I just bought an 87 na RX-7. She runs like a champ. But lately it will overheat on the gauge. So i check the engine and it feels cold. The overheating is quick too, from when I start it up after a 2 or more hour sit, the car will overheat in less than a minute with full coolant and I just replaced the thermostat. So, while i was changing the t-stat, I noticed a 1/2 wide (probly smaller?) hole in the water neck or t-stat cover. I looked into it and there is supposed to be a thermoswitch or something senser majig. Would this sensor cause this problem? The hole has no threads in it to screw in a sensor, but the "Chiltons manual" (wuppee) says there is this thermoswitch, and i have a loose wire plug in the area. any ideas? thx
JR

 

Sorry, i dont know why I wrote 87, its an 88 R. sorry

 

i would be willing to bet your stock water gauge is wrong from the information you've described..

as i research and learn more and more about the FCs, it would seem that electrical malfunctions are very common and easily curable.. alot of problems people have or THINK they have are usually due to a bad ground somewhere, something not getting the proper voltage to operate properly, or even a gauge in the cluster putting out the wrong reading..

 

On your car that hole does not have anything in it in and that loose green wire with a connector should not have anything plugged into it. It will overheat quite quickly if your fan clutch is bad. Temporarily (or permanently) install a new sensor in the block and an aftermarket gauge. The sensor is on the drivers side of the engine right next to the oil pressure sensor below and left of the oil filter. I picked up a cheap electric guage at pep boys for $13 and made sure it was reasonably accurate by testing it in boiling water with a 12volt battery and some aligator clips to get it power and ground it. It was right on the money.