Engine gets a little hotter for a minute or so when you shut it off - no circulation. The rad cap should never have allowed that much pressure to build up. I'd toss it as far as I could. Or take it back and get a new one.

 

Thanks for all the replies. I repositioned the cap again. Its a Stant, so I dont think I went cheap. I took it for a short drive and everything seemed ok. Also tried the burp technique with the upper hose. Is it possible new rad/new coolant can expose some other problems you guys talked about like water pump, thermostat, temp sensors, etc?

 

If it overheats when sitting but not while driving your fan clutch is probably shot. If it overheats while driving your WP is probably bad. Thermostats are designed so that when they go bad they stay open, so unless there is something clogging the therm that probably isn't your problem. Since you replaced the rad/coolant it is possible that you loosened some deposits up and they may be clogging your cooling system somewhere. Always flush the entire cooling system when changing any part out for this reason. A 5 minute flush can save an engine from frying gaskets and overheating to the point you do major damage.

More than likely you just had a lot of air in the system, this is why I always recommend putting in a flush kit when doing any cooling system work, they are $4 at walmart (Prestone brand), last forever, save a lot of time flushing and refilling system.

 

FLT is right, you probably just moved stuff around the system if you didnt fully flush. There is also good advice there about the pump vs. the fan clutch. Coolant systems are easy to work with since they dont go into other parts, and other than the engine block, every piece is removable.

Also, filling your radiator is harder that people let on. You have to let it sit, and even run the motor a few minutes, turn it off, and add again. one good air bubble can fry alot, from the cap to the sensors.