A Suzuki is parked in the snow and connected to a power outlet to power a diesel block heater.

Using a Diesel Block Heater

Gasoline and diesel engines convert fuel into chemical energy, which then supplies mechanical energy to power a vehicle. Diesel engines differ from gasoline engines, as they don’t have spark plugs and they require a higher compression ratio to operate. Because diesel engines also demand higher temperatures to fire fuel, they’re more difficult to start in cold weather. That’s where a diesel block heater proves its worth on frigid winter mornings.

An engine block heater is useful to countless motorists who operate vehicles in climates where temperatures regularly fall far below the freezing mark. These heaters warm your engine to improve both the odds and the ease of starting it in cold weather. Not only is a block heater useful for starting your vehicle, but it also helps reduce wear and tear on the engine, mitigating excess fuel consumption and lowering harmful emissions. It also has the benefit of heating the cabin faster! Here’s a look at the two main types of diesel block heaters.

Freeze-Plug Diesel Block Heater

The way an engine block heater works varies somewhat, depending on the type. For a freeze-plug-type block heater, the heating element replaces the freeze plug located on the bottom of the engine block, heating the coolant at that location. The top of the plug usually connects to a supplied 6-foot cord, which then plugs directly into a household outlet. It is extremely important to obtain an accurate fit for your vehicle when purchasing one, otherwise coolant could leak after installation.Parked cars in the snow

You might also control the heater at the outlet with a timer, activating it about two hours before you’re ready to leave in the morning. That way, you aren’t using excess energy to warm the coolant.

Engine-Coolant Diesel Block Heater

The other option is an engine coolant heater. Instead of connecting to the bottom of the engine, this type of block heater connects to a radiator hose. Like a freeze-plug-type block heater, a coolant heater must match the make and model of your vehicle. Some find coolant heaters easier to install and maintain.

It’s important to inspect both types of heaters regularly to ensure that there isn’t coolant loss. If there is, top off the coolant and ensure the heater fits properly. Make this a part of your routine winter vehicle inspection, which also includes the battery, oil, lights, wipers, brakes and tires.

Check out all the heating & cooling systems parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on diesel block heaters, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Wikimedia Commons.

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Matthew C. Keegan

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1 Comment

  • Larry Giacobbo

    March 13, 2018 at 11:08 AM


    An oil pan heater is great for diesel engines as well as a block heater.


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