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When you see symptoms such as engine misfire, loss of power, rough idle, or white smoke coming from the tailpipe of your car, you know it is time for serious engine diagnosis. The intensive diagnosis often narrows down to two things: 1) testing the ignition system, and 2) testing the fuel system.
When troubleshooting the ignition system of a car, one important test that should be at the top of the list is the engine compression test. This test is performed using an engine compression tester kit. It helps to find out if there is enough pressure build-up in the engine cylinders.
What is an engine compression tester?
An engine compression tester kit is a toolset used to test the compression in the cylinders of an internal combustion engine. As you might already know, an internal combustion engine works on the principle of compression and expansion of gases.
Fuel/air mixture is compressed inside the cylinder and an electric spark from spark plugs is introduced. This causes the fuel/air mixture to burn to release very hot combustion gases. The heat energy in the hot exhaust gases pushes the piston up rapidly. As a result, the piston causes the crankshaft to rotate. This back-and-forth movement of the piston due to compression and expansion in the engine cylinder produces the motor power.
If the compression in the cylinders is not good enough, the engine or motor will not produce enough power. This is what most people refer to as loss of power.
There are many causes of low compression in a motor that can be diagnosed quite easily using a good compression tester kit. Basically, a compression tester tool consists of a compression gauge and a spark plug hose assembly. Some kits include additional accessories such as threaded adapters of different sizes, direct shafts, and repair kits.
In this article, we review the 5 best compression tester kits for gasoline engines.
| Bluedriver compression tester kit | Mityvac 5530 Professional Compression Tester Kit | Innova 3612 Compression Tester Kit - 4 Piece | OTC 5606 Compression Tester Kit | Actron CP7828 Compression Tester Kit | |
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| Scale gauge | 0 - 300 PSI | 0 - 300 PSI | 0 - 300 PSI | 0 - 300 PSI | 0 - 300 PSI |
| Adapter sizes | 10mm adapter 12mm adapter 14mm adapter 18mm adater 16mm threaded hose end. | 12mm adapter attaching to the hose.
14 mm short-thread adapter with 6 1/2" (165 mm) and 12" (305 mm) long hoses
14 mm long-thread adapter with 12" long hose 18 mm short-thread adapter with 12" long hose 14 mm short-thread x 18 mm long-thread adapter 10 mm thread small engine adapter 12 mm thread small engine adapter | 12mm adapter 14mm long-reach adapter 14mm and 18mm hose end | 10mm thread adapter 12mm thread adapter 18mm adapter | 14mm long reach adapter 14mm&18mm end test hose end 10mm adapter 12mm adapter |
| Extras | 1 angled direct shaft 1 straight direct shaft | Spare part kits | NA | 12 inches flex with 14mm standard adapter 12 inches long flex with 14mm long reach end | spare kits |
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Best Compression Testers for Gasoline Engine
Bluedriver compression tester kit review
The bluedriver compression tester kit is one of the best compression gauge sets any car owner, mechanic, or DIYer would want to have in their toolkit. The kit is built with exceptional quality and includes all the fittings you need to tackle any gasoline engine compression problem.
Every accessory is packed well inside a blow-molded carry case. To ensure that the 8 pieces remain in place, the inside of the plastic case is lined with foam both on the bottom and top cover. Moreover, the bottom foam lining has slots to fit each accessory so that everything remains together even if you flip the case.
Bluedriver compression kit accessories
As mentioned above, you get a collection of fittings with the bluedriver compression gauge set. In addition to the 2.5 inch triple scale gauge, there is a 16-inch spark plug hose with 14mm&18mm end. The kit also includes 4 additional adapters. The sizes of these extra adapters are 18mm, 14mm, 12mm, and 10mm. Furthermore, you also get two universal direct shafts (straight and angled). These direct shafts let you perform a compression test on small and large engines that do not accept the screw-in adapters. These additional accessories make the bluedriver compression tester kit suitable for any type of petrol engine.
Application
The bluedriver engine compression tester has all you need to test the compression of the gasoline engine of your car. The kit also includes the accessories you will need to use it as a small engine compression tester right off the shelf. You do not need to buy extra attachments to test the compression of your motorcycle or chain saw when you have the bluedriver kit. This kit has all you need to tackle the compression issues of any petrol engine. The bluedriver test kit is inexpensive and easy to use. As such, it is good to add it to your toolbox for diagnosing compression issues to avoid unnecessary costs.
Mityvac compression tester review
The Mityvac 5530 professional compression tester is another very effective tool kit for performing engine compression test. The kit consists of multiple accessories packaged nicely in a molded plastic case. The rugged carry case makes it easy to store the kit securely in the tool box. It has a handle that makes transportation of the kit very easy.
Mityvac Compression tester accessories
Besides the 2 3/4 inch gauge dial, Mityvac kit includes multiple adapters and hoses of different sizes and designs. Among them are two small engine adapters of sizes 10mm and 12mm and another adapter with 14mm x 18mm end. The kit also comes with four extension hoses. Three of the hoses are 12 inches long with 14mm long thread adapter, 14mm short thread adapter, and 18mm long thread adapter respectively. The fourth hose is 6 inches long with a 14mm short thread end. There are also additional accessories such as field service kit and a quick-release air hold adapter. The field service kit comprises useful repair tools including a valve core removal tool.
Applications
The mityvac compression tester kit has all the adapters you need to fit large and small gasoline engines. This makes the tool very useful for performing dry and wet compression test on cars, motorcycles, lawnmowers, chainsaws, and other petrol engines. Furthermore, you can use the pressure hold adapter included in the kit to perform valve seal replacement without removing the cylinder head.
Innova Equus 3612 compression tester review
The Innova compression tester is an inexpensive, easy-to-use engine compression diagnostic tool. It consists of 4 pieces including a compression gage, a spark plug hose, and two additional adapters. All four parts are packaged nicely in a clear clamshell. Although the packaging is not as good as having a molded case, the clamshell can protect your tool for long if you use it carefully. Otherwise, you may consider getting a generic sturdy gauge case, especially if you are a regular user. Moreover, if you plan to put this kit inside your toolbox, I would advise that you get a solid carrying case.
Innova 3612 accessories
As mentioned above, the Innova 3612 kit has only four pieces. A 2.5-inch diameter compression gauge, compression tester hose, and 12mm and 14mm tester adapters.
Compression gage
The gauge is dual-calibrated with the psi and kPa measuring scales. Its scales are painted black against a white background, creating a very good contrast that allows you to read compression results from a distance.
Furthermore, the red and green color-coding on the gauge scale gives you a quick visual impression of the health of the engine cylinder. Also, the outer metallic casing is beveled on the edges to protect the glass face of the gauge. This keeps the glass from breaking when it falls on a flat surface.
Compression tester hose
The second part is a spark plug hose assembly. This hose measures 17 inches in length. One end has a brass fitting that fits onto the quick connect end of the gauge. The other end is a combined 14mm & 18mm brass adapter end that is also fitted with the Schrader valve core. This means that you can fit the hose directly onto a 14mm short thread or 18mm long thread spark plug hole.
Compression tester adapters
The other two pieces are 14mm and12mm compression tester adapter ends. These adapters are also made of brass and fit very tightly to the spark plug hose assembly. The 14mm long reach adapter is suitable for most engines while the 12mm short reach adapter works well for small gasoline engines.
Application
The different sizes of adapters coupled with an accurate and sturdy compression meter make the Innova compression tester kit a versatile diagnostic tool for home and professional use. You can use it to test the compression of both small and large gasoline engines to detect issues such as damaged pistons, worn piston rings, burnt valves, and blown head gaskets.
OTC compression tester review
OTC is a household name among auto mechanics because of the countless number of automotive diagnostic tool kits. Some of the common OTC tools include the OTC fuel pressure tester, battery load tester, and the OTC leak down tester among others. All these tools are great and the OTC compression tester kit is equally as good. The OTC 5606 cylinder compression tool set has 8 pieces including compression gauge meter, three adapter ends, three hoses, and spare kits. All these pieces come packaged nicely in a solid blow-molded plastic case.
OTC 5606 compression kit accessories
OTC compression gauge
The OTC kit has one of the best compression gauges. The gauge measures 2.5 inches in diameter just like the Innova. It also has a dual scale gauge of between 0 – 300 psi or 0 – 2100kPa if you like. One outstanding feature of the OTC compression gage besides its accuracy and versatility is the protective rubber boot around the dial. This rubber boot protects the head from impact thereby increasing its durability.
Compression tester hose
The OTC kit has a reasonably long compression tester hose. The hose measures 25 inches long, 8 inches longer than the Innova hose assembly. This makes OTC suitable for spark plug holes located far inside. The hose is permanently fitted to the gauge on one end while the other end is a quick-connect coupler.
Adapters
Other accessories as listed in the comparison table above include 18mm, 12mm, and 10mm compression tester adapter. These adapters are nickel-plated to prevent rusting and fit very well on both flat and tapered seat plugs. They all have short threads. Additionally, the kit has two more hoses fitted with 14mm short and long reach adapters. All these adapters make the OTC compression tester kit ideal for all types of gasoline engines.
Repair parts
The OTC compression kit includes extra O-rings and Schrader valve cores. These repair kits fit on the threaded end of the spark plug hoses supplied with the tool. In particular, the O-ring ensures that the spark plug hose seals properly with the plug hole. On the other hand, the schrader valve allows compressed air to flow only into the gauge, allowing the freezing of the compression test results. These two parts are very important and it is such a good thing to have spares.
OTC compression tester application
The multiple adapters and the good construction make the OTC compression tester kit a very versatile diagnostic tool. You can use it to test the compression of different types of gasoline engines including your gasoline car engine, lawnmower, power saw, motorcycle, and water pump among others.
Actron compression tester review
Just like the OTC diagnostic tools, Actron is also a major player in the manufacturing of automotive diagnostic tools. The company is famous for some of the best automotive diagnostic tools such as the fuel pressure kit, fuel pump diagnostic kit, OBD scan tools, infrared thermal scanners, and engine compression testers.
The Actron CP7828 compression tester kit consists of 7 pieces including a compression gauge, three adapters, a test hose, a long reach adapter, and a couple of spare schrader valves and O-rings. Unfortunately, the kit does not include a carry pouch or blow mold case to store the parts securely. They come in a clear clamshell.
Actron CP7828 Accessories
Actron compression gauge assembly
The Actron compression meter has a 2 1/2 inch dial, just as big as the Innova and OTC alternatives. It is well built for both home and professional use. Like the other compression gauges reviewed so far, the Actron gauge also features a Bourdon tube mechanism that provides accurate compression test measurements. The gauge assembly has a white face that creates a very good contrast for reading compression test results from the standard and metric scales. It also features a push-button release valve on the neck for resetting the gauge. In addition, the gauge assembly features a quick connect mechanism that allows for easy connection and disconnection for the test hose. To increase its durability, the bourdon tube housing has a heavy-duty protective rubber boot. The boot protects the tool from impact.
Actron Compression kit adapters
The Actron CP7828A compression tester kit has 4 adapters that are compatible with most standard spark plugs. Two of the adapters are M10 and M12 and are suitable for small gasoline engines such as the 2 cycle engine in a motorcycle, trimmer, and gasoline chain saws. The other two adapters are a 14mm deep reach adapter and an 18mm metal extension adapter for recessed spark plug wells. All the adapters have a nickel-plated finish to prevent rusting. Moreover, both the metal extension adapter and the spark plug hose assembly have a schrader valve on the adapter end which increases the accuracy of the kit.
Handy repair kit
Because schrader valves and O-rings in compression tester kits wear out fast, the Actron kit includes spare O-rings and schrader valves. These keep the tester kit longer before you start going to the hardware store for spares.
Actron compession tester kit application
The Actron compression kit is very durable and versatile. This makes it suitable for home use and professional use. A motorcycle repair guy in my neighborhood uses this kit as a motorcycle compression tester and it works like charm. In general, you can use the Actron engine compression tester for testing cylinder compression of foreign and domestic vehicles, small engines, motorcycles, snowmobiles, and ATVs among others.
