Should a block heater make noise?
Should a block heater make noise? The noise you hear is akin to a pot about to boil. Given the XJ's block heater is an immersion heater in the water jacket (freeze plug fit) that should be the sound you hear, albeit faint and only after the heater is plugged in for 10-15 seconds or so. How long do you leave block heater plugged in? One thing that most can agree on is that the maximum amount of time you should leave the engine block heater plugged in for is four hours. Any more and you're just wasting electricity. You...