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Running Engine with Block Heater on

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Old Dec 20, 2024 | 10:59 PM
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Running Engine with Block Heater on

Ford manual says to unplug the block heater before starting the engine. Doesn’t say why.

A quick search results in multiple lay people saying it’s not required.

The manual for my block heater controller says to never run the engine with block heater on as it can ruin the heater.



Perhaps block heater failures are due to people not unplugging them before starting.

Definitely a bummer for those that want to start the truck remotely while plugged in.
 
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Old Dec 21, 2024 | 07:11 AM
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I’m curious too. I ran my Cummins trucks with it still plugged in, and I did with my 2018 6.2L a few times as well.
 
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Old Dec 21, 2024 | 07:29 AM
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Most that I know leave the heater plugged in, remote start the truck, then unplug before they get in to drive away. I'm sure some have left it in and then drove off, dragging an extension cord with them.
 
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Old Dec 21, 2024 | 09:29 AM
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I haven't even found my block heater yet. A heated barn is a nice thing to have.
 
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Old Dec 21, 2024 | 09:44 AM
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Originally Posted by ShotgunZ71
Most that I know leave the heater plugged in, remote start the truck, then unplug before they get in to drive away. I'm sure some have left it in and then drove off, dragging an extension cord with them.
I'm guilty of this too.

Self unplugging when the 50 foot extention cord runs out of slack! Then followed by a 4 letter word when I see the extension cord laying on the driveway

However, I never unplug before starting normally.
 
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Old Dec 21, 2024 | 12:52 PM
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In 45 years of owning vehicles, all having engine block heaters, I never unpluged one of them when starting the engine and letting it warm up. I guess that the main reason for this unplugging notification is to not forget to unplug before leaving and someone suing the car/truck maker because of that.
 
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Old Dec 21, 2024 | 12:55 PM
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its easy to drive off with it still plugged in. ive done it before. thats one reason to unplug before starting
 
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Old Dec 21, 2024 | 05:09 PM
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Only reason I can think of is thermal shock to the element. A warm element suddenly getting hit with icy cold coolant from the other side of the block? Or maybe as others have done, prevent one from driving away still plugged in? Sounds weird to me.
 
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Old Dec 21, 2024 | 09:13 PM
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Originally Posted by acdii
Only reason I can think of is thermal shock to the element. A warm element suddenly getting hit with icy cold coolant from the other side of the block? Or maybe as others have done, prevent one from driving away still plugged in? Sounds weird to me.
That or even a possibility of shock if it breaks. You know, legal concerns more than anything.

"Don't take this medicine if you are allergic to it" kind of thing.
 
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Old Dec 21, 2024 | 09:28 PM
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It can cause cavitation which can burn out your heating element. Same warning comes on other trucks, tractors, etc.
 
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