1984 300SD coolant pressure

[ayrtonsenna]

Recently my 300SD began to overheat. After changing the radiator/hoses/tstat/coolant, the car now runs at 80*. When I parked it, I noticed the bypass hose (short hose between the tstat and water pump housings) was leaking pretty profusely from the top. I also noticed the top radiator hose was leaking. The hose clamp had loosened and the hose was about to fall off the radiator nipple. I went to pull it back onto the nipple and it fell off the tstat housing on the other end due to the pressure. Is this normal? Are the hose clamps just shot? (They look to be factory originals.) Is it likely I put too much coolant in? I thought it might be the head gasket but there haven't been any other symptoms of that with the car.