For about a year, I've had a cooling problem and could not pinpoint the cause. I rarely overheat, usually it runs about 220-230 when it's hot outside. It mainly happens after driving for over 20 minutes, usually on a highway. I've replaced the heater core, tstat, cap, hoses, flushed and filled radiator, and made sure the belt is turning the water pump properly. Any ideas as to what is causing my problem?

Thanks!

 

you could always swap out the stock radiator for an aftermarket aluminum unit and/or throw on dual cooling fans.

 

Tried a cooler t-stat? I recently changed to a 170* and am really enjoying the change.