Marinucci: Embrace visual inspections of problem vehicles

Savvy service personnel know that a careful visual inspection is a vital diagnostic process instead of a tedious inconvenience.

Years of practical shop work have confirmed that good eyes and old-fashioned patience may reveal more about a problem vehicle than all the diagnostic gear in your service department.

However, tire dealers and service shop operators must set the tone — live the example — in order to convince workers to embrace the "look-see" on every vehicle.

This is particularly true on those headache jobs that seem to stymie a conscientious worker's best efforts to diagnose a customer's problem accurately.

Furthermore, experience suggests that the more often service personnel practice patient visual inspections, the more readily they'll recognize the clues they need to identify the vehicle's problem(s).

Countless times, I have found that the clue that saves the day is the one that shows me where human hands last touched that headache vehicle. The reason is that — sadly — the last person who worked on it bungled a repair and perhaps harmed something you wouldn't otherwise expect to be damaged.

Here, I'll cite several relatively basic diagnostic clues. Maybe these examples will spur you and your crew to look closer at details on problem vehicles.

The photo to the left is a worn tire — nothing tricky. It's just a reminder to inspect each tire prior to suspension work or a wheel alignment.

Logically, tire-wear patterns should correlate to wheel aligner measurements and vice-versa.

Suppose a vehicle has tire-wear issues and/or handling problems. Careless technicians may overlook, for instance, the fact that obvious tire-wear patterns don't agree with the toe or camber measurements on the wheel aligner.

Or, perhaps the tires have no wear patterns whatsoever but the aligner values indicate misalignment of some kind.

Tires that don't jibe with aligner values are a giant clue that something is not as it seems. Perhaps a tech mishandled or damaged the equipment; maybe the wheel aligner is out of calibration.

Sometimes the car owner has not given a complete vehicle history — or service personnel failed to gather that history. Never assume that the motorist understands what constitutes meaningful vehicle history. Instead, ask the right questions.

Remember that problems such as bent, broken or worn parts may cause tire wear by altering normal wheel alignment values. Not only are these abnormal values measurable, but they also commonly cause telltale wear patterns on the tires.

Another example involves a harmonic balancer from a popular Ford V6 engine. The toothed or serrated ring surrounding the forward part of the component usually is known as a reluctor, tone ring or trigger wheel.

The harmonic balancer slides onto the snout of the engine's crankshaft. As the crankshaft rotates, the harmonic balancer's reluctor teeth trigger operation of a vital sensor called the crankshaft position sensor.

The crankshaft position sensor's signal is one of the most important ones within the entire engine management system.

Bent, broken or distorted reluctor teeth cause an erroneous, unreliable crankshaft sensor signal. Then this inaccurate sensor signal wreaks havoc on the engine control computer's decision-making process.

In this particular situation, a Ford SUV's engine had failed. A service shop's manager quoted several repair options — including a used engine. The motorist chose the used-engine option.

A wholesaler who specialized in low-mileage engines shipped an engine to this shop; the engine had been strapped onto a wooden pallet.

The harmonic balancer shown to the right came from this used engine. Two of the reluctor teeth – located at approximately the 11:00 o'clock position — were damaged. The teeth had been bent inward, away from the crankshaft position sensor.

Interestingly enough, some gouge marks appear on the large diameter of the harmonic balancer at about the same clock position!

Our best guess is that someone jockeyed this used engine onto the shipping pallet with crow bars or pry bars. During this maneuver, the person thrust the bar where it didn't belong, damaging the harmonic balancer.

Here, the engine started but ran very roughly and the SUV's engine computer set a fault code for the crankshaft position sensor.

A diagnosis eluded the tech who had installed the engine. Eventually, the boss involved the shop's lead tech in the job. Fortunately, his visual inspection revealed the damaged reluctor teeth.

Replacing the harmonic balancer solved the problem.

Of course, selling a used engine can be a gamble.

Whether the engine is new or used, prudent techs always visually inspect that engine upon delivery. Sometimes, parts are damaged during shipping.

No one visually inspected this used engine for damage. The oversight cost the shop a lot of wasted time and created an angry customer.

Finally, the photo above shows both fresh electrical tape as well as OEM tape on a Toyota wiring harness. You see, I had to access some wires buried inside this harness.

Therefore, I cut and unwrapped some of the original tape. Later I wrapped fresh electrical tape around the harness.

Now, suppose that a vehicle has an electrical symptom — especially an intermittent issue. All things being equal, the sight of fresh electrical tape on a vehicle's wiring harness is a potential red flag.

New electrical tape suggests that someone opened up that harness for some reason and then closed it up again. This could indicate the last place human hands touched that vehicle.

Sometimes, a tech repairs a damaged wiring harness and wraps it with new electrical tape. But electrical symptoms appear later simply because the person did a shoddy wiring repair.

The presence of fresh electrical tape may be the clue that makes a tech suspicious of a particular wiring harness – especially if it carries wires related to the electrical symptom at hand.

In conclusion, your eyesight is a valuable diagnostic tool. Use it accordingly.