if i plug the cummins in for say 2 hours before i leave when its like 20 degrees ooutside will that help it warm up or not. if not what exactly does the block heater do for the engine.

 

Yes but you need to remember that it takes alot to wam up all that engine and all that oil, etc i would say if you put it on a heavy duty timer and run it about 5 hours that should do it. Thats what i do

 

The block heater is located in the coolant. It warms up the entire block by convection. I would say 2 hours would be the minimum. A timer works great if you know what time of the day you leave. 3-5 hours depending on the temp.

 

A lot of guys on here may disagree, but I've found it to be most effective if I plug it in as soon as I shut it off. This way the block heater doesn't have to heat it from say 20 degrees. It just has to keep it warm. This method seems to produce warm air from the heater as soon as I get in it. Where as when I had it on a timer set to come on 3.5 hours before leaving for work it wasn't very warm. It's also warm anytime I want to go somewhere. Just my .02. Paul