I have a 1994 auto with PFC and various mods: IC, exhaust, hi-flow cat, intake, DP, etc. I also have upgraded 2" Mazdatrix alum. radiator and radiator ducting. AST has been removed.

My car runs very cool (84-85 C) while cruising, but heats up pretty rapidly during idle or stop and go. Temps commonly rise to 100 C if I putter around too long and temps hit 110C one time idling!!!

I cannot figure out why because fans are both working, radiator is upgraded, ducting is in place and coolant system seems to be solid.

I have been told to wrap my DP, get dual Mocal oil coolers and install some upgraded fans, but this does not address the real issue: why are my temps so high. There are many other cars out there sporting as many mods with not even an upgraded radiator running better temps than mine.

Thanks.

 

normal for stock setup ... fans 1st on at 221F.

search:

fan switch mod
miata switch

for some, with cabin fan at 3 or more, or parking lights on, fans come on around 205F.

 

All coolant levels appear to be full (in AST, engine/rad, and overflow tank), yet the light/buzzer com on after hard driving after the car has been shut off and is sitting cooling with the key in the "on" position (motor off) so the fans will run. WHen I start the car, the light and buzzer stay on. this has happened twice in a 3 day period. Any idea what the problem might be?

 

This happened to me the other day. Once I turned the car on the temps went way up and the buzzer came on. This was after the car was idling for way too long.

Even after letting it sit, the heat was enough that when I restarted it the buzzer came on because the radiator needs time to work. The buzzer is being driven by the temperature being registered until some cooling takes place.

 

Not true. The buzzer is low coolant in the filler neck. Since you have no AST you have to wait till it cools and add coolant to fully burp the system, may take some time. If you have a small leak somewhere, could take forever. IMHO

 

May want to check the thermostat as well.

Are you sure the fan is on full speed when it's hot? It has 3 speeds I think.