I think I have air trapped in my cooling system. It all started when I removed some temp sensors from my cylinder heads and moved them to the manifold. I lost some coolant when removing the sensors so I topped off the radiator and let the car run with the cap off until the t-stat opened and I continued to add coolant until the radiator was full. But with the cap on and the car running when I rev it up the lower radiator hose collapses and the upper hose expands, and when I shut off the car I can hear bubbling or gurgling inside the motor. So I think there is air trapped inside the motor somewhere but I can't seem to get it out. After the car sits overnight the radiator is still full. I have a few small holes drilled in the t-stat, all hoses are new, the radiator and cap is new. I've searched on here but I haven't found anything to work to try to get the air out. Any help is much appreciated.

i drilled and tapped the top of my t-stat housing for a bleeder screw. this is the highest point of my system.warm up engine and open bleeder till coolant comes out steady. The newer traverse engines have multiple bleeders.....

Thats a good idea, but I'd rather not have to drill and tap my housing if I don't have to.

If the radiator cap is higher than the thermostat housing...you have NO need for bleeder screws.

You don't have air trapped in the system. You MIGHT have a restricted radiator--partially plugged with scale or rust.

You'd do well to add a reinforcing spring to the lower rad hose; or replace the hose. For that matter, if the upper hose is ballooning, it might be time for a replacement upper hose, too.

The radiator cap is higher than the t-stat housing. Both the upper and lower hoses are new, the lower hose does not have a spring, but from what I've read it sounds like newer molded hoses do not need a spring. The upper hose only expands a little when the lower one collapses when I rev it up. I finished building this car last fall and I drove it a little before winter and everything was good. I haven't driven the car this year yet and the only thing I've changed is moving the sensors in the heads. The only reason I think there is still air in the system is because after I shut the car off I can hear bubbling in the motor. Everything in the cooling system is new. I don't know if I should maybe drain the hole system and flush it and refill.