I have a 1999 Buick LeSabre that I had to replace the radiator. I did everything according to the book. The problem I encountered is that no matter how mush I had ran it, the upper and lower hoses wouldn't pressurize. Does anyone have any ideas as to what could be the cause?

 

Run it for a while with the radiator cap off and the heater turned on. Add coolent as the water level drops. If the A/C is on your heater core is by-past, wich causes a void in the system. Basically, just work the air out of the system.

Also,Check and replace thermostat. If its stuck open the water will not get up to tempature.