Mary Nohr’s Car Care 101
From the Outside In
Knowing what’s going on outside your car is as important as knowing what’s going on under the hood
Article Mary Nohr with Bonnie Fancy
Images Richard Simonds, Gary Anderson, and Stephan McKeown
This article is the second of two based on the Ladies of Mercedes program at StarTech 2015 in Cincinnati, where Mary Nohr, professional Mercedes-Benz mechanic and co-owner/operator of Nohr’s Auto Haus service shop in Buellton, California, presented a women-only presentation about car care. This time, Nohr focuses on basic external aspects of Mercedes-Benz maintenance.
Fuel and fueling
Open the fuel-filler door for access to the gas cap, where you’ll find the octane-rating placard. Always try to use this octane when refueling the car. When fueling your car, make sure the engine is off. Static electricity and gasoline fumes are an explosive combination. If you have sheepskin seat covers, touch a metal part of the car before fueling to repel static electricity. And leave your cell phone in the car when you gas up; it can also be a source of static electricity. Make sure the gas cap clicks when you screw it on – an unsecured cap will activate the dashboard’s check-engine light.
Down under
Check under the car for leaks and pay attention to stains or puddles on the garage floor. Yellow-green fluid is coolant; pink or red is transmission or power steering fluid; and brown is engine oil. Clear fluid usually signifies air-conditioner condensation, normally released as the car cools down.
Tire pressure and condition
On the driver’s door pillar – and inside that fuel-filler door – the recommended pressure for your tires is listed. Reference these pressures when you inflate your tires, using the lower-range pressures with light vehicle loads. Check the pressure of each tire with your tire gauge while they’re cold, before you drive. Do not use the pressure rating inscribed on the tires as this is the maximum pressure recommended; this may not be correct for your car. If you’re at a service station, use your own tire-pressure gauge; service-station gauges aren’t often accurate.
If one tire consistently has a lower pressure compared with the others, it may have a leak. Have it checked at a tire repair facility. Ask your mechanic to verify the pressures in each tire – including the spare – and record the recommended pressures on your information card.
Mercedes-Benz cars built since 2007 have a tire-pressure monitoring system (TPMS) that will display a warning on the instrument cluster if one or more tires are out of the acceptable pressure range. However, you should rely on this system only in emergencies: Periodically perform a manual check of the tire pressures yourself.
Check tires for wear. There are wear-indicator bars across the tire at right angles to the tread. If the tread is worn according to that indicator, it’s time for new tires. If the tires are worn unevenly, get the alignment checked while you’re purchasing new tires. All tires need weights on the wheel rims to balance them; make sure your wheels are balanced.
Be prepared
Check your trunk regularly to ensure you have the equipment needed in case of an on-road emergency. Otherwise, keep the trunk as empty and neat as possible, especially when having the car serviced.
You should be equipped to deal with a flat tire or damaged wheel, though in most situations, it is safer and more sensible to call for roadside service. Nevertheless, you should have the means to replace or temporarily repair the tire and wheel. Depending on the year and model of your car, the equipment might be a full-size spare tire, a donut spare, an inflatable emergency spare with tire inflator. If run-flat tires are standard equipment with your car, be sure there’s an emergency repair and inflation kit.
If you do have a spare wheel and tire, make sure you’ve got the jack in the trunk, a lug wrench that fits the lug bolts on your car, and the proper lug bolts for your spare tire and wheel. Many spare wheels use a different sized lug bolt – usually shorter – than those on standard wheels. Ask your mechanic to check this to make sure you have the correct bolts in the trunk.
Check pressure on your inflated full-size or compact spare tire at the same time that you check the tires on your mounted wheels. Always inflate a spare slightly higher than the highest rating to allow for deflation over time. Note that a compact spare, designed for short distances, will have a different inflation pressure – higher than normal tire pressures: Be sure to check the owner’s manual. Reading the manual and inspecting equipment will help you know what to do should a mishap occur. If in doubt, have your mechanic or service adviser check the equipment and show you how to use it. The edge of a busy highway in bad weather is never the best place to figure all this out.
Also, you should have an emergency first-aid kit, jumper cables, a quart of oil, hand wipes, cotton work gloves, a flashlight and disposable protective gloves. If you’ll be driving in cold temperatures, warm clothing, a blanket, and even some emergency food supplies aren’t a bad idea. Don’t forget tire chains if it’s possible you’ll encounter snow.
In the driver’s seat
Inside the car, make sure the seat is adjusted for your height. Your back should be firmly against the seat back. You should be able to rest your wrists on top of the steering wheel with a slight bend at your elbows. Adjust the seat and steering wheel until this ideal is reached. The headrest should not make contact with your neck, but with the back of your head.
Read the manual and learn the meaning of each dash indicator light. Indicators vary by model and year.
Turn the key to run (position two), not the starting position. Check the indicators. Notice the difference between the battery light and radiator coolant light on older cars: They can be easily confused. If the check-engine light comes on, check the gas cap to make sure it’s tight. If it’s still on, listen to the engine. If it sounds okay, drive it to the mechanic. If it doesn’t sound smooth or doesn’t respond to the accelerator pedal, call for a tow.
Know where your hazard light switch is and review the switch location occasionally so you can find it quickly in case of an emergency.
Rather than just starting the engine and driving away, listen to your engine from the inside and, every week or so, outside the car. Learn how it should sound. When driving, turn the radio off once in a while and listen for unusual noises. If there’s anything out of the ordinary, have your mechanic investigate the noises.
Emergencies while underway
Modern cars use a single multi-rib belt on the engine that runs all ancillary components. If you lose your power steering while driving, this could mean a broken belt, without which you’ll also lose the water pump; the engine could overheat if you continue to drive.
If the check-engine, oil or coolant lights comes on and flash – or the coolant temperature gauge signals red – your engine is seriously overheating: You can cause serious damage if you continue to drive. Pull off the road and stop at the first opportunity. If this isn’t immediately possible, turn the heater on “high” to full to mitigate damage. Do not continue driving until the cause is found and remedied.
Open the hood to cool the engine more quickly. Do not touch anything. Especially – do not remove the radiator cap. Visually inspect the engine area to identify the problem – loose or ruptured radiator or heater hose, broken belt or displaced radiator cap, for example – then call for a tow.
Another emergency: If you hear the engine misfiring or experience a significant loss of power and the engine doesn’t respond to the accelerator pedal, pull off immediately and call for a tow.
If you have a flat tire due to slow loss of air pressure, you will know by the way your car rides. It will feel mushy and squirmy and you may feel a pull to one side in the steering wheel. Pull over and stop. If there’s a blowout, you’ll hear a loud explosive sound and the car will immediately pull to one side. Do not step on the brakes. Move to the side of the road and pull off as soon as you find a safe location.
If your run-flat seems low, make sure the tire is intact; replace it as soon as possible. Runflats are rated for only 19 driving miles with heavy loads or 50 miles with light loads after loss of air.
Keep in mind that you can drive a reasonable distance on a flat tire without serious damage to the car. It’s much better to find a safe place to wait for a tow than to try to save the tire. Once you’re in a safe place, call for a tow from your roadside service provider or a Mercedes-Benz dispatcher (that number should be in your glove compartment). Only if you are completely stranded with no telephone service should you ever try to replace a flat tire on the highway.
If you do replace the damaged wheel or flat tire with your emergency spare, note that most spares are only safe to be driven for short distances and should be replaced with the proper tire and wheel as soon as possible.
If you need to have your car transported to a service facility, here’s what you need to know: In newer cars, there’s a tool in the toolkit in or near the spare tire in the trunk with a loop on one end and threaded like a screw on the other. On the front and rear of most new cars, there’s a small square removable cover off to the side that covers a hole into which the tow hook is screwed. Remove the cover and screw it firmly in place. Now tow personnel can connect their winch to the hook to pull your vehicle onto the flatbed.
Never allow them to hook onto any suspension components under the car with a hook; always use the tow hook – front or back. Be sure to remove the hook, stow it back in the trunk and replace the cover once the car has reached its destination.
The most important point to emphasize is that you should check the car periodically, generally as frequently as you refill the fuel tank. Not only will this practice keep you safe on the road, but it will give you more confidence when driving and a better understanding of your car’s operation when you talk with your service advisor.