• 2018

Sensory Diagnostics

Using Your Senses to Make Sense of Vehicle Repairs.

While nothing replaces your scan tools or computer-aided diagnostic checks, your senses can lead you to the point of the problem prior to plugging in a scan tool. Not only that, it can make you look like an absolute genius in the eyes of your customer – a technician completely in tune with any vehicle’s hidden language.

Take a Sniff.

From French fry grease to spoiled eggs, you can teach your nose to know where to look for the root of common issues that bring vehicles into your shop. Then use your diagnostic tools to confirm the issue.

THE SMELL: Syrup
THE TIME: When the engine is warm (either running or just shut off).
THE CAUSE: Coolant
THE ROOT: The most common leak points are:

  • Radiator, radiator cap (especially when the odor is strong outside the car)
  • Heater hose
  • Failed intake manifold gasket or cylinder head
  • Bad heater core (especially if you smell it from the passenger compartment)

THE SMELL: Horridness
THE TIME: Especially after the vehicle sits after a long drive.
THE CAUSE: Sulfur
THE ROOT: Gear lube leaking from the manual transmission, transfer case or differential housing.

THE SMELL: Old musty gym locker
THE TIME: When you turn on the HVAC.
THE CAUSE: Mildew
THE ROOT: Condensed moisture inside the A/C evaporator.

THE SMELL: Spoiled eggs
THE TIME: When the engine is running.
THE CAUSE: Hydrogen sulfide
THE ROOT: Probably the exhaust. The smell might be indicative of a fuel-injection problem, but is more than likely a failed catalytic converter.

THE SMELL: Burnt newspaper
THE TIME: When driving, especially during shifting.
THE CAUSE: Burnt clutch facing
THE ROOT: The clutch plate burning off from clutch slips. Either the driver is riding the clutch or the clutch needs to be replaced.

THE SMELL: French fry grease
THE TIME: When the engine is hot.
THE CAUSE: Oil
THE ROOT: It could be a few things:

  • Oil leaking onto the hot exhaust manifold. Look for smoke to try to stem the leak.
  • A leaky crankshaft seal spraying oil. Look for the oil on the ground and trace the leak upward.

THE SMELL: Burnt fabric
THE TIME: When the brakes are getting used a lot or used hard.
THE CAUSE: Brake pads
THE ROOT: Likely this is a seized-up brake caliper piston. Or, if the vehicle has a parking brake, it may still be partially engaged.

Listen Up.

Sometimes, a good starting point is to keep quiet and allow the vehicle to do all the talking. When you listen closely, it will often tell you everything you need to know about what’s going on under hood or under body. Of course, your diagnostic equipment can confirm everything you’ve heard.

GROWLING AND WHINING: It’s likely the alternator’s accessory belt, serpentine belt or crankshaft pulley.
FAST, RHYTHMIC TICKING: Fast, sequential ticks mean that the vehicle needs a lifter adjustment.
BIRD CHIRPING: Check for a failing water pump or worn-out serpentine belt.
WOODPECKER: Look for bad ball joints.
BUBBLING OR GURGLING: Check for a leak in the cooling system or a blown head gasket.

While there’s an amusement factor in listening to customers trying to imitate the sound coming from the depth of their vehicle, there’s still a car to fix. This handy website can help you work with customers at the counter to identify the clucks and clangs that brought them to your door: http://mycarmakesnoise.com

In Living Color.

There’s nothing pretty about a leaking vehicle, but it’s a beautiful thing when you can coordinate the problem with the color of the spot on the pavement. Your senses of smell and touch can also come in handy when identifying a leak, but remember, nothing replaces your diagnostic tools and equipment.

CLEAR: Best-case scenario, it’s water. Other scenario, it’s power steering fluid.

AMBER: Gasoline (check for cracked or broken fuel line or stripped drain plug).

RED OR PINK: Transmission fluid (probably leaking through its pan, fluid lines or broken seals). Power steering fluid is also often red or pink, but it smells like burnt marshmallows.

BROWN: Oil (check pans, gaskets, seals, plugs).

YELLOW: New brake fl uid (it gets darker with age and smells fi shy).

GREEN, BLUE OR PURPLE: Washer fl uid (feels watery).

RAINBOW: Coolant colors come in a variety of shades including bright green, yellow, pink and orange. All feel slimy and smell sweet.

Feel it Out.

In addition to feeling for hot spots around the vehicle or for frays and breaks on belts, sometimes, a test drive and your scan tools can help provide the answer you need to get to the root of the problem.

VIBRATING OR SHAKING: There are a lot of things that can result in shakes and quakes and it’s smart to check them all. Start with checking the alignment, if wheels and tires are out of balance, or for loose lug nuts. If you don’t have luck there, the problem may be a failing suspension, warped brake rotors, engine timing issues or loose seat-mounting bolts.
LEANING OR PULLING: Check the wheels, tires, steering or suspension. The fix could be as easy as adjusting the tire pressure or as involved as replacing shocks, struts, a wheel
bearing or the steering linkage.
SPONGY BRAKING: The feeling of spongy brakes is probably the result of air in the brake lines or low or old brake fluid, all of which can likely be fixed with a brake fluid flush.
LOOSE TURNING: If the steering wheel feels loose, something’s probably “untied.” Most likely it’s the tie rods and tie rod ends.
TIGHT TURNING: If the wheel is tough to turn, it’s probably the power steering fluid, pump or belt.

It Just Makes Sense.

While you may be able to diagnose a vehicle using four of your five senses before your customer has a chance to say, “Do you smell that?”, it just makes sense to confirm what you believe you
know. Remember, a great technician uses all the tools available to make sure repairs are done correctly and with certainty.

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