Heavy Duty Compression Testers for Trucks: Top Picks
For most heavy duty truck owners, the OTC 5605 is the top choice because it offers a robust gauge and long hose that reaches deep into diesel engine cylinders, but it lacks a quick-connect adapter set, requiring manual threading.
Checking compression on a heavy duty truck engine demands a tester that can handle high pressures and reach awkward cylinder positions. A flimsy kit will give false readings or break under load.
We compared top-rated compression testers designed for trucks, focusing on gauge quality, hose flexibility, adapter coverage, and whether they suit both gas and diesel engines.
What matters most
The best picks, ranked
OTC 5605 Heavy Duty Compression Tester
This kit includes a heavy duty gauge with a large dial and a 24 inch hose that reaches deep into diesel cylinders. The adapters fit most diesel glow plug threads and gas spark plug sizes.
Pros
- Accurate readings on high pressure diesel engines
- Long hose for hard to reach cylinders
- Solid metal construction
Cons
- No quick connect fittings
- Case is basic
Mityvac MV5530 Compression Tester Kit
This kit covers a wide range of gasoline engines with a durable push button release valve and color coded gauge. It comes with a flexible hose and multiple spark plug adapters.
Pros
- Affordable price point
- Easy to read color coded dial
- Quick release valve for fast testing
Cons
- Not for diesel high compression
- Hose is shorter
OTC 5606 Compression Tester Adapter Kit
This adapter kit pairs with the OTC 5605 to provide extra diesel adapters and extensions. It is useful for shops that need to test various heavy duty engines.
Pros
- Expands capability of existing tester
- Quality machined adapters
- Includes o rings
Cons
- Requires separate main kit
- Not a standalone tester
K Tool International 32970 Compression Tester
This affordable kit includes a flexible hose with quick connect couplers and a range of adapters for gas engines. The gauge is clear and has a rubber guard.
Pros
- Very low price
- Quick connect fittings save time
- Rubber guard protects gauge
Cons
- Not for diesel
- Hose may be stiff in cold weather
Powerbuilt 648492 Compression Tester Kit
This kit includes both a standard gauge and a diesel adapter set, making it suitable for many trucks. The push button release and flexible hose are convenient.
Pros
- Covers both gas and some diesel
- Durable blow mold case
- Good value
Cons
- Diesel adapter may not fit all glow plugs
- Gauge not as large
AEM 30-4100 Digital Compression Tester
This digital tester connects to a smartphone app to display compression and RPM data. It is designed for gas engines and gives highly accurate readings.
Pros
- Precise digital readings
- Logs data for analysis
- Easy to read on phone
Cons
- Requires smartphone
- Not for diesel high pressure
Continental 33700 Compression Tester
This professional kit offers a heavy duty gauge and a wide array of adapters for both gas and diesel engines. It comes in a sturdy metal case with a 24 inch hose.
Pros
- Comprehensive adapter set
- High quality gauge
- Metal case for protection
Cons
- Higher price
- Bulky to carry
The lineup, side by side
| # | Model | Gauge Range | Best for | Score | Price |
|---|---|---|---|---|---|
| 1 | OTC 5605 Heavy Duty Compression Tester | 0 to 1000 PSI | Diesel truck engines with deep recessed glow plugs | 9.4 | Check price |
| 2 | Mityvac MV5530 Compression Tester Kit | 0 to 300 PSI | Gas truck engines (gasoline) | 9.1 | Check price |
| 3 | OTC 5606 Compression Tester Adapter Kit | Diesel glow plug | Adding diesel capability to existing gas tester | 8.9 | Check price |
| 4 | K Tool International 32970 Compression Tester | 0 to 300 PSI | Budget conscious DIY truck owners | 8.7 | Check price |
| 5 | Powerbuilt 648492 Compression Tester Kit | 0 to 300 PSI | Gas and light diesel truck engines | 8.8 | Check price |
| 6 | AEM 30-4100 Digital Compression Tester | Digital on app | Data logging and precise digital readings | 9.0 | Check price |
| 7 | Continental 33700 Compression Tester | 0 to 1000 PSI | Professional mechanics needing a complete kit | 9.2 | Check price |
Good to know
What is a compression tester used for on a truck?
It measures the cylinder pressure to assess engine mechanical condition. Low compression in a cylinder can indicate worn rings, valves, or head gasket issues.
Can I use a gas compression tester on a diesel truck?
Usually no, because diesel engines produce much higher compression pressures, often exceeding 400 PSI. Using a gas tester could damage it. You need a tester rated for diesel pressures.
How do I know what adapter to use?
Check your truck’s service manual for the spark plug or glow plug thread size. Most kits include adapters for common sizes like 14mm and 18mm. For diesel, the glow plug thread may be 10mm, 12mm, or 14mm.
What is a good compression reading for a truck engine?
For gas engines, readings above 120 PSI are typical, with variations under 10% between cylinders. For diesel engines, readings can be 300 to 500 PSI or higher, depending on the engine.
How often should I do a compression test?
Only when you suspect engine problems like misfires, loss of power, or excessive oil consumption. It is not a routine maintenance item.
Can I leave the compression tester in the cylinder while cranking?
Yes, you must keep it connected while cranking to get the maximum reading. The gauge has a one way valve that holds the pressure until you release it.
What is the difference between a compression tester and a leak down tester?
A compression tester measures the pressure generated during cranking. A leak down tester applies external air pressure to a cylinder at TDC and measures the leakage percentage. Leak down testing helps pinpoint the source of compression loss.
Are digital compression testers more accurate?
Digital testers can be more accurate and easier to read, but they are often limited to gas engines. They also require batteries and may not be as rugged as analog gauges.
How long does a compression test take?
It can take 30 minutes to an hour for a typical truck engine, depending on accessibility and the number of cylinders. Removing and reinstalling components takes the most time.
Can I test compression on a running engine?
No, compression testing is done on a non running engine with the starter cranking it. Never connect a compression tester to a running engine.
The bottom line
For most truck owners, the OTC 5605 is the best investment because it handles both diesel and gas engines with a rugged build and long hose. If you only work on gas trucks, the Mityvac MV5530 offers great value and accuracy without the extra cost of diesel capability.
Tony Russo
Tony trained as an automotive technician and spent years in service and parts retail before moving into writing. He focuses on garage tools, car care products and accessories from a hands-on maintenance perspective.
