My name is Sondra n I just bought my Cadillac. It ran hot so I replaced the thermostat after realizing it needed it. Engine fans not working and hose coming from radiator is building up air pressure instead of water pressure. Also still runs hot. Also the reservoir is building up air pressure. What could fix this problem. Heater also does not blow hot air but it will blow out cold air instead.
Your engine may be a two part aluminum block which the block design is weak and should be resealed. You may also have your engine block head bolts inspected, this design has a characteristic of having head bolts pull from the block that need to be re-threaded and may be costly.