cooling system problem

[blues14]

I just had a low km ka24e dropped into my 89 240sx. I drove the car to work today for the first time with no problems. left work and stopped at my local garage and noticed my car was leaking coolant at a fairly rapid rate. so i opened the hood and saw that the coolant was leaking from the upper radiator hose at the clamp on the head. also, there was a lot of pressure on the upper hose to the point i could barely squeeze it. so i let the car cool down for about 15 minutes and decide to drive to my house with the heater on full blast, aprox 3 miles. the car never got above normal operating temp and had no leak and no built up pressure on the hose. It was like nothing ever happened. I let it cool down and opened the cap and started it and you could see the coolant flowing. What happened?

[navysnail]

i would check the clamp, hose, and attachment point on the head for defects.

[blues14]

ya, but a loose clamp isnt going to cause a hose to build up pressure. i am starting to think that the thermostat got stuck. so i am going to replace the hose and the stat. better safe than sorry:) but if anybody else has ideas, they are of course welcome to post.. could the water pump cause this pressure build up?