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Block Heater

5K views 26 replies 12 participants last post by  oldrebuiltdodge 
#1 ·
In cold weather, how long can you leave the block heater plugged in? My neighbor said I shouldn't leave it plugged in for more than 5 hours on these IDI engines. I'd like to leave it plugged in over night instead of getting up early and plugging it in at 5 or 6 am. thank you.
 
#3 ·
You can leave it plugged in 24/7/365 and the only thing you are going to hurt is you wallet when you go to pay the electric bill.

But in the long run it doesn't do any good to leave it plugged in much longer than 3-4 hours before you need the truck. Just get a heavy duty 15-20 amp timer and set it for that long before you need your truck.

Now if you are not paying the electric bill then by all means plug it in when you get home and just leave it plugged in.
 
#4 ·
When my pickup was my daily driver I had the heater on a 1500 watt timer. I found even at 10° below, 2-3 hours of heat was enough for easy quick starts. What was your neighbor's reason for no more than 5 hours? Like posted, doesn't hurt a thing.
 
#5 ·
Have you read the owner's manual &/or diesel brochure? The '92 edition says "...the heater should be plugged in at least 3 hours prior to starting. The use of the heater for longer periods of time will not cause the engine to exceed the thermostat setting." That implies that the heater has an internal t'stat which will cause it to cycle off once it reaches its design temperature. It's a 1KW heater, which means it draws 9.1 Amps @110VAC.
 
#6 ·
There is no internal thermostat on the block heaters on these trucks.

It is just a rod that is inserted into the coolant passage. It wont really get the coolant very hot just from it's design and no circulation of the coolant. That along with trying to heat up a huge block of cast iron.
 
#7 ·
There is no internal thermostat on the block heaters on these trucks. It is just a rod that is inserted into the coolant passage. It wont really get the coolant very hot just from it's design and no circulation of the coolant. That along with trying to heat up a huge block of cast iron.
Right, and with that said, there's no way that small 900-1000 watt element is going to heat a block anywhere near engine operating temp if the outside temp is cold enough to require plugging it in.
 
#8 ·
Thanks fellows*for all the replies, Just bought this 88 super duty, first diesel. Was told hard to start in cold weather so just cking things out. Can't remember why neighbor said not more than 5 hrs. but next time I see him I'll ask again and let you know. I also couldn't think of a reason why because of all the trucks in colder areas then where I live. It might get down into the teens but not very often. Thanks again Bill
 
#9 ·
Get the glow plug system working properly and if it just gets down into the teens you will never need to fire up the block heater.
 
#13 ·
Heck, I plug in when the temps are even +30*F when its someone elses dime and I will leave it plugged in all night...like at a hotel.

When its my own dime I plug in when its +20*F sometimes, depends on if its windy since that wind will be pulling heat away.

I have read 80% of engine wear occurs during initial cold start, that may be an exaggeration but even if its 50% then its still worth it to me to plug in a couple hours.
 
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#14 ·
When its my own dime I plug in when its +20*F sometimes, depends on if its windy since that wind will be pulling heat away.
Right, and quite a few "keyboard mechanics" have argued wind chill only applies to living flesh. Park your truck on a 10° day in the sun with no wind and the cab will be way warmer than the same temp on a windy day. Even with a dark color the cold wind sucks the heat right out of the sheet metal.
 
#17 ·
When its my own dime I plug in when its +20*F sometimes, depends on if its windy since that wind will be pulling heat away.
Right, and quite a few "keyboard mechanics" have argued wind chill only applies to living flesh. Park your truck on a 10° day in the sun with no wind and the cab will be way warmer than the same temp on a windy day. Even with a dark color the cold wind sucks the heat right out of the sheet metal.
A good rule to live by:
Never argue with a man from Wyoming about wind !

?
 
#15 ·
The wind does cool things off a lot faster but metal can not be cooled any lower than the ambient temperature that surrounds it.

The effect of wind chill is to increase the rate of heat loss and reduce any warmer objects to the ambient temperature more quickly. It cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity.

I do agree that a vehicle parked in the sun on a 10 degree day will feel warmer than the outside temperature and if a wind kicks up it is going to cool off but it will go no lower than what the temperature is outside of the vehicle. So it goes from lets say 50 degrees inside temperature down to 10 degrees as the wind blows across the metal of the vehicle. But the inside temperature will get no lower than 10 degrees.
 
#20 ·
The effect of wind chill is to increase the rate of heat loss and reduce any warmer objects to the ambient temperature more quickly. It cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity.

Actually... wind moving across moisture evaporates that moisture which removes thermal units by the heat of vaporization (energy required for the phase shift from liquid to gas) - that’s the principle behind evaporative coolers, how perspiration cools a body, etc.






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#16 ·
I would take Bugmans advice and get a timer/tune up the the glow plug system. If you are paying the electric bill a timer will pay for itself in month or so. I usually plug in when it gets too below freezing, and have the timer come on 2-3 hours before I want to leave. I may leave it on all night if it is down to -20 or lower, but usually even 2-3 hours works fine at that temp. They make extension cords that have a clear ends that light up when you have power going through the cord. They work great for making sure the outlet/timer is getting power to your truck. Some drape the cord over the drivers side mirror to help remember they are plugged in. If the truck is cold when I plug in my block heater I can hear it working if I put my head down by the driver side tire if I don't have a lighted cord. Make sure you batteries and glow plug system is in good working order in the fall. Remember you can't always plug in when you are away from home.
DENNY
 
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#18 ·
+1 on the cord ends that light up when powered.

Also be sure to get the proper gauge extension cord. That heater draws some amps.
 
#22 ·
Several ways to compute Wind Chill Factor some do not use humidity in the formula. However, Bugman is correct, you will not reduce temperature below ambient. The Wind Chill Factor charts came about in Artic exploration as a way to prevent frostbite.
DENNY
 
#27 ·
When I was moving to Kansas, I was told that there was nothing between Kansas, and the North Pole, but a barb wire fence, and it leans south. I've been to Wyoming, and when you can get passed by an empty Coke can @ 60 mph...well that's more wind than I ever saw anywhere in Kansas.
 
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