Block Heater - OK to leave plugged in?

ShaqDiesel · **Posted:** Mon Nov 23, 2015 12:21 am

Quick question: Is it ok to leave the block heater on for days at a time? Is there a maximum amount of time you should leave it plugged in?

Hexus · **Posted:** Mon Nov 23, 2015 12:38 am

Other than sucking about 40W from your house, or wherever you have it plugged in, there's no risk of damage to your vehicle from the block heater.

You may shorten the longevity of the heater using it that long, think of a light bulb, but no harm will come to your vehicle.

papaindigo · **Posted:** Mon Nov 23, 2015 9:36 am

Pretty much what Hexus says. It's essentially identical to the heater in an electric hot water heater and continuous usage will cut into it's life. It only pulls 3-5 amps IIRC so your best bet is to get a decent household timer, I'd recommend a digital one with a backup battery so it doesn't "forget" settings if power goes off, set to come on about 1.5hrs before you normally use the vehicle.

It does make starting easier and cabin warm-up much quicker once temps get to like +20F or below although some report ok starting without the heater at much lower temps.

Mountainman · **Posted:** Mon Nov 23, 2015 11:45 am

I would only have the block heater on when you're awake enough to smell or see smoke. Every cord I've seen was cracked significantly, and I don't want to take the chance of setting my house on fire when I'm asleep. :dead:

synthetic-oil · **Joined:** Tue Sep 24, 2013 8:03 pm **Posts:** 140

I built me a thermostatic electrical plug for my heater.

thermorex · **Posted:** Mon Nov 23, 2015 8:57 pm

Hexus wrote:

Other than sucking about 40W from your house, or wherever you have it plugged in, there's no risk of damage to your vehicle from the block heater.

You may shorten the longevity of the heater using it that long, think of a light bulb, but no harm will come to your vehicle.

I concur, with exception of being 450w from what I remember... In other words you waste your money as it needs only 2-3 hours plug in before you drive it. Best thing going is to get some oil pad warmer which sticks on the oil pan (and transmission if you choose) and connect it to the same plug as the block heater. You'll be well within the 15 amps a common residential outlet will handle.

KCKJ · **Posted:** Tue Nov 24, 2015 10:42 pm

I agree that I wouldn't plug it in unless I was around. My dad has told me stories about snowplows going up in flames due to block heaters. Always kind of scared me. Enough to make me cautious. If my jeep goes up in smoke, im out a jeep and probably a garage and house too.

Hexus · **Posted:** Wed Nov 25, 2015 8:40 am

Why would you plug it in when it was inside your garage anyways?

Even a detached garage would keep enough cold off to nearly make it a moot point.

thermorex · **Posted:** Wed Nov 25, 2015 11:06 am

I also plug the crd while is in the garage. And I have the garage attached, and the coldest I had in the garage was about 37F when outside were - 5F. I see 2 main benefits in doing this: temperature comfort when driving right away and a better oil fluidity, since the residual coolant heat transfers to the oil. Is this a reason to warrant using the block heater all the time in winter? For me yes, for wear and tear on the engine probably minimum to medium. The benefit in having it plugged in more than couple hours is the residual heat going into the engine oil and transmission. I usually hop on the highway within half a mile, and I like to be able to lock the torque converter right away. I believe the torque converter locks only when Trans temp is over 80F, if memory serves right.

thermorex · **Posted:** Wed Nov 25, 2015 11:12 am

KCKJ wrote:

I agree that I wouldn't plug it in unless I was around. My dad has told me stories about snowplows going up in flames due to block heaters. Always kind of scared me. Enough to make me cautious. If my jeep goes up in smoke, im out a jeep and probably a garage and house too.

If you're concerned about setting something on fire, inspect the heater cable for cracks and replace if necessary. Kat has the heater cable for about 30-ish bucks on Amazon.com. Then you can add a smoke detector in the garage. If you have a big house and you're worried you won't hear the alarm, there are "smart" detectors that you connect to your Wi-Fi and alarms your smartphone. Or you can use the wired detectors that should be installed through your house so when is a smoke alarm, all your detectors will start screaming.

papaindigo · **Posted:** Wed Nov 25, 2015 11:14 am

I would certainly agree that insulation can crack but how likely it will do so in a manner to cause a short, without tripping the supply line circuit breaker, AND start a fire is a diesel fueled vehicle is debatable. In any case the only "apparent" cracking I've seen on the half dozen or so CRDs I've touched has been directly correlated with vehicles that had been driven for some time with the heater cord in its original wadded up at the factory and zip tied to the dipstick tube positions. Even then the cracking was in the secondary external rubber that holds the 3 wires together and not in the actual wire insulation.

thermorex · **Posted:** Wed Nov 25, 2015 11:16 am

papaindigo wrote:

I would certainly agree that insulation can crack but how likely it will do so in a manner to cause a short, without tripping the supply line circuit breaker, AND start a fire is a diesel fueled vehicle is debatable. In any case the only "apparent" cracking I've seen on the half dozen or so CRDs I've touched has been directly correlated with vehicles that had been driven for some time with the heater cord in its original wadded up at the factory and zip tied to the dipstick tube positions. Even then the cracking was in the secondary external rubber that holds the 3 wires together and not in the actual wire insulation.

That is correct, and the cracks are very likely correlated to a fatigue of the insulation of the cable due to engine heat. More than likely the fuse will blow up.

dirtmover · **Posted:** Wed Nov 25, 2015 11:33 am

thermorex wrote:

I also plug the crd while is in the garage. And I have the garage attached, and the coldest I had in the garage was about 37F when outside were - 5F.

I have a similar experience. A jug of water left in my attached garage will start to freeze when the outside temperature reaches around 0F. When the overnight temperature dips down to around -20F an hour with the block heater on definitely helps.

Every year we see a number of reports of house fires started by the use of block heaters. Be sure to inspect the cable, connections and any extension cables you're using on a regular basis.

robert.janowski · **Joined:** Sat Nov 28, 2015 9:14 pm **Posts:** 10

I've used block heaters for years. Never had a problem. Plug it in when i get home and unplug it when its time to head to work. (When over night temps drop below 40 degrees ) A block heater is not designed to warm up a cold motor. It is designed to maintain warmth once the vehicle is parked after being ran.

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olypopper · **Posted:** Sun Nov 29, 2015 3:54 am

My vehicles get plugged in at 2100 each night and are plugged in from October until sometime in April.

An average number to remember is 10 degrees per hour........for every hour your engine is plugged in, the temp will rise inside the block approx 10 degrees. This is very important especially if you live somewhere it actually gets cold. If it's -40 out and your rig is cold soaked......yep, your engine has achieved a whopping -30 temp. Not too many diesels going to be happy about that.

Another item that can add life to your engine is adding an oil pan heating pad. This will aid in warmup time as well as get the oil flowing if it's really on the cool side.

thermorex · **Posted:** Mon Nov 30, 2015 3:54 pm

olypopper wrote:

My vehicles get plugged in at 2100 each night and are plugged in from October until sometime in April.

An average number to remember is 10 degrees per hour........for every hour your engine is plugged in, the temp will rise inside the block approx 10 degrees. This is very important especially if you live somewhere it actually gets cold. If it's -40 out and your rig is cold soaked......yep, your engine has achieved a whopping -30 temp. Not too many diesels going to be happy about that.

Another item that can add life to your engine is adding an oil pan heating pad. This will aid in warmup time as well as get the oil flowing if it's really on the cool side.

I was thinking also to add an oil heater pad. Do you have a specific size you're using. I would have to take the armor out to measure the pan, which I hope you can help me avoid [WINKING FACE]

rjmaype · **Posted:** Mon Nov 30, 2015 11:15 pm

Before you add the oil pan heater, add a trickle charger to the battery on the same timer as the block heater.

The efficiency of the battery drops dramatically in low temps.

Just like farmers who placed a light bulb near the battery on a tractor, getting the battery up to normal temp makes a hugh difference.

thermorex · **Posted:** Thu Dec 03, 2015 1:35 pm

I have that already. It's separate from the heater as I leave it in in the summer sometimes, when I don't drive the crd for few days. But I agree with you.

olypopper · **Posted:** Tue Dec 08, 2015 6:14 pm

thermorex wrote:

olypopper wrote:

My vehicles get plugged in at 2100 each night and are plugged in from October until sometime in April.

An average number to remember is 10 degrees per hour........for every hour your engine is plugged in, the temp will rise inside the block approx 10 degrees. This is very important especially if you live somewhere it actually gets cold. If it's -40 out and your rig is cold soaked......yep, your engine has achieved a whopping -30 temp. Not too many diesels going to be happy about that.

Another item that can add life to your engine is adding an oil pan heating pad. This will aid in warmup time as well as get the oil flowing if it's really on the cool side.

I was thinking also to add an oil heater pad. Do you have a specific size you're using. I would have to take the armor out to measure the pan, which I hope you can help me avoid [WINKING FACE]

I use the Wolverine brand pads and the GP100 (100 watt and gets around 220 degrees plugged in) and it's size is 4"x5". I use red high temp RTV to glue it to the pan.......I install a 75 watt on the trans if you are really serious about your cold weather play!

thermorex · **Posted:** Tue Dec 08, 2015 6:42 pm

olypopper wrote:

thermorex wrote:

olypopper wrote:

My vehicles get plugged in at 2100 each night and are plugged in from October until sometime in April.

An average number to remember is 10 degrees per hour........for every hour your engine is plugged in, the temp will rise inside the block approx 10 degrees. This is very important especially if you live somewhere it actually gets cold. If it's -40 out and your rig is cold soaked......yep, your engine has achieved a whopping -30 temp. Not too many diesels going to be happy about that.

Another item that can add life to your engine is adding an oil pan heating pad. This will aid in warmup time as well as get the oil flowing if it's really on the cool side.

I was thinking also to add an oil heater pad. Do you have a specific size you're using. I would have to take the armor out to measure the pan, which I hope you can help me avoid [WINKING FACE]

I use the Wolverine brand pads and the GP100 (100 watt and gets around 220 degrees plugged in) and it's size is 4"x5". I use red high temp RTV to glue it to the pan.......I install a 75 watt on the trans if you are really serious about your cold weather play!

Lol. Thanks for the reply. I plan on doing a combo with oil and trans heaters all together with the block heater. So I am very serious as you can see :lol:

Block Heater - OK to leave plugged in?

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