How fast does a block heater heat

[Snagglefoot]

Looks like today was the last cold morning for a while. It was -17 F. I decided to plug the block heater in and see how fast it warmed the engine. I decided to use the oil filter as the location of the temperature measurement, using a laser point infrared temp gun. The car was a 2005 Ford Taurus with a freeze plug style block heater.

Starting at -17 F the temps where as follows after each one hour of heating with the block heater :

1 hr. -6 F
2 hrs. 11 F
3 hrs. 31 F
4 hrs. 36 F

So after 3 hrs the temp rose to 31 F. The ambient temp was still about -15. During the fourth hour there was only a 5 degree increase to 36 F, a diminishing rate of increase, probably due to the heat transfer into the cold air. ( and also radiating to the surrounding surfaces). I don't know how many watts the heater is.

So, if core plug type block heaters are your thing, I would think it would be worthwhile to invest in a timer to get a good three hours of heating prior to starting the vehicle. I would also imagine a pan heater would really help with the oil temperature if you preferred that. As usual. YRMV. Thanks for reading.

 

[Linctex]

When I lived in North Dakota, at -35*F ..... one solid hour on the timer was plenty of heat for the block heater and oil pan.

I think the block heater was 800 watts (or maybe 500?) and the oil pan heater was 80-100 watts or so. Instant starts every time.

 

[Colt45ws]

Oil filter is too far off the engine to be a good readout, I think.
I found on my car it was about 5 hours to reach maximum, about a 90F rise above ambient in relatively still air. Its a 400W core plug type. I use the OBD2 Readout of the temp sensor screwed into the back of the left cylinder head. Im less worried about just getting it started vs having cab heat available ASAP so I want the maximum temperature that it will give me.
So I stopped using a timer. I come home, and plug it in. It heats it all night. 5kWh every night, or like $0.7. I'd likely burn that much in fuel if I idled it to warm.

 

[carviewsonic]

I have a timer on our car and my work truck, set for four hours before morning start-up. Looks like not much heat gain after that, and I read somewhere that after six hours there is no more heat gain at all.

 

[tony1679]

Originally Posted by Colt45ws
5kWh every night, or like $0.7. I'd likely burn that much in fuel if I idled it to warm.
This is something I wouldn't have thought of. Interesting. Not that I need a heater in OK, but is an interesting argument for someone to use one up North...

 

[billt460]

Back in the 70's when I was living in Illinois, I had a 1,500 Watt tank type block heater on my 70 Nova SS 396, similar to the model in the link below. It was a bear to start in the cold weather. It drew water in from the bottom of the radiator, heated it, then moved it up through the heater core, heads, and engine block. It worked very fast!

When I first installed it I left it on for 3 hours. And when I placed my hand against the front of the cylinder heads, they were HOT to the touch. I had it on a timer, and in below zero weather when I ran it for an hour, I had heat out of the car within a minute or 2 of starting it, and the windows would start to defrost immediately. The engine spun over like it was Summer.

The biggest advantage was how fast it worked. The disadvantage was you had to remove your drain cock to install it. (I ran a tee connection so I could still drain my coolant). And you had to splice it into the heater hoses. And you had to be sure to have your heater control turned all the way on to full "HOT", so the coolant could circulate through the system. But it sure did the job.

I'm not so sure it would be an easy install on today's modern vehicles. With some of them it's an adventure to simply find the heater hoses.

https://www.zoro.com/kats-circulati...UNt8qSvgbE435IH3UGI_kGFBKrEaAhqEEALw_wcB

 

[demarpaint]

I have a block heater and oil pan heater on my Rubicon. The oil pan heater is the hands down winner for easier cold weather starts. They're easy enough to install, and since they're on the lowest part of the engine and heat rises it makes sense that they work better than warming the coolant for extreme cold starts. IMO the perfect setup is to have both. The block heater helps get the heater and defroster working a little faster, win win. I also have a transmission pan heater, which is nice because it allows the transmission to lock up the torque converter in extreme cold much sooner than it normally would.