Marine Diesel Engine Cylinder Liner Overhaul Tool Upsized

By George Backwell at March 16, 2013 03:44
Filed Under: General, Marine Diesel Engines

Cylinder liners of both 4-stroke and 2-stroke engines show signs of wear and tear after extended use, regardless of the latest advances in lubricating oil and liner casting technologies. What's not quite so obvious is that when doing the consequent engine overhauls or engine repairs that involve cylinders, it is predictable that the liners will have to be deglazed and crosshatched. For cylinder deglazing jobs (plateauing as well) one industry standard tool is the compact, portable ball hone from Brush Research Manufacturing (BRM), who recently announced that its Flex-Hone® tool was available for ‘big bore’ marine diesel engines up to 40-inches in diameter.

'Big Bore' Cylinder Liner: Photo courtesy of Bright Hub Engineering

When a cylinder liner comes out of the factory, it will have a slight cross-hatch pattern honed into its surface, an increased roughness to help the liner surface to retain the lubricating oil needed to provide an evenly distributed oil film between the piston ring reversal points. If the surface becomes too smooth due to wear with glazing of the surface, the piston rings will more easily break the oil film, causing even more wear. Worse still, any excess oil will no longer be retained by the liner surface, and will burn off instead, causing an increase in lube oil consumption.

The BRM Tool
Widely known by its Flex-Hone® brand name®, the ball-style hone is a highly specialised abrasive tool that is instantly recognisable by its unique appearance. Featuring small, abrasive globules that are permanently mounted to flexible filaments, the product is a flexible, low-cost tool that is a favourite among mechanics and metal workers due to its cylinder deglazing, de-burring, edge blending and crosshatching capabilities.

Flex-Hone® tool: Image credit BRM

An Inexpensive Alternative to Air-Operated Equipment
The electrically operated flexible hone is an efficient alternative to air-operated equipment which must be lined up with the studs on the engine block. Not only does the ball hone set up much more quickly, but just a few passes up and down inside a cylinder liner accomplishes thorough deglazing as well as crosshatching. The Flex-Hone® tool's independently-suspended, abrasive globules both self-centre and self-align to the bore as well as compensate for wear, all of which facilitate close-tolerance finishing work.

Plateau Finishing for Piston Ring Seating
Wear on the liner is not evenly distributed – most of it occurs between the reversal points of the upper and lower piston rings –  and commonly scuffing marks are to be seen where the upper piston ring changes direction. The purpose of plateauing is to remove loose, cut, torn and folded material within the cylinder, create valleys and remove peaks that would otherwise damage rings or seals, and the Flex-Hone® is capable of that as well.

Although the Flex-Hone® is used for refurbishing cylinder liners, BRM (factory located in Los Angeles, California) say the tool is also quite versatile and adaptable to many applications where honing the inside of cylindrical shapes is needed, including cleaning pipe bores and valves on some pump designs.



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