Hi guys

In October of last year, I replaced the head gasket on my 1993 5.7L LT1 Trans Am. Everything was great until earlier this month when I noticed that I was losing coolant. I saw some hoses that appeared to be leaking at the clamps and I replaced them. In doing so, I also replaced the thermostat and the water pump. I tested the new thermostat in a pot of boiling water, and it tested good. Immediately afterwards something different started happening. On a daily basis I'm finding a puddle of coolant under the reservoir tank. The radiator is low, and the reservoir tank looks overfilled. In fact, the coolant seems to be coming out the top of the reservoir tank, and leaking on the ground. There is no coolant in the oil, and the car is not overheating. I do not see any coolant or white smoke coming out of the exhaust. I also pressure tested the system and found no leaks and it held 18lbs of pressure. All the coolant lines are attached to the right places, including the reservoir line and the steam pipe line. The cap appears to be in good working order.

Would anyone have an idea of what could cause the coolant to be backing up from the radiator to the reservoir on a daily basis? It's a PITA having to fill the radiator up every morning!

Thank you so much in advance

 

Radiator cap

 

You say its a lt1. Did you bleed the system of air bubbles with the bleeders on the engine? Does it run hot?