Reviews

Best Compression Testers: Diagnose Your Engine with Ease

Test your engine’s capabilities quickly and efficiently with these top-rated compression testers

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BY Linsay Thomas , Scott Roepel / LAST UPDATED ON May 3, 2021

Has your check engine light ever flickered on and you’re not sure why? You could take it to a mechanic, but he or she may overcharge you just to diagnose the problem. Or you could use a compression tester to discover what’s wrong. The tool diagnoses problems in the engine and alerts you of any dangers or mechanical failures. In this buying guide, we highlight the best compression testers on the market.

Best Overall
Innova Compression Tester
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Summary
Summary

This versatile tester works on electronic and computerized domestic or import vehicles. It features a 15-inch-long rubber hose, three valve adapters, and a side release valve.

Pros
Pros
  • Features a large dial face with an easy-to-read meter and a durable rubber hose
  • Has dual-calibrated and color-coded scales
  • Device also functions on motorcycles, ATVs, snowmobiles, and marine vehicles
Cons
Cons
  • You may need adapters to connect it to motorcycles and ATVs to connect it to the spark plugs
  • Does not come with a carrying case
Best Overall
Innova Compression Tester
Best Value
Orion Motor Tech Engine Compression Tester
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Summary
Summary

This eight-piece set can be used with cars, trucks, motorcycles, ATVs, and more. It has straight, curved, and male adapters.

Pros
Pros
  • The display is easy to read and features two different units
  • Cover is anti-scratch and shock absorbent
  • Great overall kit for the price
Cons
Cons
  • Not as accurate as some rival brands, so not the best option if precision is critical
Best Value
Orion Motor Tech Engine Compression Tester
Honorable Mention
Mityvac Professional Compression Tester Kit
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Summary
Summary

This kit has everything required to perform wet and dry engine cylinder compression tests, which are used to detect cylinder head or ring problems, blown head gaskets, and sticking valves.

Pros
Pros
  • Has manual pressure release to maintain peak readings
  • Adapters allow it to fit engines for smaller machines like chainsaws, lawn mowers, and trimmers
  • Adapters are threaded for leak-proof seals
Cons
Cons
  • When dealing with a  recessed spark plug hole, you have to twist the adapter into the plug hole by applying torque on the hose
  • Online purchases are not warrantied
Honorable Mention
Mityvac Professional Compression Tester Kit

Why Trust Us


Our reviews are driven by a combination of hands-on testing, expert input, “wisdom of the crowd” assessments from actual buyers, and our own expertise. We always aim to offer genuine, accurate guides to help you find the best picks.

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Benefits of a Compression Tester

  • Reveals engine condition. A compression test shows the condition of an engine's piston rings, valves, and valve seals. It also shows if these parts are wearing evenly.
  • Preventive maintenance. Every time a tune-up is done, it is important to do a compression test to ensure the engine lasts as long as possible. Preventing a problem is a lot cheaper than fixing it once it happens.
  • Early problem detection. When you perform a compression test, you can identify internal engine malfunctions such as excessive carbon buildup, bad valves, and faulty piston rings. The test detects problems before they cause irreparable damage.

Types of Compression Testers

Screw-In Compression Testers 

A screw-in compression tester has a hose connected to it and a fitting on the end. The fitting screws into the spark plug opening and fastens it with an O-ring. This type of compression tester works on almost every type of engine and does not require two people to do the test. It is the best tester if you are planning to do a lot of engine work.

Rubber Plug Compression Testers

A rubber plug compression tester works very fast and features a rubber plug (a rubber nipple). To do the test, simply push the rubber plug into the spark plug hole and crank the engine with the starter. A rubber plug compression tester has one big disadvantage: to do the test, you need two people. One person holds the tester while the other cranks the engine. The other disadvantage with this tester is that it doesn't work on most modern engines that have spark plugs recessed deeply into the cylinder head or valve cover.

Top Brands

Innova

Innova electronics corporation was established in 1990. The company manufactures motor vehicle parts and accessories. All its products are designed and developed at its headquarters in Irvine, Calif. Its innovative diagnostic products diagnose issues before they develop into bigger problems. If you're looking for a compression tester that won't disappoint you, get the Innova Compression Tester Plus Kit.

OTC

OTC is a major manufacturer of vehicle electronic diagnostic equipment and automotive accessories. In 2012, it was acquired by Bosch and was incorporated into the Automotive Service Solutions Business unit of the corporation. The company is located in Owatonna, Minn. It is known for its powerful compression testers like the OTC Compression Tester for Gasoline Engines.

Lisle Corporation

Lisle Corporation was founded back in 1903 and is based in Clarinda, Iowa. The privately-owned company is run by family members. It has come a long way since it produced its first product, a horse-powered water well drilling machine. These days, it manufactures automotive tools, lubrication, tire products, and mechanic's creepers. Get the Lisle Compression Tester to diagnose your engine every now and then.

Compression Tester Pricing

  • $20-$50: These compression testers check compression in gasoline engines. They come with adapters that fit most applications.
  • $50-$100: Compression testers in this category are made by renowned brands like Mityvac, PMD Products, 8MILELAKE, and BETOOLL. Most are suitable for automotive engines, industrial engines, and marine engines.
  • $100-$200: In this class, you’ll find digital compression test kits and kits that are designed to test specific engines. They have 300-psi gauges.

Key Features

Gauge

This is the most crucial part of a compression tester because it shows how much compression is in the engine. The tester should deliver accurate readings and should also be large enough to allow you to read easily. There are two types of gauges: digital gauges and dial gauges. Digital gauges are the most accurate. They can also store readings as you carry out compression tests for different cylinders. However, they usually cost more than $100. If you can afford one, get it.

Extra Tools

Most compression testers only comprise a hose and a gauge. However, some kits come with adapters and even carrying cases where you can keep everything. The more tools included in a kit, the better, because they make the compression tester more versatile. For example, a compression tester with different adapters and hoses can test a small engine in a lawn mower, a car engine, and even an industrial engine. 

Ease of Use

The great thing about compression testing is that you can do it on your own, and you don't have to go to the neighborhood mechanic each time you want to check your engine. However, ensure the test kit you get is easy to use so you can carry out the test easily. Make sure the gauge is easy to read and be sure to go through the instructions in the manual before you get started.

Other Considerations

  • Carrying Case. Compression testers that come in a case make your job easy, as you can quickly organize things. The case also ensures that all the tools are protected against damage, increasing their lifespan. You'll also find it easy to transport the tools to the site. If you don't get a compression tester kit with a case, you may have to buy a case later on.
  • Construction. The best compression tester kits are usually made using high-quality materials to be durable. When buying a compression tester, look for one with a rubber boot, as it will easily withstand drops and shocks. If it is a digital unit, make sure it has a grease oil–resistant face.

Best Compression Tester Reviews & Recommendations 2021

Best Overall
Innova Compression Tester

This is the top compression tester in our buying guide because of one standout feature: it is compatible with traditional, electronic, and computerized vehicles. It identifies blown head gaskets, burnt valves, worn rings, and damaged pistons. You can easily check the readings on the 2.5-inch dial face with color-coded and dual-calibrated scales that give a range of 0-2,100 kPa and 0-300 psi.


The scales on this compression tester make it easy for you to get accurate readings when testing your car’s engine. The quick disconnect fitting makes for easy installation while the heavy-duty bourdon tube meter gives highly accurate measurements and allows for repeated tests without disconnecting the hose.


Even though this compression tester comes with a high-pressure rubber hose and different adapters, the manufacturer doesn't include a carrying case, so it is not easy to transport. You also need to get other adapters if you want to perform compression testing on motorcycle and ATV engines.

Best Value
Orion Motor Tech Engine Compression Tester

The Orion Motor Tech Engine Compression Tester is a complete eight-piece set that allows you to test gas engines on cars, trucks, motorcycles, ATVs, snowmobiles, boats, and more. The kit comes with straight, curved, and male adapters, so it's compatible with numerous vehicles. It includes a spring buckle gauge, a straight rubber cone end adapter, a curved rubber cone end adapter, four brass adapters, and a 14-inch extension hose.


The instrument panel is easy to read and includes dual units: 0-300 PSI and 0-20 kg/cm2. The gauge cover has an anti-scratch coating and rubber protection to absorb shocks. All the items are contained in an ABS case. The fittings can accommodate most or all of your needs for most engines, and it's a great kit overall for the price. Plus, the manufacturer will issue a replacement or refund if you're not satisfied with its performance.


Unfortunately, there have been some complaints that the tester is not as accurate as some rival brands. If you want more precise readings, you may want to choose a more premium model.

Premium Pick
Mityvac Professional Compression Tester Kit

Even though this professional compression tester kit sits on the higher end of the price range, it is great because it can test automotive, marine, industrial, and small engines (like those found in lawn mowers). The air hold quick connector allows you to connect the air supply to the valve stem seal without removing the cylinder head.


One thing you'll love about the Mityvac Professional Compression Tester Kit is it comes in a molded carrying case for easy storage. You will enjoy having it in your garage because it will help you quickly figure out different motor issues. It gives very accurate readings and is easy to use. You can easily see the compression readings thanks to the gauge with a color scale. 


However, this tester has one major downside. If a spark plug hole is recessed, you have to apply torque on the hose in order to fix the adapter in the plug hole. Another downside is that online purchases aren't backed by a warranty.

Best for Home Mechanics
OTC 5605 Deluxe Compression Tester Kit

The OTC 5605 Deluxe Compression Tester Kit comes with standard and specialty adapters and contains everything you need to test gasoline engines. It includes an eight-inch deep well 14mm connector and a five-inch flex Ford Triton 16mm adapter. The adapters are compatible with flat and tapered seat plugs.


The metal components are made with a corrosion-resistant, nickel-plated finish. The kit includes an extra-long, 25-inch flex hose gauge assembly with a quick coupler, so you can more easily see cluttered engine components. The dual scale 2 1/2-inch gauge shows readings from 0-300 PSI and 0-2100 kPa. It has a chrome bezel and a durable protective outer boot. All items are contained in a tough, blow-molded hard case. Users report that this kit is worth the extra money. It's accurate, well made, and the deep well attachment comes in handy.


However, it may be tough to thread the fitting with the hose attached when you use it in tight spaces. Also, it's possible to leave the adapters inside the spark plug holes, and it can be difficult to get them out.

Honorable Mention
BETOOLL Compression Tester Kit

The BETOOLL Compression Tester Kit is compatible with gas engines and is designed to help you find hard-to-spot engine problems. It includes seal rubber rings to ensure that the reading is accurate. The solid brass adapters are corrosion-resistant, durable, and leak-free and come in four sizes: 18mm, 14mm, 12mm, and 10mm.


The kit includes a 16-inch-long hose with a push-button release valve and a 45-degree universal direct shaft and a straight universal direct shaft. The gauge provides three different types of readings: 0-300 PSI, 0-20 bar, and 0-20 kg/cm2. Everything is stored in a durable, molded plastic case. Overall, this kit is of good quality and gets the job done.


One downside is that it may not fit in Y block cylinder heads. It may also not be as accurate as more premium brand names.

Tips

  • It’s best to have a dedicated space to store the compression tester and its components. If it doesn’t come with a case, you can either buy one for it or store it in a toolbox.
  • It is always wise to have multiple adapters for your compression tester. Not every vehicle is created the same, so owning different adapters at various lengths will ensure you can check a number of vehicles.
  • A small amount of condensation or dirt can interfere with the device, causing it to produce incorrect readings. Always place every part and the tester in its protective case, and store it somewhere dry and cool.

FAQs

Q: Will a compression tester work on gasoline and diesel engines?

A: A compression tester will work on both types of engines. They are designed to test spark plugs and injector sockets in your engine to measure the amount of pressure in the engine.

Q: How does compression tester work?

A: The compression tester comes with a hose that connects to the spark plug hole of each cylinder. The gauge then hooks up to the opposite end of the hose. After turning on the engine, the needle will climb to a certain number that you need to keep track of. After doing this for each cylinder, all the readings should be similar or within 10 to 15 percent of each other.

Q: What PSI should my engine be registering?

A: Each cylinder should register at 100 or more PSI to be considered healthy. A good target goal should be around 180 to 220 PSI.

Final Thoughts

For a high-quality compression tester with a selection of adapters and long hose, consider the Innova Compression Tester

Or there’s the PMD Products Compression Tester Test Set, which comes in a handy carrying case with plenty of adapters at a cheaper price.