Engine Over Heat At Idle

[84LX89GT]

Originally posted by OnMy3rdStang
Nope all Rads from 87-93 are practically the same with exception to the 93 Cobra R model which had a degas bottle on it.

Now there was an HD radiator available but. The 2.3's use the same radiator stock as a 5.0 does....

2.3L mustangs have a one core radiator, whereas the 5.0L's came with 2 core radiators. Ford Motorsport offers a 3 core radiator for Fox Body cars, which is what i bought for my stang. My '91 2.3L mustang i had, had a tiny radiator and it literally has 1/2 the cooling ability of a 2 core because there's 1/2 the surface area for heat transfer. Also with painted fins, that seriously insulates heat transfer from the radiator to the air, which is probably the culprit in this case.
If you clean off or buy a new one core radiator for your car your car should be able to get rid of all that heat, a 2 or 3 core would cool off your engine alot faster as well, but it's pretty much overkill because 2.3's when working properly don't put out alot of heat. If i were you i would probably get a brand new radiator unless you're confident you can get all the chemicals off your radiator and the condition of the inside of the radiator is that it isn't rusted or anything like that. The fact that your cooling fan is constantly kicking on and even overheating the wiring shows that your car isn't able to shed enough heat from the radiator, especially if using the heater (heater core - mini radiator) helps cool it down.
Keep us posted on what you find.