So I replaced the stock radiator in my 93 with a 53mm Koyo and 1.3 bar Greddy cap. The water temps have actually gone up now and the area right above the radiator at the front of the engine bay gets ungodly hot. There's plenty of coolant and the fans are kicking on. I can smell what seems like burnt coolant when the car gets shut off. The AST is stock but is not leaking. Any idea what the problem could be? Thermostat?

 

Make sure your radiator hoses aren't kinked and your belly-pan is in place. What ratio of coolant to water are you running? The more water (distilled) to coolant you can get away with the better. Are you getting ALL fan speeds? Did you bleed/burp the system of all the air...no boiling sounds?
Personally I would also return to a .9 bar cap.

 

^ What he said about pressure cap and water/coolant ratio. How hot is ungodly hot? Do you have a number from an aftermarket gauge or notice any movement from the stock gauge? Also what thermal switch are you running, FD or FC?

 

i have the greddy cap and mine never goes past 86 degrees

 

I'm running a 50/50 mix of green coolant. Lines were bled, no boiling sounds. Belly pan is there. The fans seem to kick on at the same time and speed as before. Thermal switch would be the normal FD one. I'm getting water temp readings from the PFC and they easily break 92C now with an ambient of 70F, before they wouldn't get above mid 80s unless I was in some stop-n-go for awhile. Oh and ungodly hot means I can't touch the end of the hood without coming close to burning my hand

 

Does it make a difference if your moving vs. relying on the fans? The only other suggestion I can think of is to go back over your work...double check the radiator hoses etc. You MIGHT have a sticking t-stat, but that's not common in my experience.
92 C. is a bit hot for those ambients. There's something going on.

 

Try switching to 75/25 Coolant/water. I don't know if you have to worry at 92C, does it stay at 92C or does it continue to climb? I'm assuming it does since the stock thermal switch doesn't kick on the fans till 96C, like Sgtblue said check the t-stat, it could be sticking. You can also find out what temperature the stock fans turn on, if it's later than it supposed to then most likely you have a sticky t-stat.

At 70F ambient my water temp is about 180F cruising or 195F in stop and go traffic, and I have a Koyo N-FLO and a 0.9bar cap.

 

So I've discovered that the fans don't kick on now until 92C, which is why the temps seem to hover there. Before the fans would kick on much lower, 85C I think. The vendor I got the PFC from programmed it to do that...and unfortunately I can't change the setting with out the FC-Datalogit software and box ($299). Any idea why the fan temp kick-on would change but nothing else from a radiator install??

 

92 C might be higher than it was previously, but it's not too high. The stock FD thermoswitch activated fans at 108 C. and the S5 thermoswtich (which many of us have installed in it's place) only lowers it to 95 C.

 

I thought the FC switch activate at 195F which is 90.5C?