5140118-79 Cylinder Gasket

The 5140118-79 is an OEM cylinder gasket designed to seal the interface between the air compressor cylinder and the valve plate assembly. This gasket occupies a critical position in the compression stack, preventing pressurized air from bypassing the valve plate and escaping into the crankcase. It is a genuine OEM replacement part manufactured for use across a range of oil-lubricated, single-stage air compressor pumps produced under the DeWalt, DeVilbiss, Porter Cable, and Craftsman brands.

Over time, cylinder gaskets are subject to compression set, heat cycling, and oil exposure, all of which can cause the material to thin, harden, or crack. A degraded cylinder gasket typically presents as a compressor that struggles to build pressure, leaks air at the cylinder head, or loses compression efficiency. Replacing this gasket restores the air-tight seal necessary for proper pump operation.

Specifications

• Position: Between cylinder and valve plate assembly
• OEM Status: Genuine OEM replacement part

Installation Notes

Before servicing the cylinder head assembly, unplug or disconnect the compressor from its power source and fully bleed air pressure from the tank. When removing the cylinder head, inspect the machined sealing surface on both the cylinder and the valve plate for damage, scoring, or debris. The sealing ridge cast into the mating surfaces must remain intact and undamaged to ensure a proper seal with the new gasket — use care when scraping away the old gasket material, particularly on aluminum surfaces. After installing the new gasket, torque the head bolts evenly by working in an opposing pattern to avoid uneven seating. Periodically re-checking head bolt torque after the first several hours of operation is recommended practice.

This gasket is commonly replaced together with part number 5140118-80 (valve plate-to-head gasket) when fully disassembling the cylinder head. Replacing both gaskets during the same service interval is good maintenance practice.