overheating FC
 

alright so me and my girlfriend fixed up a few things that needed to be done to the Turbo II FC she bought herself a few days ago and something happened that kinda concerns me.

were on a cruise everything is fine but after say maybe 30 mins of driving we stop at a 7-11 to get some drinks. while we were inside we let the car turbo time outside so when we got back to the car it was still running but the coolant temp was about 3/4 the way toward the H . so we gotta start driving to get some airflow through the rad to cool the car down , sure enough that works , coolant goes back down to normal. but when we are stopped at a red light and again it slowly starts to rise again. We get home and try to turbo time it for atleast a couple seconds until the coolant temp almost reached the H. Coolant was boiling in the coolant reservoir.

car is home now, im ready to work on it , i just dont know what to look at first.


In short , car overheats bad when you drive it for a while.

Thanks guys.

First off, don't waste time with turbo timers or letting it idle after your drive. The stock turbo is both water and oil cooled, and will disperse heat very quickly. There is no need to idle forever, and in your case it's just leading to overheating.

If the engine cools down while moving, but heats up when still, I would say the fan is a likely suspect. If it's the stock clutch fan, there's the possibility that it is not locking up properly anymore. When hot air passes over the fan, the metal clutch assembly in the center locks up and allows it to pull more air. If it never reaches this point, the fan will not move as much air as it should be.

If the car is using an aftermarket electric fan:
1) The fan may not be working
2) The fan may be too small & not pull enough air
3) The thermostatic switch or whatever is controlling the fan may be wrong/set wrong

Other things to consider:
1) Does the car have the plastic undertray to direct airflow to the radiator & oil cooler?
2) Is the car smoking or losing coolant quickly, and will it begin to overheat within minutes of running? (Signs of possible blown coolant seals)

cool thanks alot rocket.

i know the coolant seal isn't broken because its not losing coolant quickly and this overheat happened after a good hour of driving the car.

alright so im gonna look into changing the clutch fan.


another question , if i wanted to bleed the coolant properly how do i go about doing this ? i know there is a coolant bleeder on the block or rotor housing ... whatever the proper term is. but where is the coolant bleeder on the top for the radiator and such ?

There is no bleeder on the block; just a drain plug near the driver-side engine mount.

The bleed screw is on the radiator's upper hose connection, next to the air filter. Loosen it so some air can escape, then top off the cooling system until coolant comes out past the bleeder screw. Tighten the bleeder and add a little coolant until full.

replacing clutch fan with electric fan
 

So apparently FC's are notorious for the clutch fan not locking up properly and leading the motor to overheat. so i bought an electric fan to replace the stock clutch fan.

my question is whats the best way to wire up an electric fan on these cars ?

are there any wires around the engine bay that are easily accessible ?

the fan did come with a controller but im not sure whether to use the controller or wire it so the fan is on constantly.

Notorious? It's actually not common at all, but it can happen. Going back to your other thread, did you test the clutch fan at all? You could just find a used one and odds are very good it will work fine.

Don't wire the fan to run at all times. That would be a mistake. Either use a temperature switch, or a good fan controller. Many of the cheap ones that come with aftermarket fans have a habit of failing. I've had a cheap one fail and cause my fan to stop altogether.

Aaron has a write-up here: http://www.aaroncake.net/RX-7/efaninstall.htm

I also have a write-up for my blackmagic 150 fan & SPAL fan controller here: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/spal-pwm-v3-black-magic-150-install-851238/.

hmm , well i went to my local rx7 specialists and they did say the clutch fan is "notorious" but i guess it did just happen on my part.
thanks for the write ups , they help alot.

Yeah, your local RX-7 "specialists" in Calgary will tell you a lot of stuff....And I'm sure they believe it all.

I would urge you to get an electric fan if possible.

keeps overheating/overflowing
 

So i've done just about everything with the cooling system to my 87 FC Turbo but it keeps overflowing and overheating. it only overheats after driving for a while though, not right away.

after driving for a short period of time the coolant overflow gets full and keeps overflowing.

i've cleaned the coolant system with radiator flush.

installed a new thermostat.

i've got rid of the clutch fan and installed an electric fan.


whats the problem here ? im ready to change the radiator or the water pump if i have to.

another thing i noticed is that when i squeeze the lower rad hose , it feels like there is a spring inside ... i donno but somthing is inside there, not sure if its supposed to be like that or what.

thanks guys

As I recall there is a spring in the lower rad hose to prevent it from collapsing under suction.

With the car warm, run you hand over the rad. Are there cold spots? If so, then it could be clogged.

Water pumps don't usually fail, but the impeller can corrode away so it would be at least worthwhile to remove it and inspect it.

it would be hard to look for cold spots on the rad cause i have a big electric fan with a shroud installed.

but the clogged radiator is a good thought as to why its overflowing.

thanks man