heating problem, hose collapses

any suggestions on what could be causing this will be appreciated.

If the problem was the radiator cap not venting, it would collapse the upper hose as well. Also, the lower hose is collapsing when the engine is hot, and the system should be under pressure.

I think someone forgot to replace the spring the last time the lower hose was replaced. I've never had the hoses off of a 3020, but I've never seen a lower radiator hose that didn't have one.

Course I haven't had that many hoses changed and haven't squeezed one lately. Had the radiator off a '62 4000 Ford the other day and no spring, but the hose was tough; probably didn't need it.

Thinking.

Until the thermostat opens the pump is sucking, but since there is no flow, it does nothing to hurt the hose (gotta push something out to suck something in).

Thinking more.

Then when water starts flowing, I'd say that the area of the tubes is greater (heck I know it is) than the area of the upper hose (under pump outlet pressure) and with gravity feed you have plenty of force on the lower hose (which is larger than the inlet on a lot of engines) probably to stop collapsing on both counts.

So it seems the only way you get enough suction on the bottom of the radiator (pump inlet) is for the volume of water going out of the pump to attempt to exceed the volume coming in which could translate to clogged pipes causing inlet suction and consequently sucking the hose shut.

Fun.

HTH.

Mark