what does the Engine Block heater on Diesels actually do. we have plugged it in when it has been around 20 and sometimes just recently it has been around 24 and it has not made a difference.
but what does i do when you plug it in?

small resistors on the sides of the block- supposed to keep the block a little warmer than ambient air temp... Mine suck too! i dont notice a difference. Actually harder to start when I use my warmers... Like it fires up, then that cold fuel hits it... and then its cranking time to get the flood out!! did it today at 11am.

It takes 2 or three hours to heat the oil. They are usually under 1000 watts. Their purpose is to warm the oil enough to be more fluid. A regular motor oil gets so thick its like molasses.
In a synthetic oil you wouldn't need it as much.


I've only used my block heater a couple times when it was new. Discovered it doesn't help much so I've never used it again. I do run synthetic.

OOps. The block heater on a Dodge is mounted mid engine on the starboard side just behind the oil filter. It doesn't appear to heat the oil at all.

the block heaters actually go into the freeze plug locations on most diesel applications to help with cold start in subzero conditions,in temps above freezing you will not see much of a difference.

I had one in the 5.4 gasser in the expedition. (bought from PA)

Like Stan said, they replace one of the freeze plugs in the coolant galley. They heat the coolant. The only reason I use mine is so the heater will warm up quicker.

I currently have 2 Dodges. 1 is a 96 with a mechanical engine (work truck) that has the pump turned up just a bit, If I don't plug this one in, it will spit and sputter for a few seconds and then level off and idle like a champ. But plugged in, she busts right off and never misses a beat.

My personal truck is an '03. When I don't plug her in, she clatters like crazy for a second or 2, and the heater takes FOR EVER to warm up. When I plug her in, she cranks up like she does in the summer.

I guess even though the block heater is actually heating the coolant, some of that heat radiates to the oil pan, keep the oil some what warm also....explains the chattering

Thanks for the location Allison1, the parts guy at the Dodge house couldn't even tell me where the block heater connection was.

thanks for the help. like i said we used to plug it in. but ow we dont worry about it. you could tell when we were pulling a trailer or not on cold mornings. because it would take about 2000 RPMs to get it moving pulling a trailer when it was not pluged in.

This was designed for start ups. Plug it in before you go to bed. It would crank right up!!!!

I still have a Powerstroke with one.


P.S. I am old enough to drive on my own!!!

My glow plug relay went out on my '97 Power Stroke (repaired now) and without plugging in the block heater in it would take 5 to 10 minutes to get it cranked up. With the block heater it fires right up.

I haven't got a clue Justin!

my dodge will start fine on cold mornings without the block heater plugged in all night. If I plug it in, it starts- then stumbles into a "flood" condition.. and its a biotch to start then!