Compression testing is an extremely valuable diagnostic exercise for ensuring the continuing health of your L-series engine, or really any engine. Of all the critical factors necessary for reliable engine performance, a good compression level is certainly one of the most critical. Compression testing allows you to accurately measure the level of compression your engine is receiving in each cylinder while the engine cranks. This is a useful diagnostic tool because it quickly signals you to potential issues in your engine that you may not have known about otherwise.
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Every good mechanic needs a decent compression tester, or test kit. This is not the kind of tool you should be renting from the auto-parts store. Not only are they absolute lifesavers, but they can also be quite inexpensive, and we’ll be sure to point out some of the more affordable options in this guide. This guide contains the 5 best compression testers you can buy for your L24, L26, L28, or any engine!
#1 OTC 5606 Compression Tester Kit
The OTC 5606 is a versatile compression tester kit that should get the job done in almost any scenario you’ll find yourself in while testing your engine’s performance. The OTC 5606 features some of the most commonly needed adapters so you wont be left doing an extra run to the auto parts store. This compression tester kit contains a nearly two foot long flex hose, which comes in handy in a cluttered engine bay. The gauge is analog and reads 0-300 psi and 0.211 kPa.
The OTC 5606 features corrosion resistant nickel plated finish, and its adapters work on both flat and tapered seat plugs. The entire assembly is rugged and should withstand average garage “abuse”. The OTC 5606 comes with a protective carrying case so you can transport it easily or just have a dedicated space for it in the garage. This is our pick for the best all-around compression tester kit that will be more than adequate for the average mechanic or hobbyist.
#2 Actron CP7827 Compression Tester Kit
The Actron CP7827 compression tester kit is a cheap option for a mechanic who just wants a simple solution that he can expect to work. This is a fairly limited product in a number of ways. To start, the CP7827 comes with only 14mm and 18mm adapters. These are fairly standard sizes so this solution will fit the vast majority of engines you’ll want to use it on (including L-series engines) but you may find yourself buying new adapters if the engine you’re working does not have 14mm or 18mm spark plug holes. Another limitation is that the actual cable is quite short and it might limit your ability to use this tool effectively in some engine bays. According to Amazon reviews, some purchasers of this item are frustrated by the lack of a hex nut on the end of the gauge, so you cannot tighten the connection by wrench. This could be problematic in compression testing where a loose connection could lead to highly innacurate readings. One helpful feature is that the gauge quick disconnects which is helpful when changing cylinders during a compression test. Overall, this is of solid build quality and will last a long time. It is a more inexpensive option than anything else you’ll see on here, but for the price point it appears to be a great option!
#3 Mityvac MV5532 Digital Compression Test Kit
The Mityvac MV5532 is the “buy it for life” option here. The MV5532 contains a wide variety of adapters so that you’ll never be left stranded without the proper one. The most significant distinction offered by this compression test kit is that it offers a digital gauge. This has two advantages, the first being that you can cycle through a number of different units. So, whatever your service manual chooses to specify for compression, you can just set the unit on your Mityvac MV5532 ahead of time so you don’t have to do any conversions. Secondly, this compression test kit is able to save your readings as you go, so you don’t have to pause to record your readings on a notepad after each cylinder! This is extremely helpful as compression testing is often a tedious task and it is important to go through all of the cylinders quickly. The screen uses a backlit display so you can still read it in darker corners of the engine bay.
While this option is certainly more expensive than the others, it is worth it as again, this is a lifetime purchase. If you’re going to spend money on any tool, a diagnostic tool is a great way to spend the money as an improper engine diagnosis could lead to endless amounts of money down the drain later on. Compression testing is arguably the most critical test you can run, so the Mityvac MV5532 seems well worth it for all its bells and whistles.
#4 INNOVA 3615 OHC Compression Tester Plus
The INNOVA 3615 compression tester is an extremely versatile compression tester that makes use of very high quality materials. This compression tester is designed to access recessed spark plugs holes on vehicles with difficult to access points. The INNOVA 3615 compression tester comes with 10mm, 12mm, 14mm, and 18mm adapters and a 14mm long reach adapter for engines that make it extra difficult to access the spark plug holes. This compression tester kit also comes with an 8-inch long-reaach adapter that can be used with any compression tester, not just the INNOVA 3615. This is particularly useful on a 300ZX with the layout of its engine bay.
This option does not come with any kind of carrying case, so you may want to choose one of the other options if you plan to be more mobile with this device. For the regular at-home garage mechanic, this shouldn’t be a problem. Overall, the INNOVA 3615 OHC Compression Tester Plus is a great all-around compression tester that should maintain its accuracy for a long time.