My fridge pops the breaker, except when the element is isolated from everything else metal in the compartment?

i've change the startup capacitor, defrost timer and element. when the element is not connected, the fridge runs through the defrost cycle. when connected, it pops the breaker. when the element is connected BUT NOT touching anything else metal in the compartment like the cooling coil, it runs fine, heats up, finishes, goes back into cooling cycle, so i'm leaning towards a grounding issue. how would i start to hunt that down? what should be grounded to what and what should i check with the ohm meter?