PROTON Cylinder Gauge (4-in-1 Digital Diagnostic System)
The Proton replaces four separate engine-diagnostic tools with one touchscreen unit — a digital compression tester, a cylinder leak-down tester, a pressure & vacuum gauge, and a top dead center (TDC) assistant. Every reading is logged automatically to the cylinder it came from, and the leak-down percentage is calculated for you the moment you dial in 100 PSI — no notepad, no dividing one analog gauge by another. A single chart screen puts every cylinder side by side so a weak one is obvious at a glance. Built for gasoline engines up to 8 cylinders, with multiple spark-plug adapters and quick-connect fittings included, and backed by a 5-year 100% full-coverage warranty with USA-based replacement.
Best for: independent repair shops and professional technicians running compression and leak-down as part of routine diagnosis; mobile mechanics who need one compact kit instead of four; engine builders and performance shops verifying cylinder sealing; and serious DIY mechanics chasing a misfire, a burnt valve, or a suspected head gasket.
What it diagnoses
- Worn or broken piston rings — low compression plus air escaping into the crankcase.
- Burnt or leaking valves — air escaping out the intake (intake valve) or the exhaust (exhaust valve).
- Blown head gaskets — two adjacent cylinders down together, bubbles in the coolant, or air crossing into the next cylinder.
- Poor cylinder sealing — scored bores, carbon on a valve seat, anything that costs a cylinder its seal.
- Vacuum and timing problems — low or unsteady manifold vacuum, restricted exhaust, and general vacuum leaks.
Four tests, one unit
- Digital compression test — thread the hose into a spark-plug hole, select the cylinder on screen, and crank. The peak reading is captured and logged to that cylinder automatically.
- Cylinder leak-down test — feed the sealed cylinder 100 PSI of shop air and the Proton calculates and displays the leak percentage. Where you hear the air escaping tells you which part failed.
- Pressure & vacuum gauge — read manifold vacuum on a running engine in inHg, kPa or PSI, with high and low modes and a live graph-over-time view that shows whether vacuum is steady or oscillating.
- Top dead center (TDC) assistant — find TDC by watching pressure and vacuum as you turn the crankshaft, instead of guessing with a screwdriver or hunting timing marks. Accurate TDC is what makes a leak-down number mean anything.
Specifications
| Feature | Detail |
|---|---|
| Tests performed | Compression · Cylinder leak-down · Pressure & vacuum · TDC location |
| Display | Digital touchscreen with on-screen test shortcuts and instructions |
| Sensors | Digital pressure and vacuum sensors for repeatable readings |
| Data logging | Automatic per cylinder; chart view compares all cylinders on one screen |
| Leak-down calculation | Automatic leak % at a 100 PSI reference input — no manual math |
| Vacuum units | inHg, kPa or PSI, switchable on the display |
| Vacuum modes | High / low range, plus live graph-over-time |
| Cylinders supported | Up to 8 cylinders, each logged and compared separately |
| Engine compatibility | Gasoline engines. Not for diesel engines. |
| Adapters | Multiple spark-plug adapters and quick-connect fittings included |
| Also required | Ratchet to turn the crankshaft (TDC / leak-down) · air compressor at 100 PSI (leak-down only) |
| Shipped weight & package | 4 lb · 15.5 × 11 × 2 in |
| Warranty | 5-year 100% full coverage — manufacturer and operational defects, USA-based fast replacement |
What's in the box
- Proton digital cylinder gauge, with the one-way valve and plunger (bleed) valve on the unit
- Cylinder hose that threads into the spark-plug hole
- Extension hose for hard-to-reach cylinders
- Engine cylinder adapters for a range of spark-plug threads and reaches
- Quick-connect fittings and accessories
Who it's for
Repair shops and professional technicians. Compression and leak-down are routine work, and the time cost is usually in the record-keeping, not the testing. Automatic per-cylinder logging and a single comparison screen cut the paperwork out of the job and make the result easier to show a customer.
Mobile mechanics. One compact case does the work of a compression tester, a leak-down tester, a vacuum gauge, and whatever you were using to find TDC.
Engine builders and performance shops. Leak percentage calculated to the same 100 PSI reference every time makes cylinder-to-cylinder and before/after comparisons meaningful.
DIY mechanics. If you're chasing a misfire, a rough idle, or a suspected head gasket, this tells you which cylinder is down and then which component is letting go — the two questions that decide whether an engine comes apart.
Digital vs. a traditional analog setup
Running the tests
Proton compared with a conventional analog compression gauge plus a separate dual-gauge leak-down tester.
Included
Available
Not available
| Capability | PROTON Cylinder Gauge | Analog compression + leak-down kit |
|---|---|---|
| Compression testing | Yes | Yes |
| Cylinder leak-down testing | Yes | Yes |
| Leak % calculated for you | YesAutomatic at 100 PSI | NoYou do the math |
| Readings logged per cylinder | YesAutomatic | NoPen and paper |
| All cylinders compared on one screen | Yes | No |
| Manifold vacuum testing | YesLive graph over time | NoSeparate gauge needed |
| TDC location assistance | YesBy pressure & vacuum | NoScrewdriver / timing marks |
| Switchable units (inHg / kPa / PSI) | Yes | No |
| Tools to buy and carry | OneSingle case | Three or fourPlus a way to find TDC |
Analog kits are proven, inexpensive, and need no charging — if you run a compression test twice a year, one is hard to beat on price. The Proton earns its place when you test often enough that the logging, the automatic leak math, and having one kit instead of four save real time.
Warranty and support
Every Proton is covered by a 5-year 100% full-coverage warranty against manufacturer and operational defects. AutoLine Pro is an American family-owned business, and support is USA-based — if a unit fails, we replace it, fast. Questions before you buy? Reach us through the contact form.
The Proton is designed for gasoline engines. Diesel compression testing requires higher-range gauges and injector or glow-plug-port adapters, and is not supported by this tool.
FAQs
Use this text to answer questions in as much detail as possible for your customers.
Use this text to answer questions in as much detail as possible for your customers.