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Unread 12-22-2013, 11:13 PM   #1
vanwilder
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Wj How long can I leave my factory block heater plugged in?

I have a 01 Grand Cherokee with the factory-block heater (yes it came from Canada and the gauges are in metric too). It doesn't state in the manual how long I can leave it plugged in for. I have a company work truck I use daily, and this last week here in Ohio it didn't get above freezing.
And since I never know when I'll need my jeep I had left it plugged in for 6 days while it sat. Other than maybe burning up the block-heater, will it cause any other damage?

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Unread 12-23-2013, 12:13 AM   #2
bones35
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I've done two days. Never 6 but I Don' t think it will hurt anything. I've also never had a block heater burn out. Hope that helps
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Unread 12-23-2013, 06:44 AM   #3
jfaulk
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When I lived up in Alaska, every now and then I would leave my old K5 blazer plugged in for about a week at a time with no ill effects that I noticed. I've never seen a block heater burned up but I'm sure its possible.
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Unread 12-24-2013, 09:20 AM   #4
Trav1s
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I bought a HD timer for engine block heaters at the local farm and fleet store for $25 that allows me to control on and off times. I sat it to come on three hours before I needed the WJ. It works great and saved on electricity.
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Unread 12-25-2013, 09:57 AM   #5
86cj74.2L
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When I left my cummins plugged in for more than a day it created a air pocket in the head that you herd pushing around for a few min after startup.

The heater would sizzle when plugged in. That is my indication its that its on and working. Now if needed, I just plug in a few hours before........

The trucks heater is 750w
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Unread 12-26-2013, 01:42 PM   #6
EmersonHart13
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I run mine for about 3 hours before startup thanks to a nice HD timer. Was 10-15 bucks at Menards.
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Unread 12-26-2013, 07:15 PM   #7
madZJ
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Plug it in about three hours before starting, there's no need to have it plugged in all the time. I have an autostart and i fire it up about 15 minutes before I want to leave, and she's nice and warm. The previous owner or the dealer installed a block heater but I never use it. If one was going to buy a block heater I would recommend a tank style over a freeze plug style.
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Unread 12-26-2013, 08:49 PM   #8
jbaldry
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How hot does it get your block? Enough for it not to be pinned on the coldest temp? I have one by the way but when I used it it didn't seem to do much. It was also only 20 out
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Unread 12-26-2013, 09:08 PM   #9
86cj74.2L
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My cummins will see 120 after 3hr
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Unread 12-28-2013, 09:51 PM   #10
n7mog
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engine block heater or....

I'm a fan of engine block heaters in a freeze plug hole. First choice, however, is a battery blanket usually only 80W. If the battery is warm, it will provide the cranking amps to turn even a cold engine over, but if the battery is cold the capacity will be greatly reduced and may not even be able to crank a warm engine well enough. If a vehicle is not used for a few days in real cold weather, a three stage trickle charger about 1 to 1.5 A is the #2 item I would use after the battery blanket. Surprising how much the standby electronics suck capacity from the battery when it's really cold out. Last would be the engine block heater. I would rarely use a tank or radiator hose heater, they just don't trip my trigger as they provide for more leak points, IMHO. Engine rebuilds that I have done always get a block heater in a freeze plug hole. Heck, I've even put two in big blocks in the past during rebuilds. YMMV.
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Unread 12-28-2013, 10:47 PM   #11
jbaldry
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Or you get a Die Hard Platinum with 930 Cold Cranking Amps
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Unread 12-30-2013, 12:41 PM   #12
n7mog
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Buying a new battery or bigger battery is fine, but you miss my point. At a reduced temperature any battery loses a quantity of it's capability. If you bother the research this, you will understand my comments. I also stated that you can make your own decisions. I enjoy forums that allow differences of opinion and viewpoints. My opinions have been expressed, I hope that you can accept them as solutions that I have embraced.
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