LAST UPDATED: October 10, 2019
Best Compression Testers: Diagnose Your Engine with Ease
Test your engine’s capabilities quickly and efficiently with these top-rated compression testers
The Review Team
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PUBLISHED ON October 10, 2019
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.
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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.
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 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 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.
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.
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.
- 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 2020
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.
Compression tests are usually conducted on parts of the engine you can't always see. The great thing about this compression tester is that it can perform compression testing on parts of the engine that may be difficult to access. It comes with 14mm and 18mm spark plug adapters and can test engines in a wide range of vehicles.
This set has all the tools needed to check engine valves and piston rings. Its three-inch gauge has a dual color scale with a range of 0-300 psi. When you need to perform a quick engine check, simply use the two rubber cone ends, as they do not need to be threaded into the head.
However, despite its great features, it has several shortcomings. For starters, it gives variable results that are lower than those given by other compression testers in the same category. The rubber cone ends are also a bit flimsy and tear easily.
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 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.
- 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.
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.
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.