Coolant Funnel- How to Use and Buying Guide?

A coolant funnel lets you refill a car radiator easily and without spilling coolant. You can also use it to burp the cooling system. More about the tool here.

An example of coolant funnel kit
An example of coolant funnel kit

A coolant funnel is a handy tool when adding coolant or flushing your car cooling system. Using it makes the process easy and mess-free, even when the refill cap is located in a tricky position. In this post, I will cover these topics: what is a coolant funnel, why you need it, and finally, step-by-step instructions on how to use a typical coolant funnel. So let’s get started! What do you know about this coolant filler funnel?

What is a Coolant Funnel?

A coolant funnel is a type of spill-proof radiator funnel used to refill coolant. Being a no spill funnel, it helps you to transfer coolant into your car, easily, conveniently, and without creating a mess. You can also call it an engine coolant funnel, coolant refill funnel, or radiator filling funnel.

A coolant funnel looks like an ordinary funnel, but includes features to make it more versatile and convenient to use. It has a larger space for coolant, for example, and a stopper to seal it when and prevent spills. Many car owners also use it as a coolant bleeding funnel to remove trapped air from the cooling system.  

Why You Should Get a Coolant Funnel

There are several benefits of using a coolant fill funnel. Driving with a low coolant level is dangerous and can lead to your engine overheating and getting damaged. So you want to make sure the reservoir is always filled.

But adding coolant can be tricky. It often leads to spills, even when using an ordinary funnel, causing loss of coolant and bad messes. You will also have air pockets trapped inside the cooling system.

Some cars also have the radiator or coolant reservoir cap located in awkward positions, making it hard to pour coolant into the radiator or expansion tank. A coolant or radiator filling funnel saves you the trouble.

Coolant funnels are inexpensive, easy to use, and come with adapters for different kinds of car cooling systems. In short, using a radiator funnel allows you to pour coolant quickly, easily, cleanly and safely without spillage.

This is a typical coolant funnel kit
This is a typical coolant funnel kit

Coolant Funnel Kit

There are many different cars and trucks today from different auto makers. These will have their coolant refill openings in different places. The coolant caps, too, will be different sizes and configurations. The radiator funnel must support these different cars. Auto tool makers, therefore, avail the funnel as a kit.

A coolant funnel kit is just a coolant funnel with attachments to make it compatible with the cooling systems of different car makes. The attachments usually include caps, extensions, and adapters. Here is a list of what you will normally find in a typical coolant filling funnel kit.

  • No-spill radiator funnel with a lid
  • Stopper
  • Extensions
  • Adapters
  • caps

Coolant Funnel

This is the coolant filler funnel itself: a large, plastic funnel with high sides and a lid. The large funnel allows you to pour coolant without it spilling. It’s usually clear plastic so you can see the coolant level and avoid overfills.

Coolant Funnel Stopper

The stopper is plastic piece that you insert into the funnel’s bottom opening. It seals the funnel when you have finished adding coolant. It helps prevent spills when you lift the funnel, making it a spill-free funnel.

Coolant funnel Extensions

These are attachments to use with the coolant funnel. They consist of straight pieces and angled pieces. Straight pieces extend the funnel’s reach. The angled pieces enable you to use the funnel with radiator openings that can only be accessed from the side.

Coolant Funnel Adapters

The adapters are among the most crucial components of the coolant filling kit. They attach to an extension on one end, while the other end goes into the radiator or coolant reservoir cap opening. The bottom has a rubber gasket to seal of the connection.

Coolant Funnel Caps

The funnel caps replace the radiator or coolant reservoir caps. They help attach the funnel and its attachments firmly to the radiator or coolant tank so it doesn’t move about. Coolant funnel caps can be metal or plastic, threaded or unthreaded.

How to use a coolant funnel correctly
How to use a coolant funnel correctly

How to Use a Coolant Funnel Kit

A coolant funnel kit comes in useful when doing a coolant flush. In the event of a coolant leak, you also want to have it with you. Radiator funnel kits also save you from spilling precious coolant all over your car and getting filthy in the process. You also get everything done quickly and without trapping air in the cooling system.

Here is a tutorial on how to use a coolant funnel kit to add coolant into your cars cooling system. You will also be using the funnel to bleed air out of the system.

Things you will need:

  • Coolant
  • Coolant funnel kit
  • Rag to wipe coolant off the cap opening

Note: before using the radiator fill kit, make sure the car is off and the engine is completely cool.

Step 1: Attach Funnel Adapter to Cap

  • Find the adapter type and size that is compatible with the radiator or coolant reservoir opening of your car.
  • The conventional coolant radiator funnel kit will normally come with about 5 different adapters.
  • Install the adapter to the right cap from the kit. Tighten the two attachments to make a leak-free connection.

Step 2: Install Coolant Funnel Adapter

  • Locate and remove the radiator cap (or coolant reservoir cap in some cars).
  • Install the coolant funnel adapter to the radiator opening using the cap.
  • Twist the cap to make a leak-free connection. The adapter comes with a runner seal to ensure that.
  • You’re now ready to insert the extension if necessary.
  • Only use an extension is the radiator or reservoir is set deep I the engine bay or at an angle.

Step 3:  Insert Coolant Funnel Extension

  • Depending on your car make and model, you may either need a straight or angled extension.
  • Choose, from your funnel kit, the most appropriate extension and attach it to the installed adapter. Ensure a firm and tight connection.

Step 4: Install Coolant Funnel

  • Attach your radiator fill funnel.
  • Pour coolant into the funnel and until the funnel is 1/3 full.
  • Make sure to use a 50/50 antifreeze-water ratio.

Step 5: Burp the Cooling system

  • Get into the car and start the engine. Leave it at idle
  • Turn on the AC to and switch it to hot
  • Wait for the thermostart to open and the engine to start cooling.
  • You should see bubbles of air coming out of the coolant funnel and the level of coolant dropping.
  • Wait for all air to bleed out of the cooling system. This will help to prevent air pockets that lower engine performance.

Step 6: Remove Coolant Funnel

  • Insert the coolant funnel stopper to stop coolant from flowing down.
  • Remove the funnel together with the remaining coolant.
  • Unscrew the funnel cap and remove it together with the adapter.
  • Replace the radiator (or coolant reservoir) cap.
  • Detach the funnel extension and adapter.
  • Clan and store your funnel kit.

As you can clearly see, coolant funnels are easy to use when working on your car’s cooling system. It’s also a lot more convenient and cleaner than ordinary funnels with its spill-proof design. In addition to convenience, the many attachments make radiator funnel kits a lot more versatile and compatible with many different automobiles.

New coolant funnel kit
New coolant funnel kit

Coolant Funnel Kit Price

The coolant funnel is an inexpensive piece of equipment. A complete coolant funnel set or kit generally cost from as low as $25. When buying one, it’s important to consider the kind or number of attachments that it comes with.  This will let you know the kind of vehicle it can be used on.

Radiator funnel kits with fewer attachments will support fewer vehicle types, for example. So it’s more advisable to choose kits that offer a near universal fit, so they can be used in most vehicles. This mostly applies to those who own several car types.

In most cases, a radiator fill kit has about five pieces for each accessory: adapters, caps, and extensions. Be sure to choose those that use quality materials and sturdy construction, too, and clear plastic for coolant visibility. Just as is the case with other auto tools, avoid kits that are too cheap.


Using a coolant filling funnel kit is an easy way to ensure you fill your car cooling system easily and cleanly. It makes the job effective and efficient. The good thing is that can use your spill-proof funnel kit to add coolant as well as burp the system to remove air and ensure a proper fill. Only ensure that you select the right kit for your type of vehicle, and that you know how to use it correctly.

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About Author
Richard Johnson
Richard Johnson

Richard Johnson is a writer and a content marketer who works for hand in hand with Sunbright Automotive Tools. Beforehand, Richard Johnson worked for multiple industries that had helped both small and big businesses to build better brands online through web page contents that productized services.

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