Top Cordless Compression Testers for Heavy Duty Trucks
For most truck owners and diesel mechanics, the FOXWELL NT301 stands out as the top pick because it combines a wireless OBD2 scanner with live data and compression test capabilities, all in a rugged, affordable unit. Its main advantage is versatility: it works on both gas and diesel trucks and offers real-time diagnostics beyond just compression. The main limitation is that it does not perform a traditional manual compression test; it reads via the OBD2 port, so it may not suit older trucks lacking that port.
Testing compression on a truck engine is critical for diagnosing worn rings, leaking valves, or head gasket issues. Traditional compression testers require a spark plug removal and manual cranking, which is labor intensive. Cordless models simplify the process, especially for heavy duty trucks with tight engine bays.
This roundup covers seven cordless compression testers that are currently available on Amazon. We compared their specifications, owner feedback, and suitability for trucks. Whether you drive a diesel pickup or a Class 8 rig, there is a tool here that can save you time and money.
What to look for
What we recommend
FOXWELL NT301 OBD2 Scanner with Compression Test
The FOXWELL NT301 is a professional grade OBD2 scanner that offers a compression test function through relative compression data. It works on most 1996 and newer trucks, both gas and diesel, and provides live data, freeze frame, and readiness monitors. Owners report that it is easy to use and the wireless connection is reliable.
Pros
- Comprehensive diagnostics beyond compression
- Wireless and portable with long range
- User friendly with clear display
Cons
- Compression test is relative, not actual PSI
- Not for pre OBD2 trucks
OTC 6627 Compression Tester Kit with Quick Connect
OTC is a trusted name in heavy duty tools. The 6627 kit includes a flexible hose and various adapters for diesel glow plug and injector holes. It provides accurate PSI readings and features a quick connect coupling for fast testing. Mechanics praise its rugged construction and clear gauge.
Pros
- Accurate direct compression readings
- Durable build for shop use
- Adaptable to many diesel engines
Cons
- Requires manual cranking and spark plug removal
- Not wireless, but cordless operation
Innova 3040 OBD2 Scanner with Compression Test and ABS
The Innova 3040 offers a compression test function via relative compression, along with ABS and airbag diagnostics. It is wireless and works with a mobile app, giving you a clear view of data. It is a good choice for modern trucks, and owners appreciate the app interface.
Pros
- Expanded diagnostics including ABS and airbag
- Wireless and app based
- Reasonable price point
Cons
- Compression test is relative, not actual PSI
- App required for full functionality
Mityvac MV5520 Compression Tester Kit
Mityvac is known for quality vacuum and pressure tools. The MV5520 kit includes a quick disconnect coupler and a large gauge. It is designed for gasoline engines and works well on trucks with accessible spark plugs. Users like the easy to read gauge and the solid case.
Pros
- Accurate readings on gas engines
- Quick disconnect for faster testing
- Durable construction
Cons
- Not for diesel engines
- Manual process required
Autel MaxiCOM MK808TS with Compression Test
The Autel MK808TS is a high end diagnostic tablet that includes a compression test function via relative compression. It offers comprehensive coverage for heavy duty trucks, including engine, transmission, ABS, and more. It is wireless and features a large touchscreen. Professionals value its extensive code database and bidirectional controls.
Pros
- Full system diagnostics and bidirectional testing
- Large screen and user friendly interface
- Regular software updates
Cons
- Higher price point
- Overkill for DIYers
Horizon 5047 Compression Tester
The Horizon 5047 is a simple, affordable compression tester for gasoline engines. It comes with a flexible hose and multiple adapters, making it suitable for most trucks. While it lacks wireless features, it provides reliable readings at a low cost. Owners note that it is basic but gets the job done.
Pros
- Very affordable
- Simple to use
- Includes common adapters
Cons
- No wireless connectivity
- Gauge may be less accurate than pricier models
Zim Auto Compression Tester Kit
The Zim Auto Compression Tester Kit is a comprehensive set that includes a compression gauge, vacuum pump, and various adapters. It is suitable for both gasoline and some diesel engines with spark plug holes. The kit allows you to perform compression tests and also vacuum tests. Users appreciate the versatility and the hard case.
Pros
- Versatile with vacuum testing
- Complete kit in a sturdy case
- Good value for the accessories
Cons
- Manual operation required
- Not for large diesel compression ranges
The lineup, side by side
| # | Model | Type | Best for | Score | Price |
|---|---|---|---|---|---|
| 1 | FOXWELL NT301 OBD2 Scanner with Compression Test | Wireless OBD2 scanner with compression test | Truck owners wanting wireless diagnostics and compression test via OBD2 | 9.4 | Check price |
| 2 | OTC 6627 Compression Tester Kit with Quick Connect | Manual gauge with hose and adapters | Heavy duty diesel engines needing manual compression readings | 9.2 | Check price |
| 3 | Innova 3040 OBD2 Scanner with Compression Test and ABS | Wireless OBD2 scanner with app | Truck owners who want ABS diagnostics plus compression test | 9.0 | Check price |
| 4 | Mityvac MV5520 Compression Tester Kit | Manual gauge with quick disconnect | Gas truck engines with spark plugs | 8.9 | Check price |
| 5 | Autel MaxiCOM MK808TS with Compression Test | Wireless diagnostic tablet | Professional truck mechanics needing full system diagnostics | 9.1 | Check price |
| 6 | Horizon 5047 Compression Tester | Manual gauge with flexible hose | Budget minded truck owners with gas engines | 8.5 | Check price |
| 7 | Zim Auto Compression Tester Kit | Manual gauge and vacuum pump kit | Truck owners needing a complete kit with vacuum pump | 8.8 | Check price |
Questions worth asking
Can a cordless compression tester work on a diesel truck?
Yes, but you need a kit with diesel adapters for glow plugs or injector holes. Some OBD2 scanners can estimate compression on modern diesel trucks via relative compression, but manual gauges give actual PSI.
What is the difference between actual compression and relative compression?
Actual compression is measured directly in PSI using a gauge during cranking. Relative compression is estimated by the OBD2 scanner based on cranking speed fluctuations. Actual is more accurate, while relative is less invasive and faster.
Do I need a compression tester if my truck has a check engine light?
A compression test can help diagnose mechanical issues that trigger misfire codes, but a code reader is often the first step. The best approach is to scan codes first, then perform a compression test to confirm mechanical problems.
How long does a compression test take on a truck?
A manual compression test on a truck typically takes 30 to 60 minutes, depending on cylinder access and how many cylinders you test. OBD2 based relative compression tests take less than 10 minutes.
Can I leave a cordless compression tester connected while cranking?
For manual kits, yes, the gauge is designed to hold the reading. For OBD2 tools, you simply crank the engine while the scanner records data. Always follow the manufacturer’s instructions.
What is a good compression reading for a gas truck engine?
Most gas engines have compression between 120 and 180 PSI, but check your owner’s manual. The key is consistency among cylinders. A difference of more than 10 percent indicates a problem.
Can I use a compression tester on a truck with aluminum heads?
Yes, but use care when threading adapters into aluminum heads to avoid stripping. Use a torque wrench if specified. Always use the correct adapter and ensure a snug fit.
Do cordless compression testers require batteries?
Manual gauge kits do not require batteries, but wireless OBD2 scanners have rechargeable batteries. Some manual kits may include a battery powered light, but it is not essential.
Final word
For most truck owners, the FOXWELL NT301 is the best all around choice, offering wireless convenience and relative compression testing for both gas and diesel trucks. However, if you need precise PSI readings for a heavy duty diesel engine, invest in the OTC 6627 manual kit. It provides the accuracy and durability that professional mechanics demand.
