The Best Cylinder Leak Down Test Kit

By on 13 January 2021 / Leave a comment Updated on: 16th February 2021

Knowledge, they say, is power. Without information no-one would ever know where they went wrong. A test paper without marking gives no feedback to a student, like an engine malfunction without a cause gives no clear resolution.

Diagnosing serious engine woes may sound like a job best left to a professional mechanic but, even an extensive test such as a leak down test, that can help identify clearly the exact issue a motor is facing, can be performed at home on the driveway with a few basic tools and just a few hours of free time.

Leak down testing kits are now widely available, will likely set you back less than a diagnosis at a main dealer and will give piece of mind, knowing the issues your vehicle may be facing. Blindly taking a mechanics word for it can sometimes be scary, particularly when the monetary outlay is seriously large. Performing a leak down test with one of the kits outlined below takes away the worry and shows owners the path to a healthy engine and reliable vehicle.

The Benefits of Leak Down Test Kits

A tester kit (such as those below) can help diagnose current issues, they are also extremely useful to check for leaks in the case of a new/ potential vehicle purchase. Understanding how well an engine is holding compression is likely a good indicator of how well the car will perform, the level of maintenance the previous owner(s) have performed and the mechanical reliability of the vehicle’s engine going forwards.

Performing the test does require some basic tools such as a socket set, screwdrivers and a breaker bar. These allow for access and removal of the spark plugs, finding top dead centre and holding the piston in place during the test. Videos for all these tasks are easy to find on YouTube or through workshop manuals, with most DIY enthusiasts easily up the job. The test kits also require compressed air, meaning an air compressor is also essential.

The basic design of the kits allows them work with both petrol and diesel engines. Most kits however, will only come with adaptors for spark plug holes, not present on diesel vehicles. This means that diesel owners need to choose the kit carefully and ensure they purchase an adaptor where required, with the knowledge that diesel vehicles operate with much higher air pressures than petrol engines and therefore require robust and high-quality equipment.

The Best Cylinder Leak Down Testers on the Market

Draper Cylinder Leakage Kit

draper cylinder leakdown tester

Check the latest price on Amazon

Over 100 years of experience and a huge portfolio of tools are the things that make UK tool manufacturer Draper a brand you can trust. The company not only manufactures their own tools but also oversees operations at other tool brands such as Britool and King Dick. Such a long period in the industry has seen Draper on shelves in most garages, from basic DIY toolsets to professional workshops. Draper is constantly striving for better products and excellent customer service.

The leakage kit that Draper provides is similar in concept to all competitors (the basic operation of all leak down tests is fundamentally the same). Testing using this equipment will give accurate results, helping determine common engine faults such as worn piston rings, cracked cylinder heads and blown head gaskets. The coloured coded gauges give a clear representation of air pressure and leakage percentage.

Compatible with both indirect and direct injection petrol engines, with adaptors for 10, 12, 14 and 18mm spark plug threads, there is likely no petrol vehicle on the UK market that this kit will not work with. The kit also comes with a handy plastic storage case, useful for transporting the kit and keeping it tidy.


  • Least expensive kit listed here
  • Well trusted UK tool manufacturer
  • Compatible with almost all petrol vehicles
  • Easy to understand with clear representation of leak percentage


  • No adaptor for diesel engines

OTC Cylinder Leakage Tester Kit

otc cylinder leakage tester

Check the latest price on Amazon

US-based OTC takes a different approach to the UK competition. They are a brand under the Bosch electronics group, known internationally for supplying automotive electrical hardware, software and specialist tools. OTC therefore, are a brand that focusses on highly specialised tools, aimed at providing professional quality to home mechanics and DIY enthusiasts. Since 1925, the company has been growing and expanding its operations and product portfolio, recently breaching into the UK tools market.

OTC promises that their kit gives highly accurate results, is simple to setup and can be used by anyone with a little bit of technical knowledge and mechanical experience. Clear gauges give an accurate pressure reading and leakage percentage to help owners and mechanics alike, hone in on the possible causes of a poor running engine.

Compared with the Draper offering, the kit is a little short on adaptors, compatible with 10, 12 and 18mm spark plug holes only. This will however, still provide great usability for most petrol-engined cars on UK roads, while the handy case makes the kit very portable.


  • Manufacturer that focusses on specialist tools
  • Highly accurate pressure and leakage readings
  • Enables owners to establish root cause of engine issues
  • Suitable for most petrol engined vehicles


  • Brand not so well known in the UK automotive tool sector

Laser Cylinder Leakage Tester

laser cylinder leak down test kit

Check the latest price on Amazon

Lastly, we have the leakage tester from Laser Tools. Laser Tools are a UK-based manufacturer of tools and parts, ranging from plastic fixing screws to air compressors and even PPE. They don’t just hold a huge range of products, they also back their claims about quality and durability, supplying professionals in the automotive industry as well as home mechanics and DIY enthusiasts. The company has been active since 1976, constantly bringing new products to market, whilst also improving on current offerings.

Like the competition, Laser’s leakage tester kit promises highly accurate pressure readings, giving the user the best chance of narrowing down the possible issues within the engine. Coloured coded gauges (as seen in the Draper kit) makes it very easy to identify the level of leakage being experienced by the engine. Solid build quality should see the tester last for many years and hundreds of uses.

Unlike the aforementioned kits, the Laser Tools leakage tester comes with extended adaptors for deeply seated spark plugs, in both 12 and 14mm sizes (standard length 10, 12 and 14mm adaptors also provided). The real trump card of this kit however, is the inclusion of a diesel adaptor hose, rated at a higher 300psi to withstand the greater pressures of a diesel engine. This extra functionality and adaptability do come at an increased purchase price though.


  • Highly regarded UK tool brand
  • Colour coded gauges for ease of use
  • Usability with diesel engines (high pressures) signals a strong and high-quality product
  • Includes adaptors for diesel vehicles and deep-seated spark plugs


  • More expensive than aforementioned competitors

In Conclusion

Tasks such as a leak down test often seem as though they require expert knowledge and tools to perform, that is the basis on which most garages make profits. Those with a little know-how, some basic tools and an interest is understanding their vehicles engine (and any current issues) can save huge amounts of money and time performing these tests at home. The kit will likely last a lifetime and can be used on an unlimited number of future vehicles (with petrol/ diesel engines).

Performing a leak down test before handing over wads of cash for repairs could save vehicle owners thousands, allow them to understand their vehicle better and maybe pick up some new DIY skills along the way. Get your vehicle running right or just give yourself the piece of mind that your new purchase will continue to drive reliably. Give one of these testers a chance today, I doubt you’ll regret it.

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Jack Gill

Car journalist and fully qualified mechanical engineer, Czok’s newest contributor and long-time automotive writer. Lifetime passion for all things automotive, from new supercars to rusty old hatchbacks. If I’m not behind the wheel, I’m likely under the bonnet or browsing the classifieds. Having spent over 5 years in the automotive industry and under the bonnet of my own car at home, I want to share the knowledge and learning that I have gained, with others without the time to study or the expertise, who just want their car to get them from A to B every day. We aren’t all interested in trawling through endless internet pages and forums. I aim to gather all the information up and roll it into a quick summarised format, to give only the information you really need.

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