How to Install Engine Block Heater


There are few things that a driver dreads more than starting a car in the wintertime. Low temperatures can cause engine trouble, but there’s one ingenious component that can help you avoid it – an engine block heater.

In today’s article, I’m going to explain what this thing is and how you can install it. It’s simpler than it sounds and could spare you heaps of frustration. Do not skip this one!

What’s an Engine Block Heater?

A block heater is a component that helps the car fire up smoothly in low temperatures. This little device heats the engine and the fluids that are inside it. Once warmed up, the motor oil is able to flow through the engine efficiently, reducing the time needed to achieve working temperature.

The construction of a block heater is straightforward. It only has two parts: a power cord and a heating element. The latter is placed on the engine block, and it gets heated up by receiving power from the cord. 

The key thing you need to know is that there are several types of the block heaters. They are:

  • Freeze plug heaters
  • Drain plug heaters
  • In-line heaters
  • Cartridge heaters
  • Oil Pan heaters

All of them work on different principles and require a different installation method. In the upcoming paragraphs, I’m going to explain how to install each one individually. Let’s get into it.

Installing freeze plug heaters

This type of block heater is installed on the engine block in the place of a freeze plug (hence the name). Freeze plugs are located on the back of the engine and are shaped like round cups. If you don’t know what they are, Google Images can help you out.

The freeze plug heater is considered to be one of the most efficient, but it’s not the easiest to install. No worries, I’ll explain the installation process step by step. It looks something like this:

  1. Drain the cooling system. Make sure that the radiator is completely empty of fluid. You can do this by using the drain plug that can be found on most radiators. In case you don’t have it, remove the lower hose clamp and pull the hose so that the coolant can flow out. Don’t forget to put a pan under the radiator so that it collects the fluid.
  2. Remove the freeze plug. Before you remove just any freeze plug, check the instruction manual that came with your block heater. For some models, you’ll have to remove a specific plug.
  3. Clean out the hole to rid it of sharp edges, paint, or grime.
  4. Take the O-ring off your block heater and place it into the freeze plug hole.
  5. Insert the block heater and make sure that it isn’t touching any element inside the block.
  6. Take the heater out and mark the position.
  7. Reinsert the O-ring and put the heater into the hole.
  8. Start refilling the engine with the coolant liquid and check if it leaks somewhere.
  9. Once everything is set up, connect the heater to the car’s electrical system.
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Black Truck in the snow needs an Engine Block Heater

Installing drain plug heaters

Drain plug heaters work on the same principle as their freeze plug counterparts. However, the installation process is quite different. As the name implies, drain plug heaters are placed in the block’s drain plug.

The process looks like this:

  1. Drain the coolant from the engine, but you don’t have to drain the radiator. Lower the level of coolant enough so that you can open the drain plug without the fluid pouring out.
  2. Remove the drain plug and put it in a place where you can find it when you need it again.
  3. Place some sealing tape on the threads of the heater and screw it in where you removed the plug. Follow the instruction manual while doing this.
  4. Refill the engine with the coolant while checking for leaks.
  5. Plug the cord into the heater and connect it to the electrical system of the car.

Installing in-line heaters

In-line heaters are one of the oldest around. They still work well, so there’s no reason not to use them. An in-line heater is a great option for those who cannot fit other kinds of block heaters on the engine.

The in-line heater is really simple to install. It can be placed pretty much anywhere you want on the circulatory system of the coolant. Here’s an example of how you can do it:

  1. Locate the output of the radiator. Again, it doesn’t have to be this particular location, but I’m using it as an example.
  2. Cut a piece of any coolant hose. Insert one side of the hose into the input and the other in the output of the block heater.
  3. As the coolant passes through the heater, it’ll get warmed up.
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Installing cartridge heaters

Cartridge heaters are even easier to install than in-line heaters. However, there’s a trick – your car’s engine has to be compatible with them. If it’s not designed to support cartridge heaters, you’ll have to opt for some other type.

Cartridge heaters aren’t the cheapest, but they spare you the potential leakage that comes with, say, freeze and drain heaters.

Here’s how you do it:

  1. Find the special metal housing for the heater. It should be located close to the coolant chamber, on the side of the engine head. 
  2. Once you’ve found it, simply slide the cartridge into the slot and clip it to a bracket.

Installing oil pan heaters

Contrary to the misleading name, oil pan heaters don’t just heat up oil pans. They are incredibly versatile, and you can use them on any part of your engine. 

Oil pan heaters have a heating element encased inside a plastic pad which can be stuck on a metal surface. People most commonly place it on – you guessed it – the engine oil pan. But, as I said, you can stick it elsewhere, for example, on a transmission oil pan.

The great thing about these heaters is that you can use more than one on the same car. If you choose to do so, it is advisable to connect them to separate power cords.

Without further ado, let’s take a look at the installation process:

  1. Choose the area of the engine where you want to place the heater. Clean it thoroughly using an alcohol-based cleaner. The metal surface has to be free of greasy and dirty bits.
  2. Remove the backing paper and place the sticky side of the heater on your chosen location, preferably the oil pan.
  3. To prevent any moisture from creeping in, apply a layer of silicone gasket market around the heater.
  4. Connect the cord to the car’s electrical system as with any other heater.
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There you have it, folks, my quick and easy guide to installing block heaters. Before I go, I’d like to leave you with some final words of advice.

 It’s vital not to rush when trying to decide which block heater to buy. Take your time to get acquainted with every type, and then figure out which one would work best for your car’s engine. A mismatch would give you more headaches than cold weather itself.

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