Recently my car was randomly overheating when it usually runs at 160 degrees. The coolant would jump from 160-210+ very rapidly. I then found that its leaking antifreeze really bad. I dont know if its building up too much pressure and then leaking? I do have a 15psi cap. I also found out that my heater core went out and leaked antrifreeze everywhere so i bypassed it. But the other times it leaked from the bottom middle of the radiator. Me and my mechanic took my radiator out and FOUND NO HOLES. But its random. It has not leaked since i bypassed the heater core but i got exposed to a new problem. After racing my friends mustang gt it jumped from 160-210 and climbed to 230 before i shut it off. I touched the radiator and it felt cool, around 80-90 degrees. This is the first time i experienced that also. My guess is that the thermostat sometimes sticks once it gets alot of pressure in the system and it remains closed. My fuel pump also went out that night and I was wondering if i should go with a new tbi fuel pump or switch to a mechanical.

Jegs Dual Corew Aluminum Radiator
Stewart Stage 2 Water Pump
Stewart 160 degree thermostat

 

Ok, i have an update. The heater core went bad so i bypassed it. I changed the cap to an 18 pound one and replaced the thermostat too. Radiator doesnt leak. I let it idle in the driveway for a half an hour and it was fine, took the motor from idle-5500 and held it at 3000 a few times. The thermostat was working fine. I go and drive down the road and its fine for the first 15 minutes. then the temperature started surging again. I touched the radiator and it was cool. No coolant in oil, or cc. It did start smoking once the motor got to 230 and i shut her down. Let it cool down and it stopped smoking and i finally got home.. F U C K

 

Your radiator could be clogged.
How fast were you going when it got hot?
Do you still have your air dam?
Seems funny that your radiator stays cool.
Are you sure your t-stat is good?

 

your water pump could be going bad if so the antifreeze leak you cant find is probably coming out of the weep hole on the bottoms side of it

 

might as well change the t-stat. even if that isn't the problem, you only wasted a few$

 

sounds like a air dam issue to me.

 

Got any white smoke coming out the back?

When my head gasket went on me, I had clean oil, clean coolant, but the car would randomly go from normal operating temp rapidly to max temp on the coolant gauge. After maybe 10 seconds of this, it would drop back down to normal operating temp. I wasn't leaking any coolant either.

Tended to happen after a full throttle run or else getting off the highway after driving normal speed for 20 minutes. Soon as I got off, it would just skyrocket.