Car Cooling System Pressure Testers – Working and Use

How do you check a car cooling system for leaks? This post will teach you all about cooling system pressure testers; what they do, how to use them, and more.

Cooling system pressure tester
Cooling system pressure tester

Cooling system pressure testers save you the agony of an overheating engine- or even its eventual failure. Find out what these testers do and why you need one for your car or truck. I will also be going over the procedure to use a typical automotive pressure tester. So if you’re looking to keep your engine from overheating, then read on.

What is a Cooling System Pressure Tester?

A cooling system pressure tester is a piece of equipment to check the condition or integrity of your car’s cooling system. Cooling system testers introduce pressure into the system, which then helps to reveal leaks in various places such as the radiator, radiator hoses, and cylinder head gasket.

The standard engine coolant pressure tester comes in the form of a hand air pump and pressure gauge. A hose and connector let you attach the tester to the radiator or coolant reservoir opening. Some testers use shop air (air from an external source such as compressor), but these are not common.

How Cooling System Pressure Testers Work

A car or truck cooling system pressure tester is basically just an air pump with an attachment to direct air into the cooling system. The pump simply pushes air into the cooling system, while an attached gauge measures the amount of pressure going into the system.

Engine cooling system pressure testers comes with a gauge that reads pressure in both psi and Pa. If the pressure is too low, it means there is a leak somewhere in your system. You will need to check each part carefully for coolant leaks, and replace any parts once they found to be damaged.

If no leaks are found, then it’s most likely that there might be a problem with your water pump or other components. It’s always important to fix the problem or you might find yourself having to deal with bigger engine problems- and costly ones too.

A typical cooling system pressure tester kit
A typical cooling system pressure tester kit

The Cooling System Pressure Tester Kit

Some cooling system pressure testers are meant to check the cooling systems of a specific car make or model, while can test a variety of cars and usually come as a kit. A standard cooling system pressure test kit consists of the main tool and a range of adapters to fit different applications. The kit contents include:

Air pump

Pneumatic cooling system pressure testers include a hand-operated pump.  The pump can be different styles but basically consists of a mechanism to take air from the atmosphere and pump it into the cooling system.

Pressure gauge

Being a coolant compression tester, this tool must not exceed the specified pressure limit of the particular cooling system. So it’s normally equipped with a pressure measuring gauge to help you tell how much pressure you’re introducing.

Different Adapters

Cooling system pressure tester adapters come in different designs to fit the radiators and coolant reservoir openings of different cars.

Some kits include additional parts such as coolant filer kit or even a coolant temperature gauge. These kits normally cost you more money but offer higher versatility when checking or servicing the cooling system.

Using a radiator pressure tester
Using a radiator pressure tester

What does a Cooling Pressure Test do?

The purpose of doing a cooling system pressure test is to identify points where coolant is leaking. This helps you to fix leaks before they cause your engine to overheat and fail over time. Let’s see why the cooling system should not be leaking and why a pressure tester comes in handy to ensure that.

Your car’s cooling system is always under pressure when the engine is running. This is desirable. It raises the coolant’s boiling point, which prevents it from turning into vapor. That means the coolant can keep cooling the engine even at higher temperature levels.

But automotive cooling systems can develop leaks. When they do, the pressure drops and coolant boils at lower temperatures. The coolant then cannot cool the engine effectively, which leads to overheating problems.

Leaking also leads to the loss of coolant. A cooling system pressure test is all you need in these situations. You can do the test when you suspect a leak in the cooling system or during a coolant flush. In both cases, the test will help avert many engine problems.

Cooling System Pressure Test Cost

It’s usually necessary to check your car or truck’s cooling system so you’re sure it’s working properly and not leaking pressure or coolant.  Without a radiator cooling system pressure tester, you can only have the test done by a mechanic or at a repair shop. That should cost you some money.

Rates vary depending on the specific region. In most cases, you may need to part with between $30 and $50. If you own and know how to use a coolant pressure tester, that’s the amount you will be saving even time your engine shows signs of overheating. Below is how to do the test.

Pressure testing a cooling system
Pressure testing a cooling system

How to Pressure Test Cooling System

The purpose for doing a cooling system pressure test is to make sure there are no leaks.  This can be when changing coolant, or when you’ve noticed engine problems such as overheating. The cooling system pressure test procedure is explained below.  

Things you’ll need:

  • A cooling system pressure tester kit
  • Water to fill the cooling system if coolant level is low
  • A pan to catch the coolant that may leak

Note: Before everything, ensure the engine is cool. Allow the engine up to 1 or 2 hours if you just were driving your car. Hot coolant can cause burns. Fill the cooling system with water if necessary. Using water will help you avoid wasting your precious coolant.

Next, place pan underneath the radiator. The pan will help catch spilling coolant when you pressurize the cooling system. With everything else ready, here’s how you use a coolant pressure tester:

Step 1: Check the Upper Radiator Hose

  • Touch the top hose of the radiator to make sure it’s cool.
  • Squeeze it to make sure to ensure the cooling system is not pressurized.
  • The hose should be squeezable.

Step 2: Remove the Radiator Cap

  • Find the coolant reservoir (or radiator) of your car and remove the cap.
  • Check the pressure indicated on the cap.
  •  This is the limit that you should not exceed during the test.

Step 3: Connect the Pressure Test Adapter

  • Identify the adapter to use from the radiator pressure tester kit.
  • Deepening on your car type or model, you may not need an adapter.
  • Connect the adapter to the radiator or coolant tan.

Step 4: Connect the Pressure Tester

  • Attach the tester by pushing the connecter into the adapter.
  • Push and twist the connector clockwise until there’s a click.
  • This will ensure a snug fit

Step 5: Operate the Pressure Tester Pump

  • Start pumping the pressure tester.
  • Be sure to check the tester’s pressure gauge all the while.
  • Do not exceed the maximum pressure indicated value.
  • Most cars have a cooling system pressure limit between 10-20 psi.
  • Stop when you reach the pressure limit of your particular car.
  • Watch the pressure gauge reading for some minutes.
  • If the pressure keeps dropping, your cars cooling system is leaking. Inspect it visually.

Step 6: Disconnect the Pressure Tester

  • Once finished testing your car cooling system, disconnect the tester.
  • Start by pressing the pressure release valve.
  • Watch the needle on the pressure gauge drop until it reaches zero.
  • Detach the tester using the reverse of the process you used to install it.
It’s crucial to know how to read cooling system pressure test results
It’s crucial to know how to read cooling system pressure test results

Cooling System Pressure Test Results

You have just finished testing your car’s cooling system for pressure and coolant leak. How do you know if it’s healthy or failing? Here’s is how to read and interpret the results of cooling system pressure testers.

If the pressure holds (the needle stays on the same reading for some time) there are probably no leaks. A drop of pressure is an indication that a section or part of that cooling system is leaking. Confirm by checking using your eyes.

Note: a drop in pressure could result from a bad or incorrectly connected tester, so be sure to check that.

Look for spilling coolant in these areas: around the radiator, radiator hoses, and nearby components such as water pump and fire wall. Other important places to check after a cooling system pressure test include the cylinder head.

Take out the spark plugs and check to see if there are signs of coolant in the spark plug sockets, an indicator that the head gasket is blown. Ensure the system is still pressurized when doing this. Inspect the oil filter too, by opening its cap and checking for the presence of a milky brown fluid.

Lastly, start the car AC fan to detect internal leaks that you cannot see with the eyes. A strong smell of antifreeze when the AC is blowing air into the cabin indicates system that’s leaking internally. Take steps to fix that.  

The best cooling system pressure tester should be usable
The best cooling system pressure tester should be usable

Best Cooling System Pressure Tester

There are many automotive pressure testers out there – some great others not so great. The best cooling system pressure tester should perfectly fit your needs and preferences. To help you make good decisions when buying one, are some of the things to look for:

Ease of Use

Some pressure testers are very easy to use, while others are not. Make sure the temperature gauge is visible and easy to read. The pump should also simple enough to operate. A snap-on cooling system pressure tester connector or adapter is also more desirable.

Pressure Rating

The best cooling system pressure tester will have a high enough pressure rating so you can test different car cooling systems without restrictions. Read the specifications before buying yours. Make sure it can do what you need it to do.

Number of Adapters

A cooling system pressure tester to use on several different cars will have many different adapters. If you do not intend to use your tester on many cars, you do not need those, a simple tester will do. You could also choose a kit that includes adapters that will fit your cars.

Price Factor

The price of pressure testers can vary greatly. If you are on the lower end of this type of product, be careful not to get something that will break or not hold up to the standards that are required. The best cooling system pressure tester for your money is one that has all of the features you need- and is of high quality.

Low-Cost Cooling System Pressure Testers

These pressure tester kits will not have capacity to support many car makes and models. They also do not include additional components and may be made from materials that will not last a long time.

Mid-Price Cooling System Pressure Testers

Mid-price testers will have adapters to serve a wider number of vehicle types or models including custom cooling system caps.  These will have good build quality and materials.

Expensive Cooling System Pressure Testers

A costly tester is compatible with almost any type of car. In other words, it’s a near universal cooling system pressure tester kit that suits both DIY car owners and mechanics or repair shop use. They are also a higher quality in terms of material quality and design or construction.


A cooling system pressure tester is a great tool for any home garage or professional repair shop. When doing routine maintenance, it can help indicate problems before they become major issues, and save you time and money in the long run. Cooling system maintenance is very important for your vehicle, because it can prevent leaks and other problems that may cost you engine damage.



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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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