lookin for some figures

[cranbrookbushbomber]

does anyone have any idea what the standard operating pressure would be in the rad when the kzn130 3litre td is at idle?? Just wondering if i could use a pressure test on the rad to help diagnose any potential head issues on a couple of different surf's i'll be looking into purchasing. Also any other diagnostic tips or "things to look for" in general would be welcome. Thanks by the way for all the warm greetings since i joined. i look forward to interacting with the group!!

[surfenstein]

not sure but there is usually something stamped on the rad cap in kpa.

[meooo]

normal operating pressure for a cooling system is 12/13psi, but you would have to connect your pressure tester from cold, as once its hot it shouldnt produce pressure, as the coolant has expanded by way of releasing the cap (unless theres a head gasket/cyl head problem of course)

[cranbrookbushbomber]

12-13psi

so is there any idea on what kind of psi a cracked head would produce, would i be looking at at least a 5 lb increase over standard operating pressure?? Thanks for your responses by the way

[Taliesins]

normal operating pressure for a cooling system is 12/13psi, but you would have to connect your pressure tester from cold, as once its hot it shouldnt produce pressure, as the coolant has expanded by way of releasing the cap (unless theres a head gasket/cyl head problem of course)

I think you will find there is pressure when its hot, otherwise the system wouldn't work. The system is designed so that when the pressure in the radiator exceeds that which the cap allows, excess coolant is spilled past the cap into the reservoir. When the cooling system cools, and pressure inside falls below the normal atmospheric pressure outside, any coolant in the reservoir is sucked back in past the radiator cap.
Just thought I would mention it as people may get the wrong idea.

[BioHazard]

The best way to tell would be a block tester. The liquid changes colour if exhaust gasses are present in the coolant, the only thing is you will need to check it over a period of time as small cracks take longer to show up, Dranglegrinder once told me that one took 20 minuets to be detected as it was in the early stages and the cracks were small.

[NiftyNev]

so is there any idea on what kind of psi a cracked head would produce, would i be looking at at least a 5 lb increase over standard operating pressure??

You would get 450PSI or there abouts. The cooling system can't hold that pressure of course and it would be released through the cap or anywhere else it could go. In severe cases with a lot of pressure released quickly and not being able to vent quickly the radiator can explode.

Nev