How long do you need to plug in your engine block heater before you can unplug, start your car, and be on your way? To save energy and money this winter, I plan to put mine on an automatic timer but I need to know how long to set it for. Is 20 minutes enough?

Engine block heater - how long does it take to warm up?

Tester November 30, 2007, 10:46pm 2

It depends on the ambient temperature. If it’s only 32 degrees outside, it may take an hour. If it’s -32 degrees it could take four hours. So figure anywhere between 2-3 hours on average.

Tester