Progressive coolant leaks at hose connections - coolant cap failure?

B 23 O FT 1988 740 Turbo

Since the onset of Minnesota Fall weather, we have experienced a series of coolant leaks at hose clamp connections. I am hoping we now do not have a head gasket failure.

In January of 2001 we rebuilt and installed the engine. The engine was sleeved, new pistons, the top of the block was milled true and the head was rebuilt. The original engine was well worn, had overheated and blown a head gasket. New headbolts were used. The engine assembly work was done in a warm basement and the engine was installed in a very cold garage. New coolant hoses and thermostat were used. The radiator was near new following an accident repair. Except for the failure of a front main seal the rebuild and operation has been perfect. About a month ago we flushed and refilled the cooling system with a 50/50 mixture-we did not overfill the system. The engine operating temperature has been and is the normal range. The car us used for routine commuting in the Minneapolis - Saint Paul area.

In the last 10-days we have experienced progressive leakage from about 4 or 5 hose clamp connections of the small and large coolant hoses. The leaks have been small (except the last) and easily corrected by re-tightening of the clamp. After finding and tightening another leaking hose yesterday afternoon, I am fearful of a head gasket leak. I explained away the apparent too loose clamps based upon installation of the engine in a very cold garage in January - the clamps were found to be firm. The last leak was a spray and not a drip.

I may now have a coolant leak at the head gasket on the right / passenger side of the block - or this may just be residual spray from the last spray type leak. If this is a head gasket, any comments regarding additional tightening of the headbolts?

A possible solution came to me while sleeping on the problem - was the new (green) Volvo coolant cap not relieving pressure?

Was the cooling system in-taking air in the cool nights and having difficulty venting off pressure when hot?

This morning, I installed the old gray coolant cap and let my son take the car to school.

What is my problem?

Does this appear to be a pressure relief problem?

Ideas and comments?