I am curious since this is my first diesel.....

How long can one leave the engine block heater plugged in? If I do not drive the truck for several days and it is cold out like today ~18 degrees. How long can I leave the truck plugged in?

 

At 18ºF you shouldn't even need a block heater, the truck should start just fine using the glow plugs/grid heater. Then take it easy on it for a few miles. If you use one at that temp anyway you will likely only need 2-3 hours at most. I use a timer on my truck that kicks on 4 hours before I plan to leave and that is when it is near 0ºF.

If you want to leave it plugged in longer at that temp you are just using electricity, so you make the call on how long you want it running.

 

I have no doubt that it will start fine even in colder temps. My only problem is that I work only about 1-2 miles from home. There is no way to get to operating temps when driving that distance. Not to mention that you will never get any heat coming out of the vents.

 

Well, a diesel is not really ever going to get warmed up in that short of a distance no matter how long it is plugged in. At 18º you could leave it plugged in 24-7 and it wouldn't help. A gasser won't even warm up in 1-2 miles. Not sure what to tell you other than to keep it parked in a heated garage.

 

I live in Boulder, Colorado so we see some cold weather each year. Actually 4 deg F here right now and going to -6 deg F tonight. My 2014 F350 with the 6.7 diesel sits outside all year round because the stupid garage is too small. I've never used the engine block heater in three years and it always starts fine. It just wants a little time to warm up before heading out.

I have discovered that I need to use diesel fuel additive in this kind of super cold to keep the fuel from gelling up.

 

What fuel additive do you use?

 

Curious, does the remote start on Diesel engine trucks work any diffferently than on the gas trucks? Does it have a delayed start giving the glo plugs time to get hot? Always wondered...

 

Yes, it does. In fact, when I bought my 2014, the dealer told me that remote start was the preferred method for that very reason.

Not sure I buy this, but it does make some sense.

 

I'd be more concerned the battery will get horked, they get pricey when bought in pairs.

 

I have used many different ones over the years. It usually comes down to what's on special at the auto parts store.

Here is a link to an article reviewing some of the top ones:
What is the best Diesel Anti Gel Additive for your fuel tank?

 

I have used battery heater blanket wraps in prior trucks, but we lived up in the foothills then and it was much colder, much more often. Knock on wood, but it's not been an issue on my F350 - at least not yet.

 

I guess the simpler question would be is there any drawback to leaving it plugged in for long periods? Does the heater prematurely wear out? How warm does it keep the coolant?

 

i think it takes 3 hours to reach its max temp, after that your just wasting power, that said it would have to be really Fing cold for this truck not to start, i have started my old truck (2016 with 6.7) in -45c with out plugin it in and rolled over fine, my new truck this morning at -35c. i know its not good for it and i try to plug it in as much as i can but its good to know that it wont let you down! that said let it warm up before moving it!!!

 

There is an immersion heater in the block in place of one of the soft plugs. They draw between 1100 and 1500 watts so they are power hungry. Make sure to use a 12 ga extension cord and be sure the receptacle is in good shape. There have been many building fires started by faulty wiring to a block heater and even the wiring on the block heater itself.

There should be no long term damage caused by extended periods of block heater use. The 6.7 is engineered to start as low as -20f without the heater but having a little heat during extreme cold is never a bad thing. I have a plug in type timer with mechanical pin settings (15amp) and set the timer for 2 hours before I intend to start up. Saves spinning the power meter all night. My 7.3 likes to be warmed if temps drop below 20f deg. If I were keeping the truck through another winter I would change the starter out for a newer style gear drive which spins the engine substantially faster for starting, a big help when very cold. Heck, maybe I should change it anyway with the delivery schedule Ford has imposed on me. Lastly it doesn't make the coolant warm throughout, only on the left bank. Sounds kind of artsy as in Paris? It does make a little earlier warm up to heat the cab, but not much.

 

Not heat related. Charging. Glow plugs and Diesels... It's not going to get charged back up in a mile or two... Daily short trips can cause trouble.