forcfed7

when i am on the interstate or even able to drive at a constant speed everything is fine. if i get in traffic or have alot of top and go's it creeps up into extremly hot temps. so i have to pull over and let it cool. if the ac is on it happens even faster. now these cars couldn't have had this problem from the factory. what went wrong?

i have a 93 r1 with an aluminum radiator, new mazda thermostat, good hoses, (15%coolant, water, 1 bottle redline water wetter), and burped system. what else could it be? thanks!

911GT2

Do the radiator fans turn on?

forcfed7

yes and they seem to be working properly but not sure. i don't know how to check if they are blowing at their highest speed.

Mahjik

iTrader: (1)

Exactly what are "extremely hot temps"?

Do you have an aftermarket temp gauge or is the stock gauge actually rising above the half mark?

911GT2

I don't know about the fan speed check. There must be a way to do it though.

Have you tried swapping out a lower temp thermostat? KDR installed a 180F thermostat for me, it fits right in, it's actually the Miata thermo, so you can even get it from Mazduh.

forcfed7

stock gauge rises above half way mark.

what does the factory mazduh thermostat open at i thought it was 180

Mahjik

iTrader: (1)

Yea, it opens around there. What 911GT2 is referring to is the Miata Thermoswitch. It replaces the stock themoswitch to turn the fans on at a lower temp. You can also run with your parking lights on to get the fans to come on sooner as well. On extremely hot days (over 90) I do this.

Even without that, the stock gauge shouldn't be moving up past half way. I don't think it begins to move past halfway until around 250F.

Are you sure both fans are working?

EpitrochoidMan

ya, mazda thermostat opens at 180

spurvo

Well, 250F is a leeeetle exagerated I recall the tests showing the stock begins to deflect from 9:00 at 220F, and of course the stock system with lights off (just running lights, don't have to have the headlights on) the fans come on at 226F, which is a few degrees off 9:00 say 9:45 or so (what-the **** EVER!!). The lights on trick will get them to come on at 210F. Under both circumstance, the switch turns the fans off again at 195F. Stock thermoSTAT is 176F start to open, 180F nominally open, fully open at 200F.

Temps creeping up in stop and go is of course normal for our cars as there is not enough radiative surface (including enclosed areas above and behind the radiator) to allow the radiator to cool the car efficiently at standstill. This is as compared to an old Dodge pick up I had that basically didn't need a fan at all. BIG radiator with LOTSA space around it. Thus the rad fans. The temp they turn on is definataly higher than I think is good for the engine, so probably the easiest way to "set it and forget it" is to perform the Miata thermoswitch swap. For more interactive control over temps, the two variations on a fan mod are good, where you use a cabin mounted switch to control the fans. This really requires a temp gauge that actually responds to temperature fluctuations, so either linearize the stock one (really a pretty simple thing to do. Really!) or an aftermarket on if you like clutter

You're actually just fine, but like the rest of us, concerned about temps, which is healthy. Join the crowd of us down here that obsess about temps. Join us. It will feel so... right

Mahjik

iTrader: (1)

Just FYI, I can you that is NOT the case. I've seen over 220F on my temp gauge and the stock gauge hasn't budged.

forcfed7

ok thats sound good. what temp. does the miata thermoswitch come on. thanks for all the help.

Mahjik

iTrader: (1)

207F instead of the FD stock 226F.

More info here:
https://www.rx7club.com/forum/showth...threadid=26910

potatochobit

iTrader: (1)

if the stock temp gauge moves any time, then something is getting too hot. assuming no leaks and fans are good did you replace the water pump and thermostat yourself? check your belt for slippage. check the oil cooler.

KevinK2

Even stock set-up should control temps with ac off, stop and go traffic. Stock gage should not budge. Find your problem.

at idle, fans should come on before any gage motion.

coolant stays at top of filler neck?

rad properly ducted and sealed?

skotx

Just want to throw my two cents in to back this up. I ran overly hot one day last summer on the street. At 112C (~233F) my gauge was at 9:00. At few minutes later I noticed it creeping up, and my PFC read 114C (237F). This is why we should all hate the stock temp gauge.

spurvo

So sorry, was working from faulty memory.. (slinks away)

skunks

i have seen temps over 240F. on my car and the stock gauge not move a bit. in anycase, your fans should be on when the car is on, try making some airsheilds to force mroe air thru radiator.

talljosh85

iTrader: (3)

Does any body know what the part number is for this thermoswitch? Or what year miata this comes from. I need to pick one up, SoCal summers can get way hot. Thanks, Josh

DaedelGT

Call Ray Crowe at Malloy Mazda. Awsome, fairly knowledgeable guy, and he knows exactly what you need most of the time, including the thermoswitch. Offers a decent discount as well.

1-888-533-3400
Ask for the parts department of course.

Mahjik

iTrader: (1)

If you read the link I provided above, the part number is there....