So I am starting to plug my truck in at night and when I plug it in it sounds like it is boiling and is quite loud. The 2001 that my dad has doesn't even make noise when plugged in. Is it common for them to sound like they are boiling?

 

Are you remembering to shut off the Cummins! Just kidding. My '01 makes some coffee pot noises, too. It's normal. I have mine hooked up to an outdoor timer now so it doesn't come on til 4:30 a.m. I figured if I don't run it all night the critters won't try to bed down under the hood as it gets pretty warm under there. Advantages are warm oil, quick defrost/heat and with the timer a slightly lower energy bill! Kurt

 

If it's boiling it's not normal! a slight sizzle like noise might be ok but I wouldn't be comfortable with it. If the element is getting hot enough to cause a boil it is probably shorted internally and only heating a small portion of the thing. It's not going to blow up or anything but it's going to fail before too long.
I've worked with a lot of hot starts before but none of them actually kept the engine WARMER then running temp

 

I have always heard noise like what was described as "coffee pot noise". If you are really worried, take the cap off and read the temp with a therometer. That should settle the question.

 

Coffee pot sounds about right. Just was curious because mine was so loud. Thanks for the responses.

 

Another vote for the Coffee Maker sound. Never heard it put that way but that exactly describes what I hear.

How cold has it been getting where you are from SkiDoo? Upper teens to lower 20's at night here in Idaho but looks to be cooling off a bit this week.