When the engine in an old sports utility vehicle (SUV) started knocking, the owner answered with an engine teardown. The source of the knock, some worn-out bearings between the connecting rods and the crankshaft, could be fixed. The project needed new parts, the right tools, and some automotive know-how.
The SUV’s owner, a former auto mechanic, bought a remanufactured crankshaft from a local auto parts store. The crankshaft came with journal bearings, but required removing the cylinder heads and pistons. So the owner of the 1999 GMC Jimmy bought some new piston rings and engine gaskets, too.
To hone the engine’s cylinders, the mechanic used the BRM Flex-Hone® tool.
Flexible Cylinder Honing
Flex-Hone® tools impart the ideal surface finish to the walls of engine cylinders. Made in the USA by Brush Research Manufacturing (BRM), these engine hones impart a series of oil-retaining grooves to promote optimum lubrication. In used engines, Flex-Hone® tools break the “glaze” – an overly smooth surface finish – that forms on cylinder walls because of the reciprocating movement of the pistons.
“I had to buy a Flex-Hone”, the GMC Jimmy owner’s explained, “to create the proper scratch pattern on the cylinder walls”. Known also as a ball hone, the BRM Flex-Hone® features abrasive globules or balls that are permanently laminated to flexible nylon filaments. With their low-temperature, low-pressure abrading process, BRM ball hones are great for cylinder deglazing and create a crosshatch pattern without excessive material removal.
BRM ball hones are also self-centering to the bore and self-compensating for wear. Built with a metal-wire stem, the Flex-Hone® can mount in a hand-held power tool like the electric drill that the GMC Jimmy owner used. The Flex-Hone® Resource Guide explain how to select and use ball hones for engine rebuilds and applications such as cross-hole deburring.
Plateau Finishing
In addition to imparting a series of oil-retaining grooves, Flex-Hone® tools reduce raised areas or peaks to a uniform height. This plateau finish promotes proper piston ring seating and sealing. Without a plateau finish, piston rings and engine cylinders may experience unnecessary wear as the piston rings move up-and-down, shearing off the tallest peaks.
Engine cylinders with a plateau finish support engine break-in and provide increased compression for improved power and performance. Plateau honing also helps to reduce reduced engine oil blow-by, oil consumption, and emissions. To learn more about the advantages of flexible honing and how to select and use BRM Flex-Hone® tools, download the Flex-Hone® Resource Guide.
