Overheating in traffic, coolant leak near rad
 

Ive been struggling with the cooling system on my fc for many months on and off now. It will only overheat in traffic (I have replaced the clutch fan), highway driving it stays at about 1/4 on the temp gauge. In traffic the temp creeps up to around 1/2 or more. I have replaced the thermostat, done a coolant flush and burped the system. I also have a coolant leak near the rad, but only after shutting the car off. The leak stops after about 5-10 minutes. No white clouds of smoke coming from exhaust, and no smell of burning coolant from the exhaust either. I have ran the car without the rad cap, it bubbles until the car is warm and then the bubbles go away. Any ideas help!

Could be a partially clogged rad. Or maybe you have a second bad clutch fan. To test for a clogged rad, wait till the car is completely cold. Take the fan shroud off, leave the hood open and start the car. The moment the car reaches 1/4 on the gauge, shut the car off. Then go to the engine bay and carefully feel the different parts of the rad. It should be uniformly hot, without hot or cold spots..

To test the fan clutch, wait till the car is warm (alternatively, you could use a heat gun to blast hot air on the clutch for a minute or two) and then, with the engine off, try to spin the fan. If it is easy to spin, or spins for a long time after you let go, the clutch is bad.

As for the leak, is it from a hose or the rad cap? Replace the faulty part as soon as you can, as the leak will only increase in size. Also, if there is a leak, you may be losing some pressure, which can cause the coolant to boil at a lower temperature.

Alright I will give that a shot, thanks!

So I just got back from taking it for a drive, its now overheating in general and not just in traffic. I checked the clutch fan and it wasn't spinning more than 1 rotation when I flicked it. I didn't see anything leaking this time either.

Is it possible the leak you saw was from the weep hole on the bottom of your water pump?

Make sure to put the shroud back on after you test your radiator.

Your cooling system has a leak. That means it's probably not pulling coolant out of the overflow as then engine cools down. And that means it's possible you're coolant level is low and/or you have air in the system. You need to thoroughly check hoses and radiator and get the leak addressed. Most chain parts stores here in the states will 'loan' a coolant system pressure tester for free.
If the FC temperature gauge is like the FD gauge, then it's worse than useless as it's not linear. If it moves from it's 'normal' fully warmed-up position at all, then it's over-heating.

OPs profile lists an 88 GTU. Assuming that this is the car in question, the gauge should be at 1/4 when warm. Anywhere above 1/3 is "too hot", but not necessarily dangerous. Above 1/2 I would get nervous about my coolant seals (although I don't think it is hot enough to do any damage until far higher) but then I'm no expert.

Anywhere after 88, the gauge should remain firmly planted at 1/2. If it has risen past 1/2, you are already in the danger zone.

I should note that the gauge isn't necessarily trustworthy after all these years. An after-market gauge is always a good idea.

Yes I am planning on buying an aftermarket gauge asap.

Install new thermostat no matter what. Get aftermarket temp gauge-best you can find with biggest scale. Water pump will tell you when it has a problem. Check coolant level constantly until resolved. Temp kills rotary's. Not much else matters. Don't run hot, at all.

Had an overheating issues in the past with one of my cars. Changed the thermostat, burped the system, checked the electric fans, but the problem would keep coming back.

Turned out to be a cheap radiator cap that had too low of a pressure rating put on by the previous owner. It allowed coolant to make it into the overflow and out the bottom of the car. Over time the radiator would slowly empty and air pockets would form in the engine. I think I spent a few hundred dollars chasing the problem, only to solve it with a new $20 radiator cap.

Lessons don't come free I guess

Replacing older caps is fine, but that should NOT be taken as a suggestion to get a higher than stock pressure rated cap.