Disassembly/Inspection and Service Measuring Piston-to-Bore Clearance Piston Detail NOTE: Do not use a feeler gauge to measure piston-to- bore clearance–it will yield inaccurate measurements. Always use a micrometer. Before installing piston into cylinder bore, it is necessary that clearance be accurately checked. This step is often overlooked, and if clearances are not within specifi cations, engine failure will usually result. Use following procedure to accurately measure piston- to-bore clearance: 1. Use a micrometer and measure diameter of piston above bottom of piston skirt and perpendicular to piston pin. 2.
Use an inside micrometer, telescoping gauge, or bore gauge and measure cylinder bore. Take measurement approximately 63.5 mm (2.5 in.) below top of bore and perpendicular to piston pin. 3. Piston-to-bore clearance is difference between bore diameter and piston diameter (step 2 minus step 1). 58 KohlerEngines.com 66 690 01 Rev. C A Style A B Style B Model Dimension A Dimension B LH630/LH640 6 mm (0.2362 i n.) -- LH685/LH690 6 mm (0.2362 i n.) 13 mm (0.5118 in.) LH750/LH755 6 mm (0.2362 i n.) 6 mm (0.2362 in.)