FatDave747

Guys, yesterday in the bay area, the temperature got pretty hot. I was driving in stop and go traffic for a while and noticed my autometer temp gauge went close to 250 degrees F. I also looked at the stock water temp guage and it was above half way!!! I soon go onto the highway and after about 2-3 minutes of highway driving, the temperature needle was back at half way and my autometer was saying 210. This was the first time that this has ever happened in my car. I was wondering was it bad to have the needle above the middle (it was for about 8 minutes totatl) but the buzzer/light never came on.

matt_ledbetter

Using my Power FC to monitor temps, I have found that the stock gauge doesn't budge until temps hit about 114c. In my opinion, that is way too hot.

Are you sure your fans are working?

-Matt

FatDave747

Matt, my fans were running, I don't know if my second one was on though. I know when I turn on the AC, one of the fans turn on. Would having an upgraded radiator help in this case?

mmaragos

Yikes! I would be getting a little nervous at those temps. Time for a complete check up on the cooling system. Flush & fill, replace thermostat, inspect radiator, etc. Good time to check out the AST and hoses too.

If you still have the OEM radiator it could be on its last leg. Since you live close to the coast, it could have a ton of corrosion built up on it (reducing its heat transfer capacity). Mine was falling apart (tanks leaking, major pluggage on fins, etc.) after 86,000 miles and I am putting in a Fluidyne now.

The popular upgraded rads, Koyo, Fluidyne and Mazda Comp should all have more capacity than stock (when it was new) and definitely have more cooling capacity than a used stock radiator. Assuming all else is running well with your cooling system, then a radiator upgrade will probably cure all of your cooling concerns.

skotx

Guys, I asked a fan question the other day and no one responded. Now FatDave747's question has rekindled my interest. Do both fans work as one unit, i.e., do they both come on at the same time and spin at the same speed? I ask because one of mine (driver's side) was ground into the housing and now spins slower than the other. I need to know if I should replace it.

Thanks, and sorry to interrupt the thread.

As far as the topic, on hot days my stock temp gauge is often above half (probably because of the bum fan but also because of a FMIC). I haven't noticed any serious problems, but I always get nervous when it starts to creep.

alwan16

in my experience the stock gauge doesn't move till you're over at least 115C=239F. the worst part is that the buzzer doesn't go off till 125C-130C -> 257F-266F which means you are in deep $hit already. i'd make sure the fans are working 100% and if that doesn't work get an upgraded radiator. all rx-7 radiators are getting pretty old about now so they definitely are not as efficient as when they were new. plus it's been really hot out lately for the bay area...

mmaragos

Fans do not work as one unit, some situations you can get one fan in operation. Not too sure if they will go at the same speed. I believe that when both are on "high", they should have the same (similar) amp draw, but may not turn at the exact same RPM (because one is four blade and the other is five blade)...I don't think that you would be able to notice the speed difference with your eye though. Might be an effect of different number of blades or could possibly mean a fan motor trouble. I would check to see how much current each of them are drawing when your car is warmed up fully and they are both coming on to high speed. If they are close, I would think the motors are OK. Don't know what reference amps should be, but it should be in the shop manual.

twinturboteddy

It reached probably 100 degrees this passed weekend and I was stuck in traffic for almost an hour.

Water Temps never went above 91.

But my air temps soared to 72C!!!!!!


You guys need to pll your a/c fuse and run your fans on high all the time in that kind of heat. after traffic sorted through I maintained 88C in the bad heat.

matt_ledbetter

The car heating up on the freeway is a sign of a clogged radiator. If it cools down on the freeway, and runs excessively hot in traffic, I would check the fan operation. H20 to coolant ratio also.

Flushing the stock radiator won't do much good. That thing has very small passages inside and short of cracking it open, you won't get all the crap out. I replaced my stock radiator with a MazdaComp at about 80k miles. That seems to be when most people start having problems.

A quality radiator is never going to hurt, so you might want to start with that in the first place.

-Matt

potatobbq

Same exact thing happened to me today... I don't have an aftermarket temp gauge but my stock temp gauge went past halfway. I was also in stop and go traffic and I had the A/C on the 2 setting... This has happened to me once or twice before and it was also when the A/C was on. I don't think the fans are broken because once I stopped the car they did come on for 10 minutes. Could it be the fans aren't coming on when I'm driving? Seems like it's tied to having my A/C on... I already have a Koyo radiator and a Pettit aluminum AST. Any ideas? This hot weather lately is killing my car...

djantlive

Did you notice the fan blowing when sitting in traffic? Next time, turn on the parking light, it will make the fans come on earlier. Or, you can do the fan mod to manually turn on the fan.

If the temp ever comes on high and you can't pull over right away, turn on the heater. It will be hot as hell but you won't blow the engine. Avoid using AC while sitting in traffic on hot days bc it only makes your engine bay hotter.

Check the fan's operations by having the car idling for 5 minutes after a normal drive. If the fans don't come on, the relays are probably busted. Flushing the coolant and filling with more water % will probably help also.