Under What Temp. Will an FD Overheat?
 

Today was so hot I couldnt drive (74 F), I didnt want to overheat it in the traffic. So at what point do you have to start worrying?

Assuming I'm just cruising under 3k rpms without boosting.

You dont have to worry about it overheating in 74 degree weather. If you want to be able to keep tabs on the water temp get a gauge. And you may want to do the fan mod. Or if you don't care too much about having A/C you can pull the A/C relay out of the relay box in the engine compartment, if you do that all you have to do is turn the blower on 3 and turn the A/C on. the light will come on but the A/C will not be working due to the missing relay (I.E. the computer thinks its on so it kicks the fans on high). This way whenever you have the A/C on the fans will run on high. This helped me out a lot. It made as high as a 10 deg. C drop in temp on hot days.

The damn A/C will kill the engine when idling, I have yet to fix the problem.

74F is not hot, just wait till summer, it'll go over 100F eventually. Yes, in San Jose.

You should really make sure that everything is working properly in the cooling system. Flush the radiator abd put in a 70/30 water/coolant mix. Replace the thermostat. Make sure your fans work properly. And do the fan mod with a switch to turn the fans on whenever you want. ANd if you want to be really safe, install a temp. guage or linearize the stock one.

a more direct question:

after one gets a gauge and monitors the temp, at what degree on the gauge will the engine overheat? what temp is considered too hot?

It will probably be fine. I would bet that your car is dieing when you turn it on cause the idle is a bit low and the A/C boggs it down.

But when you pull the A/C relay the A/C doesnt actually come on, the computer just thinks it does.

With my PFC during the summer I will occasionally see temps as high as 115 C and the needle hasn't started to move yet. It will only get this hot after driving around town on a 95+F day. And those temps are right after I start it back up after stoping someplace, as soon as the engine is running it will cool down in a few seconds.

anything above 110C is not "normal" under any circumstances. the stock needle won't move till about 120C-125C and the buzzer doens't kick in until 125C-130C. don't ask me how i know :(

Evans NPG is the sheeeeeit~ 0 pressure, no water therefore coronsion proof. Right now it is 80F outside I get 87C(188.6F) on my power FC.
read about it in the single turbo section
https://www.rx7club.com/forum/showth...threadid=31518

David

Dont the radiator fans come on whenever you turn on the blower and A/C?

The fans turn on at 110C, which, IMO, is too late. I've had it up to 115C once before I pulled over. I think around 120-125C is when the coolant will start to boil depeding on your mixture, then you're usually screwed.

Hi,

When you put in the Evans, did you drain the old coolant from the block? Plus, I heard you need to do something to the radiator cap to to make it 0 psi?

So, should I give a gas to help the idle? Or that's not a good idea

If I drive the car (not idling) with the AC and blower on, then the engine might not be killed by the AC. But is that a good idea?

If you had a water temperature guage (which you don't) you would know that anything over 110 degrees celsius is overheating. stop and go traffic is the worse, as it can make the water temps jump. Anything below 110 is ok, but since you only have the stock guage, if the tack goes anything above the middle that means it's over 110

What about 1800°F? Is that too high?

230-240 F is getting dangerous...250 F is very bad.

Once running on the highway at speed you should see 170-180 F.

Check out Steve's site:

http://www.scuderiaciriani.com/rx7/cooling.html#TEM

Patrick

I'm gonna try driving with the AC and blower on tomorrow and see what happens.

thank you.

I just drained the old coolent and then filled it with straight Sierra coolent and ran it for about 2 weeks and then I drained it all again. Then I filled it up with Evans. No, I did not drain the block, since I didn't know how :P but I think the Sierra took care of all the water that was in the system and also the Sierra was compatible with the Evans, so I didn't really bother completely draining the system.

As for the 0 pressure cap you just need to remove the spring assembly underneath the caps. Or you can just use the stock cap that was on the water housing, that is a 0 pressure cap.

David

Why does everyone think the fans come on at 110C (230F)? The low speed fans come on at 105C (221F) and the medium speed fans come on at 108C (226F). Ever since I upgraded to Fluidyne, I've never seen more than 221F, that is, if I let it idle long enough, the temp will slowly creep up to 221, the low speed fans come on for about 30 seconds, and the temp drops back down to 180F. Moving the car keeps it around 180F. Also, the A/C turns on the fans at low speed no matter what, so whenever I have the A/C on, the temps stay at 180F. I've haven't really stressed the cooling system, but even in rush hour with the A/C on a warm day, it just stays rock solid at 180, so I give a big thumbs up to the Fluidyne for that. As far as the temp gauge goes, I've personally observed there is a very very minute range in the "middle" range that corresponds to 180-230 roughly, that is, I can tell the difference between 180 and 220 just by looking at the stock gauge, but the differences are very small, maybe 4-5 angular degrees. The stock gauge doesn't start to move up significantly until 230 or so, and I'd say you start decreasing engine life at 230, 240 is very bad, and 250 (which corresponds to the top white line I believe) for any length of time and you probably toasted the motor.

teh last ditch high fan thermoswitch comes on at 108C, that is also when the needle is at 3/4 on stock gauge. while driving anythign above 110C is bad. I fyour fans aren;t coming on unil 108C then you have a problem, the fans will come on before that with readings from thermosensor, then thermoswitch does 108C irrelevant of gauge, etc.

FWIW My low speed fans come on at 99degC with an SR "tuned" PFC.
From the perspective of a guy who takes his car to the track quite often I can offer this data point.
Since using the PFC I have been recording my max values from the PFC after each track session. For example with ambient airtemps in the high 80 to low 90 deg F range, I see max coolant temps between 105 and 110degC with the maximum ever of 111degC.
This is driving the car HARD for 20-30 minutes straight - with many WOT bursts and with the engine always in the 5000-8000RPM range.
I have a well sealed MazdaComp radiator and run
60/40 coolant mix with a bottle of Water Wetter...that's all.

All I can say is if you are seeing more than 110degC during normal street driving you got problems.

Hope this helps.
Regards,
Crispy