3 prong plug in engine? Why?
 

Hi. Wondering why this would be in my engine? If you look at the 2nd picture, the plug powers goes to the red knob. why?

digi

It's a block heater.

Great! Owner didn't mention that. Thank you!

Yep, its a heater that heats up your coolant. Plug it in on cold nights and your car will warm up alot faster.

Is it necessary for NY winter? How cold does it have to be? Sorry for the newbie questions...

In Brooklyn, it doesn't matter. Someone is going to steal your extension cord anyway.... :D

you'll want to use it

HAH! Yes... I've been looking into security. Maybe a pitbull in the car.

I use mine if it's below about 20F, but my car will normally start without it at 0F. It saves some wear and tear on the engine and you get heat almost immediately.

They really are a nice feature to have or one to add.

You don't NEED it but it will help as long as your engine is still in good condition. I never used it as I had street parking only, always started up even on the coldest days.

Every engine is a little different. Some are unusually friendly, some are unusually finicky, and most are in between. The "in general" answer is

25-30 degrees and warmer: no heater should be necessary as long as your glowplugs work
0-25 degrees (give or take): Heater will help but if you can't practically use it, you probably won't notice a HUGE difference *provided* your battery is strong and your oil doesn't get too thick.
Below 0: it's a good idea to plug in.


Again, these are estimates. 60x engines are thoroughly different than 61x engines for cold starting. Some examples of each will start at negative ten degrees with no extra heat. Some will refuse to start without the plug at fifteen positive if they're not up to snuff.

The Original Block heater quit on her car and I opted for one of these units in the lower rad hose rather than trying to do the block heater instead. I found this to be a better heater than the block heater and way easy to install/ get at. I may put one on my car aswell if/when the block heater in mine goes out. It was cheap too, I think 45 bucks. When she lost hers it was -35 degrees celcius.....so we needed it in a hurry to drive the car up here in the cold.

It's an engine heater but not the original in-the-block heater. It's a lower radiator hose engine heater. There may also be an in-the-block heater above the starter.

Yes, That's correct Kerry. I think the idea with this aftermarket "lower rad hose" type heater is basically the same as a factory blockheater except for the location. The o.e block heater is right in the freeze plug hole in the engine block as you mention and the aftermarket heater in the lower rad hose. I think the coolant in the lower rad hose is heated with an element (same as o/e block heater) and because it is low in the circuit allows for convection heat to travel up the hose and throughout the block, maybe even throughout the rad itself ?.

Like I said before it did a better job keeping the block warm for me up in the cold last winter than the o.e unit that was in there before.
I should mention that since posting previously I have gone through the service records of that particular car and found it to have had a new block heater installed in 2004 and burnt out in 2009. I am not sure what brand of block heater it was that was installed so I really should'nt use the term o.e for my particular circumstance in hindsight. It could have been a cheaper jobber unit put in to replace the original at that time I don't know.The car in question is an 85' model so the original if replaced in 2004 lasted for 19 years.(pretty good)

I was a little cocerned with the element affecting flow of coolant in the lower rad hose for summer operating temps. I kept close watch of the guage this summer and noticed no difference in operating temps.
I think the newer rad hose heater was quicker to heat up the coolant and therefore more efficient.
I noticed my power consumption bills get pretty expensive in the winter when plugging in 2 of these old diesel block heaters. I will definately be using a timer this winter. The lower rad hose unit I expect to perform better/cheaper with a timer since it is quicker to heat as mentioned.