A cylinder liner has to stand slightly proud of the block deck so the head gasket seals. Too little protrusion leaks coolant; too much cracks the deck. Use this worksheet to record four readings per liner, the shims you fitted and the final result - one sheet per engine.
How to measure liner protrusion
- Fit the new liner with its O-rings and shims into a clean, dry bore.
- Place the protrusion gauge (or a straight edge and depth micrometer) across the block deck over the liner flange.
- Take a reading at four points 90° apart - the liner must sit square.
- Write every reading in the table below, then compare with the workshop manual for your engine.
- Adjust with liner shims until all four readings are within spec and within 0.02 mm of each other.
Spec ranges vary by engine. Typical diesel wet-liner protrusion is around 0.02-0.12 mm, but always confirm the exact figure in the engine workshop manual (Weichai WD615 / WP10 / WP12, Cummins 6BT / 6CT / L10, Yuchai YC4D / YC6108, Baudouin 4M / 6M).
Protrusion worksheet (4 readings per cylinder)
| Cylinder | Reading 1 | Reading 2 | Reading 3 | Reading 4 | Shim fitted | OK? |
| 1 | | | | | | |
| 2 | | | | | | |
| 3 | | | | | | |
| 4 | | | | | | |
| 5 | | | | | | |
| 6 | | | | | | |
Download the worksheet as CSV
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Tools and parts used
Frequently asked questions
Most diesel wet liners sit about 0.02-0.12 mm above the block deck, with all four readings within 0.02 mm of each other. Always confirm the exact figure in your engine workshop manual.
The head gasket cannot clamp the liner, so combustion gas and coolant cross the fire ring: coolant loss, white smoke and gasket failure follow.
The head gasket is crushed locally and the block deck can crack around the liner seat. Correct it with shims, never by machining the liner flange.
Every time a liner is fitted or replaced, and after any overheat. Record the readings - it makes the next rebuild much faster.