thermostat or possibly a bad water pump...could it be the radiator itself acting up? anyone been in my shoes? thanks..

Replace the thermostat with a genuine Mazda thermostat. Check if a little bit of coolant is dripping(or pissing) under the water pump shaft. This is the location of the weep hole. If it is leaking, the bearing is shot and the water pump needs to be replaced. I'd flush the radiator and replace the coolant. Also something to keep in mind, check the oil system. It handles a fair share the cooling too. Make sure the oil cooler is working properly and there is decent oil pressure. Where is the needle on the temp gauge or how hot do you think it is running at?

Thanks for the quick reply..I plan on getting a Mazda thermostat first thing tomorrow. I will also check under the water pump shaft for leaking. Normal operation used to show the needle at about 33-40% between cold and hot. Its getting to 80-90% hot now.

9 out 10 it is the thermostat... i have only seen a few raditors go out

I had a water pump go on me once in my FC, you'll know almost immediately if it's the water pump. Carr went from normal op. temps to pegged in less than a minute or two.



Steve

When mine did this it was just a dead ass motor

When my motor had a bad coolant seal, the car seemed to run fine, a little hot but never too bad, untill I shut it off. Then it would puke a bunch of coolant out of the overflow all over the driveway.

just change everything- the parts are cheap