Please tell me why my car runs so hot!!
 

Background: 34k mile pristine FD. Only mods are Koyo Radiator and DP. I guess the old owner didn't take good care of it, or the engine didn't like being driven so few miles, because it ate an apex seal. I had the motor rebuilt with a mild street port. Now the temps are getting up into the upper 90's here in FL, and if I run the AC, my car runs SUPER hot, like 145ish in stop and stop and stop and go traffic. This can't be normal, I even have a large radiator to prevent this. Could it be something with the rebuild? Any ideas?

May be your radiator is clogged...
 

Right after I got my Pineapple rebuilt/ported motor installed, my car ran really HOT! It got up to 121 C on the PFC. I am running Evans coolant and upgraded silicone seals too, so I'm guessing/hoping that my motor wasn't damaged.

I read on the forum that some one else had the same overheating problems after his rebuild and found that his fluidyn radiator got clogged by all the motor sealants that were used to reassemble his motor.

I ended up buying a Koyo radiator and my cooling problems went away. My car's heater core is now clogged and doesn't blow hot air anymore.

I'm pretty sure that the sealants found their way into my cooling system and gummed things up. That could be your problem too.

Try to flush your radiator or buy a new one.

are you talking in C or F? those temps don't make sense.

whoops sorry, I meant 245 F

when they rebuilt your motor, what kind of thermostat did they put in?

245F is around 118C

BTW the stop and go is murder for temps...having a large radiator with no air moving over it is useless....

I would double check that your fans are working...if you turn on ur parking lights do you see the temps go down?

well that sucks about the problems with your prestine fd

145 c is real hot 293 F to be exact which is nuts.
245 F is crazy as well the most ive ever seen in both my fds with stock radiators is 205 and I didn't like that.
You dont need to upgrade the radiator but it can't hurt.

you need to check the water pump and the thermostat and check to see if your fans are coming on and also see if your gauge is accurate with those numbers

there really isnt too much to the cooling system and youde be missing coolant if it was the engine

Thanks for responses, guess I left out a few thngs. I replaced the Thermostat when I put in the radiator, which was about 2-3 months ago. I also have the Miata Thermoswitch turning the fans on at ~208F. And both fans work properly. Also, I never had these heat prob before the rebuild, but it was also never 98F out side before the rebuild, since this heat wave just hit and I bought the car last November. Still, I can't beleive that a car would get released that can't sit at idle with the AC on and not overheat. Especially with my upgraded radiator.

Also, I don't have a temp guage, I poped the hood and used a laser temp gun at the coolant neck (very accurate).

Plus, when it gets that hot teh AC compressor starts surging on and of making my idle go nuts, which I assume is normal if the condensor just can't cool the freon.

what kind of thermostat did u use? some have been known to fail or not open at the advertised temp.

Did you go with a mazda OEM one?

umm you need to get a temp gauge or check it with the commander if you have a pfc...is your stock temp gauge moving at all? They move, ive found the one in my 94 to move perfectly unlike everything that others say without linearization. That laser temp gun Ive never heard of....did coolant spray all over you when you opened the thermostat housing?? you arent supposed to do that when the car is hot.

Any way DO the fan mod as well I can't live without it.
And your car has problems, this doesn't happen to normal fds. they didnt release a car that goes to 245 and blows the engine because its 90 degrees out. You have to recheck your cooling system one part at a time and there arent many. Check the fsm for symptoms of problems with each of the cooling system components.

I have stock ECU, so no PFC. With the temp gun, you don't have to take the cap off, just aim it at the metal. It is actually showing the temp of the coolant neck itself, but that should be almost the same temp as the coolant, most automotive shops use these guns. The first time I had this issue, yes the temp guage moved. Just barely started going above 9 oclock, to maybe 10 oclock and I pulled it over right away. And yes, I used the OEM thermostat. I have seen many posts in searching, about the rebuild cloging the radiator, I wonder how valid that is. i hate to sped another $350 on a new Koyo, when I just bought this one.

By the way, i don't need the fan mod. I have the TSB done and with the Miata switch, my fans stay on when I shut the car off anyway. unless it is under 208F, which is rare, and if it is, the fans don't really need to be on anyway.

I dont trust the reading of that gun.
you need to get a real temp gauge before driving the car regularly, especially since you are so concerned with the overheating and you have a new engine and a nice fd.

like I said the stock temp gauge going to 10clock position is normal that means your water temps were probably 200 or just above which is normal even with your thermosensor it will open at 208 which is kinda hot. do the fan mod and youll never see above 181F if you have the switch on. No need to switch out radiators for now try seeing the real temps with a gauge!

i trust the gun more then the gauges

well if the gun really reflects the coolant temp then you need to trouble shoot more.

are you sure BOTH fans turn on?

Re: May be your radiator is clogged...
 

Don't discount this post. There was a long thread about this a year or so ago. I seem to recall 2-3 people reporting this problem. All fixed with new radiators.:)

You might put the stock radiator back in if you still have it. Someone may have one laying around if you got rid of yours. Or just have to Koyo flow tested.

Sorry, but that reading with the gun is going to be totally bogus. Get a temp gauge or better yet the PFC, it's worth it.

This statment is simply not true for the vast majority of us. My car showed 112 C (~233 F) on the PFC and the stock gauge was at 9 o'clock. Noticed the stock gauge get to about 10 o'clock and the PFC showed 114 C (237 F). It truly is a dummy gauge.

Isn't it impossible for the heated engine metal to be an accurate reading for the coolant that is circulating through the radiator? Sounds to me that the filler neck HAS to be hotter then the liquid inside it.

Raj

mine lines up with the commander perfectly
that sucks for you guys I can use mine as a real gauge but i use the commander instead on the monitor feature with the water temp on the screen by itself its huge

if this guys engine went to 245 its gonna have problems in the future if not already