Plastigauge 101: How to Measure Engine Bearing Clearance the Right Way

Checking bearing oil clearance usually means choosing between an expensive set of micrometers and bore gauges, or a strip of plastic that costs almost nothing and takes five minutes. Plastigauge is that second option — and it’s still the standard method most automotive workshops and engine rebuilders reach for first.

What Is Plastigauge, and How Does It Work?

Plastigauge is a precision plastic gauging strip placed across a bearing surface and compressed, then compared to a reference chart to measure engine bearing clearance within its designated range. Instead of measuring the bore and the shaft separately and calculating the difference, the strip itself deforms by an amount proportional to the actual clearance — so the reading comes directly from the flattened width, with the mechanical variables already accounted for.

It’s used to check crankshaft bearing clearance, connecting rod bearing clearance, camshaft bearing clearance, main bearing clearance, and other precision bearing oil clearances during engine assembly, rebuilding, and maintenance.

How to Measure Bearing Clearance with Plastigauge

1. Clean both surfaces first. Oil, grease, or debris on the bearing or journal will distort the strip and throw off the reading.
2. Cut a strip to length. It should run most of the width of the bearing, positioned lengthwise along the journal — not across an oil hole.
3. Lay the strip in place, dry. No oil on the strip itself at this stage — it needs to compress cleanly against both surfaces.
4. Assemble and torque to spec, then remove — without rotating the shaft. Rotating the crank or shaft while the strip is compressed smears it and invalidates the reading.
5. Take the cap back off and recover the flattened strip. It will have spread to a width that corresponds to the clearance at that point.
6. Compare the flattened width to the printed scale on the strip’s wrapper. The scale reads the clearance directly — in inches or millimetres, depending on the wrapper.

Once read, discard the strip. It’s a single-use consumable — the same piece can’t be reused for a second check, even on the same bearing.

Choosing the Right Clearance Range

Plastigauge strips are graded by clearance range, and picking the wrong one is a common reason a reading comes out unreadable — if the actual clearance falls outside the strip’s range, the flattened width lands off the printed scale entirely. KHOKHAWALA TRADING LLC stocks four graded ranges, covering everything from tight precision clearances to wider ones:

If you’re unsure which range your expected clearance falls into, our team can help you pick the right one before you order.

Common Mistakes That Ruin a Reading

• Placing the strip over an oil hole. The strip needs continuous contact across the bearing surface — a gap over an oil hole gives a false, uneven reading.
• Rotating the shaft with the gauge compressed. Any rotation smears the strip sideways instead of a clean, even compression — the reading becomes meaningless.
• Using the wrong range for the expected clearance. If the real clearance falls outside the strip’s graded range, the flattened width won’t match anywhere on the printed scale.
• Trying to reuse a flattened strip. Once compressed and read, a strip is finished — always use a fresh piece for the next check.
• Skipping the cleaning step. Oil or debris on either surface changes how the strip compresses and skews the result.

The Classic PLA–PLD Strips

Alongside the graded Blue series above, we also stock the classic Plastigauge PLA, PLB, PLC, and PLD strips, plus a range from Clevite — all built on the same compress-and-compare principle, for workshops that already work with a specific product line.

Who Uses Plastigauge?

Plastigauge bearing clearance gauges are used across automotive repair workshops, diesel engine servicing, industrial maintenance, marine engineering, power generation, manufacturing plants, heavy equipment maintenance, and mechanical engineering — anywhere a bearing clearance needs to be checked without pulling out a full set of micrometers and bore gauges.

Sourcing Plastigauge in Dubai

Khokhawala Trading LLC has supplied genuine Plastigauge bearing clearance gauges, precision measuring instruments, and industrial tools in Dubai since 1989, stocked from Plastigauge and Clevite. Rated 4.8 on Google, based in Deira, Dubai, open 8:00 AM to 8:00 PM Monday to Saturday, with free delivery across Dubai on orders above 499 AED.