National Oil & Lube News

February 2017

Digital issues of National Oil & Lube News, the trade magazine for the preventive maintenance industry

Issue link:

Contents of this Issue


Page 55 of 67

56 NOLN | VIEWPOINT Automotive Maintenance e primary objective of thorough inspections and system main- tenance is to prevent some unnecessary and costly repair expense for the customer. System neglect can result in hundreds of dollars in repair costs that may have been circumvented by performing some basic maintenance. Servicing the Brake System Most technicians perform a thorough brake inspection including friction wear and abnormal wear patterns, loose or missing hard- ware, corrosion and excessively worn or damaged rotors. Unfor- tunately, few take the time or consideration to flush and restore the lifeblood of the brake system — the brake fluid. Bad things happen to the fluid, and it can occur in a short period of time. Contaminated fluid can result in pedal fade or total brake system failure. Costly anti-lock brake system components can also be per- manently damaged. Brake fluid is hygroscopic and will absorb moisture through the brake hoses, seals and the master cylinder cover. Within a 12 month period, the system can absorb 2 percent of its volume in moisture. A DOT 3 brake fluid with a 3-percent moisture accu- mulation will experience a 25-percent drop in the boiling point. When this occurs, the system may continue to function normally during normal braking, but one may encounter brake pedal fade during aggressive braking conditions. e DOT 4 brake fluid has a higher boiling point than the DOT 3 fluid, but its wet boiling point may drop more rapidly than the DOT 3 fluid when subjected to moisture. Both the DOT 3 and DOT 4 fluids are comprised of mixtures of glycols and glycol ethers. Additionally, the DOT 4 flu- id contains borate esters, which increase the dry and wet boiling points. While both fluids are compatible with the braking systems and internal components, they respond differently when subject- ed to moisture. Systems filled with DOT 4 fluid will require more frequent flushes. Moisture affects the corrosion inhibitors in the brake fluid, thereby promoting corrosion and failed brake system components. Within 36 months, 91 percent of the corrosion in- hibitors in the fluid may be lost. DOT 5 fluid is a silicone fluid, and it is not compatible with other fluids. It is not hygroscopic, there- fore, any moisture can pool, promoting corrosion. at can lead to a catastrophic component failure, especially with anti-lock brake system components. Silicone fluid can damage seals because of the lack of additives that lubricate the rubber components. Sili- cone-based fluids are compressible, causing a soft or spongy pedal sensation. Brake fluid maintenance is imperative. Major System Contamination Vehicles placed in storage or not driven frequently can encoun- ter major contamination, too. Let's consider a 1969 Corvette that received a body-off frame restoration, was driven occasionally over a two-year period and then placed in storage for 25 years. e braking system on this vehicle is a four-wheel disc four-piston caliper assembly. e following illustrations reflect what can happen to a brak- ing system, especially when the vehicle encounters long periods of storage with no maintenance/fluid flushes. e pistons were heavily corroded (see Fig.1). e calipers revealed no evidence of fluid; instead they were contaminated with a rusty powdery resi- due (Fig.2) that had the appearance and texture of sand and grav- el. When the vehicle went through the major restoration, DOT 5 silicone brake fluid was installed, which is not recommended. e repair required a total system replacement, which included brake lines, hoses, master cylinder, proportioning valve, calipers, pis- tons and seals. While this system failure was an extreme example, it illustrates how bad things can happen to the braking system, even when the vehicle is not driven on a daily basis, when brake fluid flushes are not performed. Contamination conditions usually encompass caliper bores that contain a sludge or milky deposit due to the hygroscopic action of the brake fluid. When these conditions occur, brake pedal fade or a total loss of pedal can occur during an aggressive braking con- dition. Brake fluid flushes are recommended every two years or 24,000 miles. Always refer to the manufacturer's recommenda- tion for fluid replacement. Installing the Correct Oil Filter With most vehicle manufacturers offering extended service in- tervals, nothing is more critical than selecting the correct oil fil- ter and lubricant for the application. Lubricants and filters you have relied on in the past are often not compatible with today's technology and may result in engine noise or internal component failure. Changes in bearing technology and variable valve timing, which allows continuous camshaft adjustments to advance or re- tard the timing to control emissions and increase performance and fuel economy, makes filter and lubricant selection critical. Make certain your filter selection is from a trusted source. It is impossible to determine the quality of the filter by the physical dimensions and thread size. e filtration of the media is deter- mined by special equipment and testing procedures. Filter bypass settings are critical, especially with newer engine technology and higher oil pressure differentials across the filter. is requires a filter with a higher bypass setting to prevent un- filtered oil from damaging the bearings and internal engine com- ponents. Neglected Service: The Results Can Be Costly by Larry Hammer

Articles in this issue

Links on this page

view archives of National Oil & Lube News - February 2017