ive been wondering a while why my fd keeps overheating during idle.
it does fine on the highway since theres constant airflow to the engine, havent gotten any aftermarket qauges, but all i know is that my stock temp gauge gets pretty close to Hot. so i just let the engine sit and cool off, but then again i cant keep doing that forever. anyone has suggestions of what can be wrong? and my fans dont kick in until it gets real hot, maybe a new thermostat? i have a RE intake, greddy smic, and a smaller battery, havent put in the dp yet but i know that wouldnt really affect engine temps.
any help would be useful
thanks

 

could be the thermostat

also what is your coolant mixture like?

i say get a aftermarket gauge asap, they are cheap and easy to install..this could save you thousands..

do the cheap fan mod, remove the a/c relay thats located in the bay and turn on the a/c and have your fans on during city driving..

 

yeah im probly gonna go with the fc thermostat or something
and my coolant mixture is 50/50
gauges coming soon but when you take off the ac relay, its basically thinking the cars on with ac so the fan kicks in correct?

 

Do you mean FC thermoSWITCH?

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/its-official-do-not-buy-miata-thermoswitch-until-you-read-397156/

-s-

 

Check whether your fans are working properly. An FD sitting at idle will overheat if the fans are not working in proper cycle. (workshop manual 94, cooling E-11 shows the testing method for the fans)

Also you should try a 70/30 coolant water mixture.

 

I think the term "overheating" is not being used properly a lot on this forum. What do you mean? Does it boil? If not, there is really no problem. Engines are supposed to operate "as hot as possible, without boiling". My car will run at idle (once warmed up) around 95 if I let it idle a lot. On the road it typically runs around 83-85, 93 on hot days. 85 on hot days on the highway. If I shut it down for 5 min. on hot days it's at 105-109 when I restart it, but it quickly returns to 93-95. All temps C of course, and noted from the PFC commander. I use 50/50 coolant mix.

 

when im talking about overheating, im not talking about slight overheat. when the engine is off, you can hear coolant boiling. in any car coolant should not be boiling. i need to test out my fans first before anything, then probably get the fc thermoswitch, ive got a koyo radiator to be installed soon but i know that wouldnt help a lot in terms of cooling at idle. 50/50 mixture for summer is good?

 

50/50 for cold temps is good... you should be thinning it out to between 70/30 - 80/20 in the summer. You might want to rethink the "no car should ever boil coolant" theory though... search around and find that many members on the forum run 100-110 C at the track. When I'm stuck in traffic jams on the highway for 10 or 15 minutes, my temps will top off around 100-102 with no problems.

However, what worries me though and no one seems to have mentioned it yet is how the stock gauge is reading close to hot. It takes A LOT of heat to break it out of the middle range since it's not linear. I've run up to 107 C before and the needle hasn't budged over the halfway point. IF your sensor and gauge are working correctly, then there is definitely a problem, but I would check those first.