What is a solenoid?

Your vehicle’s starter motor has the important job of starting the engine. But something also has to start the starter. And that something is the solenoid. In most automotive applications today, the solenoid is attached to the starter, with the two of them getting removed as a unit when necessary.

How a solenoid works

When running properly, and as long as it has a supply of fuel, the internal combustion engine continues to run by itself in an ongoing process from the inertia of the engine’s moving parts. But starting the engine is a separate process to get that inertia moving in the first place. This is the job of the starting system, whose main components include the:

  • Battery
  • Starter motor
  • Solenoid
  • Starter switch

Starting an engine: The first action

The process involves not one, but two separate electric currents – a stronger one and a weaker one. When activated, usually by turning a key in the ignition switch, the weaker current passes through the switch and to the solenoid. At that point, the current forces two large contacts to come together in the solenoid, which allows the stronger electric current to pass through the solenoid’s contacts. These contacts carry a current that requires heavy wiring cables directly from the battery. This current is heavy enough that it would be unwise to send it through a hand-operated switching mechanism. Hence, the need for the weaker current through the ignition switch.

The stronger current passes to the starter motor where it initiates two separate actions. The starter motor is designed so that the electric current activates a lever, forcing a small gear outward on a spring shaft. When extended, this gear, called a pinion, comes in contact with a toothed gear on the outer rim of a large flywheel on the end of the engine’s drive shaft. This large gear is called the starter ring gear.

Starting an engine: The second action

The second action in a direct current electric motor is the rotation of its central shaft, caused by the larger current passing through the motor. A motor transforms electric energy into the mechanical energy of the central shaft’s rotation. It does this because the electric current interacts with the magnetic field in the starter motor and results in the rotor on the shaft beginning to turn. By the time this turning action reaches the motor’s designed top speed, the pinion at the end of this shaft has already engaged the ring gear on the flywheel. The engine then starts running on its own and the starter’s safety features automatically disengage the pinion from the ring gear. The spring brings the pinion safely back to its resting position and the job of the starting mechanism is done.

When starting, if you hold the ignition key in the “start” position a little too long, you will encounter a problem. Here, too, is a spring that brings the switch back to the “on” position from “start” as soon as you release the key. If you fail to do so, you will hear the evidence of your mistake pretty quickly. The good news is that your mistake is not as bad as it sounds. The safety mechanism in the starter has already released the pinion from the ring gear. The bad news is if you do this often or for any extended period, you may drastically shorten the life of the starter motor.


Summer Car Care Tips


For many drivers, the summer is the time of year when your tires hit the pavement most, and car care doesn’t take a vacation. Be sure your car is ready for all that mileage.

To help, here are some tips to get your car in tip-top shape for the busy driving season ahead:

• Wash and wax your car thoroughly. If you can afford it, have it professionally detailed. Direct sunlight can cause a car’s finish to become dull, but a thorough washing and waxing can also help keep your car’s paint and clear coat looking good.

It’s tempting to run the car through an automated car wash, but those big revolving brushes can dull the finish over time. If you’re not allowed to wash your car at home due to regional laws or neighborhood rules, seek out a good drive-thru wash and hand wax instead.

• Check and set your car’s tire pressure to the level specified in your owner’s manual or on the driver’s door sill. As temperatures warm up, the air in your tires can expand and that might impact the way the car handles.

Be sure not to over-inflate the tires. While low tire pressure can cause the tire to heat up if it’s not rolling down the road properly, extreme over inflation can cause a blowout in high temperatures. If you’re not comfortable doing this yourself, take your car to a shop like Big-O Tires, Sears Auto Center or Firestone Auto Care Center. Those kinds of chains will usually do it for free.

• Have a qualified mechanic do a visual inspection under the hood. If you’re comfortable doing this yourself, check for worn belts or hoses and make sure your coolant (sometimes called anti-freeze) isn’t too old. Coolant lasts a long time, but keeping track of when it was last changed, especially in older cars, can help you avoid overheating as the temperatures gradually climb.

Tips for Car-Sick Children


Packing up the kids for a road trip can be difficult. Making sure they are stocked with things to do to keep them occupied can be a tough battle on its own. If car sickness is thrown into the equation, road trips can be even more of a struggle.

“Car sickness occurs when the brain receives mismatching information from the ears, eyes and nerves in the extremities,” said Jodi Breska, a family physician at Mayo Clinic Health System. “The results of this sensation are upset stomach, fatigue and, of course, vomiting.”

Breska said this experience is fairly common for children ages 2 to 12.

Although the reasons children are so prone to car sickness are still unexplained, Breska offers some suggestions that might help you keep your child from getting car sick on your next trip:

– Cut down on sensory input. Loading up your kids with movies and books during a road trip might not be the best thing for them, especially if they are easily car sick. Encourage them to focus on things outside the vehicle instead.

– Offer distractions. Tal­king, listening to music and singing songs with your child could serve as a good distraction during a car trip.

– Provide adequate air ventilation. Make sure the car is free of odors and there is a decent amount of ventilation.

– Be careful with snacks. Greasy and spicy foods are not going to be good for your child before a car trip. If the trip is going to be long, feed your child a small, bland snack before you leave.

– Try medication. If your child is 2 or older, ask your child’s health care provider about over-the-counter medications available for car sickness. Dimenhydrinate is available for children 2 and older, and diphenhydramine is available for children 6 and older. Drowsiness is a common side effect of these drugs.

Driving tips to help reduce your summer fuel costs


Whether you are taking a trip this summer or just running errands around town, there are steps you can take to improve your fuel efficiency and save money on fuel in the summertime.

No matter the price of gas, maximizing your vehicle’s fuel economy just makes good sense for reducing global climate change and conserving a non-renewable resource, according to a recent segment of MotorWeek Television. Today’s vehicles are equipped with fuel-saving technologies, but there is plenty you can do to get the most miles per gallon from whatever you drive.

Chicago Area Clean Cities, a nonprofit coalition focused on promoting cleaner energy for commercial and municipal fleets in Chicago and the surrounding suburbs, offers these tips to help you improve fuel efficiency in the summer:

• Read your owner’s manual for detailed information on how your vehicle’s air-conditioning system works and how to use it efficiently.
• Park your vehicle in shady areas or use a sunshade to keep the interior from getting too hot.
• Do not use the AC more than needed or set the temperature lower than needed.
• If you are driving at high speeds, use the AC instead of rolling down the windows. If the vehicle is too hot, you may lower the car windows to release hot air for the first few minutes. Once the hot air has left the vehicle, switch to using the AC.
• Avoid excessive idling. Idling can use a quarter to half a gallon of fuel per hour, and even more if the AC is on. Do not idle the vehicle to cool it down before a trip; most AC systems actually cool the vehicle faster while driving.
• Use cruise control while driving on highways to maintain a consistent speed and conserve fuel.
• Remove any unnecessary weight from the vehicle. Vehicles with heavier loads tend to have reduced fuel economy. An additional 100 pounds in your vehicle can reduce fuel economy by one percent.
• Avoid transporting cargo on the rooftop of the vehicle. Traveling with cargo on the roof increases wind resistance and can significantly lower a vehicle’s fuel efficiency. Rear-mounted cargo has a much smaller effect on fuel economy than rooftop cargo.
• Avoid aggressive driving. Aggressive driving (speeding, quick acceleration and heavy braking) can reduce fuel economy by as much as 33 percent at highway speeds and 5 percent at city speeds.
• Ensure your tires are properly inflated. Tires that are not inflated to the proper pressure can reduce fuel economy by 0.3 percent for every one-pound per square inch (PSI) drop in pressure in all of the tires. Having your tires inflated to the proper pressure is also safer and can help tires last longer.
• Pay attention to the speed limit. Not only is this a safe practice, but also gas mileage tends to decrease when driving at speeds above 50 miles per hour.