Vehicle Diagnosis

Diagnosing Your Vehicles Problems

Car trouble symptoms can indicate minor or major problems with your vehicle. This glossary of terms should help you identify your vehicle's symptoms and assist you when discussing your concerns with your Certified Service technician.

1. Brake System

2. Engine
3. Steering and Handling
4. Odors and Stains

Brake System


Brakes Fade
Stopping distance seems to increase, causing longer braking distance, similar to braking at high speeds.

Low Brake Pedal
Brake pedal must be pushed unusually far to engage brakes.

Brake Pedal Pulsation

Brake pedal fluctuates while brakes are applied.

Vehicle has a tendency to move right or left when brakes are applied; brakes engage suddenly when applying steady pressure to brake pedal.

Contact Information

St Johnsbury Buick GMC
500 Memorial Drive
St Johnsbury, VT 05819

Sales: (802) 748-1355
Commercial: (802) 535-2890
Service: (802) 748-2939

Service & Parts Hours
Monday: 7:30am-5pm
Tuesday: 7:30am-5pm
Wednesday: 7:30am-5pm
Thursday: 7:30am-5pm
Friday: 7:30am-5pm
Saturday: 7:30am-12pm
Sunday: Closed

Cuts Out
Temporary complete loss of power.  Engine quits at irregular intervals.  May occur repeatedly or intermittently, usually under heavy acceleration.


Mild to severe pings, usually worse under acceleration.  Sounds like popcorn popping.


Engine runs after ignition switch is turned off.  Runs unevenly and may make knocking noises.


Momentary lack of response as accelerator is pressed.  Can occur at any speed. Usually most severe when starting from complete stop.  May cause engine to stall.


Pulsation or jerking that changes with engine speed.  Exhaust has a steady spitting sound at idle or low speed.  Not normally felt above 30 mph.

Rough Idle

Engine runs unevenly at idle.  Car may also shake.


Engine delivers limited power under load or at high speed.  Won't accelerate as fast as normal.  Loses speed going up hills.  Vehicle has less speed than normal.


Little or no increase in speed when accelerator is pushed down.  Continuing to push pedal down will eventually give an increase in speed.


Engine stops running or dies out.  May occur at idle or while driving.


Vehicle speeds up and slows down with no change on accelerator pedal.  Can occur at any speed.

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Steering and Handling

Suspension moves to extreme end of travel and hits compression bumpers.  Fells like a heavy thud.

Excessive Play
Steering wheel must be turned unusually far before vehicle responds.

Hard Steering
Vehicle is difficult to steer, especially during parking situations or when first started.

Vehicle moves to one side when steering wheel is released.

Rapid side-to-side motion of both front wheels felt in steering wheel

Mushy or spongy ride; vehicle takes a long time to recover from bumps in the road.

Vehicle shakes

Vehicle meanders, requiring frequent steering adjustments to maintain direction.

Odors and Stains

Antifreeze or Coolant Leak
Sweet odor, usually accompanied by steam from under the hood.

Axle Leaks
Black stains with heavy, thick consistency.

Burning Oil
Thick, heavy odor, sometimes accompanied by smoke from under the hood or from the exhaust

Coolant Streaks
Yellow, green, pink or orange stains that are lighter and thinner than oil.

Crankcase, Oil, Power Steering
Fluid leaks. Brownish stains.

Electric Short
Acrid odor, like burned toast.

Continuous, heavy sulfur odor - like rotten eggs.

Overheated Brakes or Clutch
Burning rubber odor.

Hot metallic odor usually accompanied by antifreeze/coolant odor.

Transmission Oil Leaks
Reddish stains.

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