Gary Goms, Author at UnderhoodService - Page 6 of 25
Ride Control Systems: Matching The Components To The Application

During the fall of 1989, when I was working as a mechanic for an off-road desert racing team, we raced the famous Mint 400 held in Las Vegas. By mid-race, our truck came into its pit stops with the shock absorbers so overheated that the polyurethane bushings were literally melting out of the shock mounts. Worse still, as the shock absorbers began to fail, so would the leaves in the truck’s leaf-spring suspension. Despite the suspension problems we experienced during the race, we were lucky enough to win our class. But the lessons I learned about the importance of matching the shock absorber to its application endure to this very day.

How Ride Height Affects Toe Angle

How can a mysterious case of tire wear occur in a perfectly aligned vehicle? It happens and the answers aren’t always simple. To better explain, let’s go back a few decades when I aligned a 1983 Mitsubishi rear-wheel drive (RWD) pickup, only to have it return a month later with a tire scuffing complaint. My conclusion was that many independent front suspensions often require a “custom alignment” to compensate for variations in ride height caused by uneven loading.

Diagnostic Dilemma: 1999 Dodge Dakota Intermittent Stall Complaints

Diagnosing intermittent stalling complaints is a challenging experience for any diagnostic technician because any number of electrical and mechanical failures can cause an engine to intermittently stall. Most of us immediately narrow this laundry list of potential failures down to the most common few, which include components like the crankshaft position sensor and electric fuel pump.

Contaminated Fuel Can Wreck Havoc On Fuel Delivery Systems

Although cases involving contaminated gasoline are relatively rare nowadays, they still occur. In many cases, the technician has replaced the fuel pump or mass air flow (MAF) sensor to address a P0171/P0174 “lean-condition” DTC with no result. In all likelihood, the technician didn’t consider the possibility that the vehicle’s fuel might be contaminated with E85 gasoline, diesel fuel, stale gasoline, or, to a lesser degree, sugar and water.

Diagnostic Solutions: Direct Fuel Injection Systems

For veteran technicians, it’s no wonder that the internal combustion engine (ICE) has been pronounced “dead” on more than one occasion. After having gone through the gas turbine craze during the early 1960s and the rotary engine fad of the 1970s, it comes as no surprise that we’re witnessing still another resurrection of the reciprocating internal combustion engine in the form of gasoline direct fuel injection.

Universal Joint Inspection And Replacement

In modern automotive architecture, universal joints are most commonly found on the rear axles of light trucks, SUVs and RWD passenger cars. While some low-angle joints are made with a rubber-compounded material, most modern universal joints are made of a steel cross connecting four trunnions containing lubricated needle bearings.

Diagnostic Solutions: Modern Spark Plug Diagnostics, The ‘Art And Science’ Of Reading Plugs

With the advent of electronic engine management systems, “reading” spark plugs has become something of a lost art. In the days of mechanical carburetors and distributors, the color and texture of the spark plug’s insulator could provide important information about the air/fuel ratio, spark timing and cylinder condition.

Automatic Transmission/Transaxle Test Prep: Torque Converter Basics

The concept of using a torque converter, oil pump, planetary gear sets, clutches, bands and a computer-controlled hydraulic valve body to transmit torque and to change gear ratios is relatively simple. To illustrate, the torque converter allows the engine to idle in gear with the vehicle stopped and multiplies engine torque during the initial stages of acceleration.

Diagnosing Inoperative Fuel Pumps

As I’ve discovered recently, times change and so do the procedures for diagnosing inoperative fuel pumps. Just a few weeks ago, I diagnosed a case in which the owner had started his vehicle for several months by spraying starting fluid (ether) into his truck’s air intake before he cranked the engine.

Reading Tire Wear Patterns

Modern tire construction has generally trended toward low aspect ratio tire casings with more flexible sidewalls and rigid treads. Although this type of construction has made tires less sensitive to negative camber angles used in many current steering geometry designs, many types of tire wear patterns continue to indicate problems in a vehicle’s steering geometry.

Diagnosing And Repairing Worn Brake Hydraulics

During a service writer’s efforts to sell competitive brake services at the service desk, he or she often focuses on selling “good, better or best” brake friction replacements, while ignoring the added expense of repairing brake hydraulics. Unfortunately, neglected brake hydraulic systems can cause an expensive warranty comeback or, even worse, a serious traffic accident. In any case, it’s important to advise a potential customer of the importance of servicing and repairing worn brake hydraulics.

Tech Feature: Ignition Coil Diagnostics

Import Specialist Gary Goms says there are a variety of opinions about how to test ignition coils and ignition systems. The most basic method is measuring a coil’s primary and secondary resistance. If a coil doesn’t meet the manufacturer’s specifications, it should be considered defective. But meeting primary and secondary resistance specifications on the bench is no guarantee that the coil will perform correctly under extreme heat and load.