A compression tester, also known as a compression gauge, is an important tool used to diagnose internal problems that may arise within an engine. The best diesel compression tester will support a high-pressure range, come with several attachments, and will screw into the spark plug opening (Source).
A compression tester provides a way to check an engine for internal problems without having to disassemble it entirely. A typical compression tester can test for pressures of up to around 300 PSI (Pounds per Square Inch), but for diesel engines, a gauge that works up to 1000 PSI is required.
A compression tester kit consists of gauge, high-pressure hoses, and a fitting to attach the gauge to a spark plug hole. The gauge can be either digital or analog, and the higher end test kits include multiple fittings for compatibility with different engine types (Source).
Some compression testers do not screw into the spark plug hole, but instead, one person has to hold a fitting down onto the spark plug hole while another person attempts to crank the engine. This type is good to avoid, considering they are not compatible with most modern engines and require two people to operate.
Before purchasing a compression tester, consider the attachment method, price, compatibility, and reliability. You should also consider the maximum pressure reading and other top aspects.
In this review, we will check out the top-rated diesel compression testers. All of the models in this guide will be ideal, whether you’re a professional mechanic or someone that just works on their personal vehicles.
What is a Diesel Compression Tester?
A diesel compression tester is a simple tool that anyone with a diesel engine should definitely consider picking up. They allow you to run diagnostic tests that will help you to identify any issues within the engine itself and can even help to prevent these from occuring in the future.
At first glance, they may look very similar to the pressure testers that are used for gasoline powered engines, but diesel compression testers are designed specifically with diesel engines in mind. This is necessary because these engines operate differently, mostly due to the increased pressure that is present in diesel engines.
While many of these testers will be sold as an entire kit, we will discuss the various parts that you might find within to help you further understand the finer details. Most importantly, these kits will include some type of a pressure gauge.
This acts as the display, allowing you to see exactly what kind of pressure you are dealing with. For diesel engines, these gauges typically go up to 1000 psi.
Along with the gauge itself, most kits will come with a set of adapters that allow you to fit the tester to a wide variety of engines. This is especially useful since you don’t have to go out searching for the specific connection to suit your needs.
What is the Best Diesel Compression Tester?
The best diesel compression tester is the Mityvac MV5532 Digital. This test kit comes with everything that you need to run diagnostics on your diesel engine and is incredibly accurate. Not only is this device incredibly reliable, it is also very easy to operate.
Included in this package is the digital pressure gauge, five hoses of varying lengths, and additional adapters.
Since there are so many adapters available, Mityvac has ensured that this is the only diesel compression test kit that you will ever need to buy. Also, the durable case that it all comes helps to keep everything organized and makes the entire kit extremely portable.
Thanks to its digital display, the pressure gauge that is included with this test kit is very easy to use. You are able to quickly assess the pressure reading and move onto the next cylinder. The precision that this type of pressure gauge provides simply cannot be beaten.
Besides, we have outlined five best compression testers you can buy for your diesel engine.
Comparing The Top 5 Diesel Compression Testers
|Mityvac MV5532 Digital|
|OTC 5021 Universal Diesel Engine Compression Gauge|
|14 Piece Diesel Compression Tester Set for Cars, Trucks, Tractors|
|PMD Products Diesel Engine Compression Cylinder Pressure Tester Gauge Kit 0-1000psi TU-15|
|Laser 4510 Diesel Engine Compression Test Kit|
1. Mityvac MV5532 Digital – The Most Accurate Test Kit
With this testing kit, you get a digital screen that narrows down the pressure reading to one decimal place and wants to be the only kit you will ever buy. The MV5532 reduces the hassle and stress that comes with most kits as it is well equipped with five rubber pressure hoses of varying lengths and lengthy adapters.
If it’s your first time using a compression tester, you will definitely appreciate the ease of use and the instruction manual that comes with step by step directions. The highly durable material coupled with the hard case prolong the lifespan of this kit even further.
- Digital gauge delivers accurate readouts
- Comes with a range of adapters
- Comes with a storage case
- Not ideal for 2-stroke engines
- Needs calibrating
2. OTC 5021 Universal Diesel Engine Compression Gauge – The Universal Diesel Engine Tester
The hose end of the gauge has a check valve button included and a quick disconnect fitting. Amongst the included accessories is a much-needed straight and 45-degree hose connectors that enable you to reach the spark plugs.
- Measures up to 1000 PSI meaning it can work on any diesel engine.
- Includes some handy accessories like the 45-degree hose
- Does not include a carry case
- Does not come with an adapter
3. 14 Piece Diesel Compression Tester Set for Cars, Trucks, Tractors – Best Professional Kit
In addition to having numerous adapters, this tester comes with a hassle-free swivel-end and quick–coupler that allows you to connect and disconnect adapters. The gauge has a release valve included, and the hose is 14.5 inches long to ensure that it reaches the concealed parts in the engine bay.
This compression tester can go up to 1000 PSI, which is the recommended pressure level for diesel engine tester kits.
- Comes with multiple adapters
- Superior quality materials and is built to last
- The hose is not very flexible
4. PMD Products Diesel Engine Compression Cylinder Pressure Tester Gauge Kit 0-1000psi TU-15 – The Durable Kit
No products found.The PMD Diesel Engine Compression Cylinder Pressure Tester Gauge Kit is a 12-piece tester that scales from 0 to 1000 PSI. The tester kit has a readable 2.5-inch gauge with a push button air release.
The most intriguing aspect about this particular kit is the rugged built quality of every facet that comes in the case. The 15-inch adapter is made of flexible and equally durable material that enables it to reach the hidden spark plugs.
Like most professional kits, this one comes with 12 adapter pieces that enable you to work with a variety of car models without necessarily buying extra adapters.
- Crafted from high quality materials
- Come with a hard case to keep you organizes
- Features a variety of adapters
- Quite pricey
5. Laser 4510 Diesel Engine Compression Test Kit – The Versatile Kit
Its high compatibility makes it a user-friendly tool kit to take care of all internal issues in your vehicles efficiently. This portable kit boasts its blue-colored hardened case to keep all the instruments, including spacers, clamps, claws, adapters, plugs, etc., safely in various molded sections.
That way, you can easily carry the kit around with you and use it for testing leakages in engines uninterruptedly. For beginners, Laser even adds an instruction manual so that people know how to use each tool present in the kit without any issues.
- Robust, hardened carrying case
- Suitable for all modern vehicle engines
- Boasts a broad 2.5″ diameter gauge
- The product is from outside the USA.
- The seller is new on the online platform.
How to Use a Diesel Compression Tester
Operating a diesel compression tester is a lot easier than it may seem. However, it should also be noted that the exact process may differ depending on the engine, so keep that in mind. Further ahead we will outline some of the basic steps when using a compression tester.
- Step 1 – Disable fuel injection and remove all glow plugs. This is for safety and will help to reduce any compression resistance.
- Step 2 – Find the correct adapter for your specific engine. Most kits will come with a variety of different adapters, so you shouldn’t have any trouble finding one that works for you. Make sure to do your research and get a test kit that you know is compatible with your truck.
- Step 3 – Thread the adapter into the glow plug hole and attach the pressure gauge. Be very careful and double check before going any further, as any loose-fitting adapter could be very dangerous when placed under high pressure.
- Step 4 – Activate the starter with a test jumper. Since we already disabled the ignition, the engine will not start. Allow the engine to turn over a few times and record the final pressure that you find on the gauge. Repeat this process for every cylinder.
Factors to Consider When Buying the Best Diesel Compression Testers
Before we look at what you should consider when buying a diesel engine compression tester, it is paramount that you learn the testing procedures and how the compression testers work.
The process is fairly simple, and you should be able to conduct this on your own rather than taking your car to the mechanic.
How do diesel compression testers work?
First things first, the engine operation involves the piston which is used to compress a mixture of fuel and air in the combustion chamber. In this very chamber, air is drawn from the outside and fuel from the fuel pump.
The mixture is normally put under high pressure from the pistons upward movement and the park plug release a spark that causes the mixture to explode. This, in turn, drives the piston down thus providing power for the engine.
Problems normally arise when the compression is off. Very low compression will cause the engine to work inefficiently as the power drawn would be minimal, and will therefore have to work for longer to generate the same amount of energy.
The compression testers now hook onto these spark plugs ports in order to measure the level of compression. The compression measurement should be taken when you crank up the engine three to four times in order to get the full compression.
If you are looking for tire safety you should consider buying the right TPMS tools. Using a TPMS helps to maintain good tire health, fuel efficiency, and improve vehicle safety.
Although this varies slightly from one diesel engine to another, the general procedure involves:
- Disabling the fuel injection: This can either be done by removing the fuel fuse or disconnecting the fuel supply altogether.
- Secondly, removing all the glow plugs; this is to reduce the emanating compression pressure.
- Using the correct adapter from the compression tester, thread it into the glow plug hole. Ensure that the gauge attaches to the plughole through the adapter firmly.
- Make one last check to verify that the ignition is disabled so that the engine does not start.
- Activate the starter directly by use of a test jumper.
- Crank the engine 4-5 revolutions in order to get the maximum compression.
- Read the PSI figure on the gauge straight to prevent parallax error and record it.
- Repeat this for all the other cylinders and compare compression pressures.
If you are still having a torrid time choosing the best diesel compressor for your engine, the following guideline will lead to the right choice should you choose to pick a compressor outside the five mentioned above.
Engine Compression Gauge
The compression gauge is the calibrated face where you take your readings from after cranking up your engine during testing. Most compression kit gauges are dial or analog in nature, but you will find a few that are digital. One good example of a digital gauge kit is the Mityvac MV5532 Digital.
One major advantage that comes with a digital gauge is increased readability and accuracy in measurement. To be precise, a digital gauge can narrow down a measurement to the nearest .0.
A good compression test kit should have a number of adapters in order to fit different car models. Make sure to go for a kit that has a full assortment of adapters to fit both the standard plug and the lesser common sizes as well.
The adapters included are just as good as their length. The spark plugs can be quite cumbersome to reach, and the testing process will be more enjoyable with a 15-inch long adapter. The most common adapters measure 10mm, 12 mm, 14 mm, or 18 mm in width.
Because you are not an expert in mechanics and do not have the time to go through all the available options, it is wise to consult. The feedback from experts or users will help in evaluating the available options.
This will also help narrow down your options with the numerous compression testers out in the market.
Many models come with a hard case included. A hard case is better than no case as it helps you stay organized and quickly find the required adapters if need be.
The fact that you can store all parts in a single bag also means that they can easily be ported to the testing site.
With many compression tester kits, this is normally the hose and gauge. Other models come with a little bit more included. All in all, the included components have to be of good quality. Readability is increased with a 2.5 inch calibrated gauge that shows pressure in both PSI and kPa.
The hose is something that you will twist and turn frequently in order to reach the inaccessible engine bay. For durability go for a hose that has a steel casing to prevent the hose from being worn out or cut by engine parts.
Ease of Use
The good thing about the entire process of compression testing is that you can do it yourself. This erases the need to approach the neighborhood mechanic and also saves on a few coins.
Compression testing is a simple DIY project and is made easier with detailed instructions from the manufacturer.
When purchasing a compression tester make sure to look for one that can withstand use and abuse over time. The components should be durable enough to serve you for over one year at best.
From the hose fittings, adapters to the gauge itself they should be made from premium materials and be rugged enough to resist some damage from external forces.
This is perhaps the most important part of the entire compression assembly. Gauge is a display face that shows the pressure readings from the compression chamber.
A faulty gauge is unusable, and it should, therefore, be large enough for easy legibility and most importantly, be accurate.
Moving parts can inadvertently break down during use. Although you will be buying a quality compression tester, do ensure that the manufacturer gives you comprehensive warranty coverage.
This only serves to show that the product sold is of high quality and the manufacturer is positive about it. The advantage of a warranty is that the broken parts can be repaired without charges should you mess up or it breaks in your hands.
Ready To Buy The Best Diesel Compression Tester?
So there you are, a breakdown of the five best compression testers you can find for your diesel engine. The problem with compression kits is that there are so many that you may not know where to begin.
For optimal performance, find a tester that is made of quality materials and is accurate. If you have more than one vehicle or you might want to use a diesel engine compression tester kit with another vehicle, then having multiple adapters is always a plus.
If selecting one is too much for you, all the five above are solid options that will evaluate and help give your engine a clean bill of health.
Please let us know which of the five testers you opted for. Share any good or bad experiences you might have had as well. While you’re here, check out our latest guide for top rated serpentine belts. And, take a look at our piston ring compressors review guide.
Finally, if you are using diesel compression tester consider buying fuel injector cleaning kits. They keep the fueling system as clean as it can get, removing any obstructions from the channels.
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