Friday, November 24, 2006

VW - Paint Your Engine

Recent comments make it clear a lot of folks are not aware of the benefits of painting their engine. The basic reason for doing so is preservation. When fitted with a full-flow oil filtration system the VW flat fours can deliver 150,000 miles or more of service before the lower end requires overhaul. Indeed, when fitted with hydraulic cam followers and other modern innovations such as electronic ignition, it’s not uncommon for a properly assembled engine to deliver 100,000 miles of service without requiring any form of repair.

A light coat of flat black paint on the magnesium-alloy crankcase not only protects it from corrosion, it enhances the heat-flow characteristics of the surface. The cast iron cylinders benefit even more, although they are more difficult to paint. The trick is to get the paint right down into the bottom of the fins. To do so calls for the use of a suitable brush, made by cutting off half the bristles from a small (1/2") paint brush; not an artists brush, the regular sort does fine. You must use a brush instead of spray because by the time you’ve sprayed enough paint to reach the bottom, you’ve flooded the upper part of the fins and made an unholy mess. So start with the brush, take your time and give your new jugs at least a day to dry before handling them.

The barrels on high time engines, especially those operated in cold climates where corrosive substances are used for snow removal, are often found to have virtually no fins at all when the engine is torn down for rebuild. Ions of the corrosive material, common rock salt in most cases, attach readily to unprotected cast iron, and once attached are impossible to remove without boiling with a ‘getter.’ This means that once the corrosive ion finds a home on your cast iron cylinders, the corrosive action will continue year round, thanks to water vapor in the air.

Rusty or corroded metal makes a fine heat insulator, as every weldor knows. A few ounces of paint judiciously applied prior to assembling your engine is not only the mark of an experienced mechanic, it is one of those performance-enhancing tricks so simple it is often overlooked. But in the long term it means greater service life and lower operating costs.

Before you succumb to the conventional wisdom that painting is an unnecessary luxury, drop by any airport and examine the engines that inspired the original Volkswagen engineers. Aircraft engines are painted as a matter of course, although such niceties were ignored with the VW in the interest of economy. The original idea was to replace rather than overhaul the engine, and to replace it fairly often -- typically, at something less than 100,000 km (62,000 miles). Alas, this option is no longer practical in todays economic climate.

-Bob Hoover

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