upper radiator hose collapses

[navyflyer72]

I am having a high temp problem. I have a 67 Camaro with a 327 that is somewhere around 375HP, I have a Be Cool direct fit aluminum radiator with a 16lb cap. I have a sealed recovery tank (only has the input fitting, and on the bottom has a petcock to drain it, no return fitting), I have the MKIII fan and DC controller wired to the battery junction block (battery is relocated to trunk), I have a 180* thermostat. When I start the engine the upper radiator gets sucked together. My temp runs at around 180* at hwy speeds, but in stop and go city driving it rapidly goes up to 210-215* I have both jumpers installed (pins 7-9 and 8-10) which should decrease operating temp by as much as 36*. I believe the major problem is the upper hose getting collapsed by vacuum from somewhere, what could be causing this and how do I fix it? Thanks for the help.

-George

[Rubes]

There is supposed to be a spring inside the hose to keep it from collapsing. But I would think the higher RPM at highway speed would collapse it more than stop and go.

[ZZ430]

The recovery tank is not vented to atmosphere. Loosen the petcock and I'll bet the hose won't collapse.

Tanks are available that are vented.

[baskin]

Coolant is not compressible, so the pressure can force air out of the tank through the smallest air leak. You only have 14.7 psi to force air back in. When the water cools and the hose collapses, the coolant is under less than atmospheric pressure, so it's likely to boil at a fairly low temperature. You don't need a lot of airflow into the purge tank. You can just drill a very small hole in the top of the tank. A 1/16" hole will probably be enough. On the DCC, the sensor is calibrated to +/- 3 degrees, so you shouldn't have to offset it at all. Do you have a picture of the sensor location?