A compression test can be a useful diagnostic tool to help identify many potential problems with your engine. A compression tester, also known as a compression test gauge, is the tool required to perform a compression check and can be extremely useful in trouble shooting problems such as faulty head gaskets, leaking valve seals or valve guides, worn piston rings, etc.
A compression tester kit typically consists of a gauge, high pressure hoses, and a variety of fittings to mate the gauge to the spark plug holes that lead to each cylinder. To use one, you remove all spark plugs, disconnect your fuel pump (or remove your fuel pump fuse) to prevent fuel from firing through your injectors, and connect the gauge to one of the cylinders. You then crank the engine four or five times until maximum compression is achieved and take your reading. Rinse and repeat for each cylinder you intend to test.
When choosing a compression tester, you will typically want to choose one with a variety of fittings which allows use on many makes and models of cars, and you’ll want a gauge that goes to at least 300psi which will cover the highest compression gasoline engines. Diesel engines can often require higher pressure readings.
The Best Compression Testers
When it comes to choosing the best compression tester, there are tons and tons of options out there. Below we have chosen our favorite overall compression tester and our favorite budget compression tester to ease the search process.
Best All Around: OTC 5605 Deluxe Compression Tester Kit
OTC is a longstanding toolmaker in the automotive business. While they are well known for their great jack stands, they also make other tools including compression test kits. Their 5605 Deluxe is our favorite kit around. First, it has a 300 psi blue faced gauge which is perfect for any automotive gasoline motor. It comes with a full assortment of adapters to fit both standard spark plug holes as well as less common sizes such as those for some motorcycles.
The hose for the gauge is a solid 25″ long, so you won’t be hunching over your engine bay to reach it when you have it hooked up. The gauge is well protected and has a grippy surface so you won’t accidentally drop it during use.
Additionally, it comes with a nice carrying case to store all of the small parts that come with the kit. Overall, the quality and accuracy are great. This is a tool that will last quite a while, and you won’t have to buy more adapters or buy a new gauge as this one will have pretty much everything you need for almost any vehicle. The OTC 5605 Deluxe Compression Tester Kit gets out highest recommendation and is worth the money if you plan to use it multiple times.
Best for Budget: Innova 3612 Compression Tester 4 Piece Kit
If you are looking for a one time use tool to judge the health of an engine, the Innova 3612 the one to get. Considering it is one third the cost of the above OTC, it is an extremely high value. Like the OTC, it has a rather svelte 300 psi gauge with an attractive white face dial. The gauge features a quick disconnect which allows you to remove the gauge when installing the hose to make installation easier.
The gauge comes with a pair of adapters and a single 15 inch hose. This is enough to get you by for most cars that have the most common spark plug sizes. That said, if you have a specialty car or one with unconventional spark plugs, you will likely have to go with something like the OTC instead.
Overall, quality is decent but doesn’t match that of the OTC. As mentioned, this is a great option if you are checking out a car before buying or just planning a one time diagnostic on your car that requires a compression test. For our money, we’d still take the OTC but if you are looking for something quick and cheap, the Innova 3612 will definitely do the job and do it well.
So there it is, a quick breakdown of our favorite compression testers. While we have reviewed what we think are the best compression testers that we have come across, if you find that neither are right for you then feel free to take a look at some of the other product offerings on the market by clicking here. Happy wrenching!