I have just bought an RX7 FD 1994, the car overheats whenever I stop in traffic or in signal lights, stopping for 2 minutes makes the car temperature raise above 215 F but when I drive in the highway it drops to a normal temperature.

I have bought a new thermostat, new radiator and a new water pump, the fans are working perfectly fine and on high speed, there is no coolant leak what so ever and the water level in radiator is the same everyday.

Since the car temperature drops while driving it's for sure an issue in the car's coolant system not the engine but I can't figure out what is the problem.

 

It sounds like you're on the right track with replacing the cooling system. I would report back once you've overhauled things. It could be as simple as a partially blocked radiator.
Did you go with an aftermarket radiator like Koyo?
Does your car have the factory under tray?
Front mount intercooler or stock mounted?

 

Sounds like the radiator fans are not turning on. Are they?

 

Thanks for your reply, I don't know what type of radiator it's but I think that it's good enough, the intercooler is stock, I don't know about the under tray I have to go to the garage tomorrow to check.

The guy I bought the car from told me that the car has been sitting since a year, your reply gave me an insight regarding the radiator, It might be clogged because of that, first thing tomorrow would be cleaning it, thank you very much for your help and time.

 

[QUOTE=Cgotto6;12643964]Sounds like the radiator fans are not turning on. Are they?[/QUOTE
The fans turn on once I turn on the car, and they are in good condition. I have drove the car for an hour and checked them, they were turning on and in a good condition.

 

Are the fans running immediately with the key turned on? Even with the vehicle off? Or do they turn on only once the coolant temp has reached operating temperature?

 

Yes they run immediately when I turn the key on, when the vehicle is off, they are not running

 

Trey a different water temp sensor. There is likely a bung on the upper filler neck you can hook up one temperarily.

Do you still have an AST.? Check if it has the correct spec cap on it.

 

I'm wondering if there is too much gap around the radiator/fans and the air the fans are moving is recirculating through the radiator instead of drawing ambient air in and exhausting the hot air out.

That sort of thing is pretty common when stuff around the radiator and fans has been modified. In the FD it can be made worse by the fact that the engine compartment doesn't have real good venting.

 

A clogged cat or other blockage in your exhaust could cause the turbo to run hotter than normal.

Again check to see if your AST is working correctly. When the coolant gets hot enough, coolant should be flowing to the coolant reservoir and then get sucked back when your engine gets cooler.

One sign that the coolant reservoir is getting overfilled is that it may start to overflow. You will see coolant on the ground after you stop.

I had a similar overheating pattern on my car for years, until I learned I had the wrong cap on my aftermarket AST. I replaced the entire AST with a NOS one with proper cap and this largely remedied the overheating in traffic issues.

There is a chance your car was not properly burped after a coolant change and you have an air bubble in the system causing spot overheating.

The fans come on in stages with the final stage triggered separately. This final stage, that clicks in at 95 o C, may not be working on your car. Check the fan relays for a start.

 

Share some pictures of your setup. Stock fans on a stock replacement radiator should cool the car without trouble. What thermostat do you have and are you still using an AST in the stock configuration?

 

IMO, you shouldn't ignore the above possibility - if this is the case, it's cheap and easy to remedy. Everything else can be a lot more expensive and time-consuming. You may be surprised to see how many racecar cooling issues have been eliminated just by blocking unwanted air escape paths.

 

Thanks for everyone who replayed. It turned out that there is so much air inside the radiator, after taking the air out, the car runs perfectly and the temperature also is within normal range.

 

Awesome. Glad to hear you got it sorted out.