A Better Way to Clean Oil Galleries
I’ve always used the standard long handled nylon bristle brushes dipped in solvent to scrub the oil galleries in blocks, heads and cranks before assembly. However, while cleaning a gun bore, it occurred to me that I didn’t really know how clean the galleries were actually getting in the engines that I build. The patches used in cleaning gun bores give a very definitive visual of exactly how clean the bore is. I decided to try this method of cleaning on the next engine that I built, which was a 1928 Dodge flathead four cylinder. I started by cleaning the block like I always do: thermally process in an oven, run through an airless shotblaster, wash twice in an aqueous jet washing machine (once before machining and then again after), and finally run a cleaning brush with solvent through each gallery several times. After this, I got the gun cleaning equipment out and ran patches soaked with the same solvent through the main gallery. The results can be seen in the attached picture. Obviously, my cleaning method was not actually getting the galleries clean! Up close inspection of the patches revealed rust, grime and small shiny metal particles that were not removed by my standard cleaning regimen. This junk would certainly make its way to the bearings, especially with modern detergent oils and higher than stock oil pressure. It takes a few more minutes than my old method, but now I know the galleries are actually getting clean. Gun cleaning rods, patch- es and brushes in a variety of sizes, (0.177 ̋ – 0.729 ̋ are commonly available, although you will need a couple of different cleaning rods to span that range) can be obtained from a local sporting goods store for very little expense.

Tony Smith
Gunsmith/Machinist/Engine Builder
Lewistown, MT
August, 2013