Cooling System 1991 G20 35000 miles

[flowercuttings]

Radiator Issues

New radiator, new radiator cap x 2,
system has been properly bled,
radiator filled to the top when cold,
reserve tank filled to proper level,

When driven, water in the radiator enters the reserve or overflow tank as normal. On cool down, water is not drawn back into the radiator. Radiator holds pressure 14# and radiator holds vacuum. Its got me talking to myself. I can't figure it out. I'd appreciate any thoughts or help. Thank you

[SteveTheTech]

What kind of radiator cap are you using.

I've seen that many times where the cap sticks. But stranger things have happened. Honestly though all bets are off given the year and lack of mileage.