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The Basics of your Vehicle's Mechanical Inspections




Mechanical inspections aren't as involved as they sound, at least not in this context. However, they are very necessary to avoid accidents and avoid staining your driving record. Remember an accident on your claims history or driving record could affect your potential auto insurance rates. At the very least, you will be a long way from getting very cheap car insurance without deposit plans and reduced coverage costs.

In terms of the monthly inspection, this part involves checking out soft, rubber items that see consistent wear or friction. In practical terms, that means the engine's belt or belts and the car's tires. While visual tire inspections should be an everyday thing, this is the time to set a few minutes aside to take a really good look at the tire's tread wear pattern – often the first and last warning you'll get when it comes to inflation pressures and suspension problems.

Engine's Belts

Modern cars typically use serpentine belt systems, so-called because they “snake” in and out of the engine's pulleys instead of wrapping around them like a V-belt. Serpentine belts are smooth on one side and ribbed on the other. In a sense, the ribbed side works like a series of tiny V-belts, using four to six tiny V's to grab grooves in the pulleys instead of one big one. But while this system is reliable and superior to the V-belt in most ways, it's just as much if not more prone to wear. When inspecting the belt, you'll need to focus on three key areas: excess tooth wear or cracking missing belt rib sections, worn or frayed edges, and belt deflection.

Testing belt deflection

Belt deflection is the simplest and most effective belt test and will tell you a lot about its length and condition.

Find the longest open span on your belt and press on it with one finger. The rule of thumb is a 1/2-inch deflection from the static position; any more than that and you're probably in need of a new belt. An extremely worn tensioner spring will also cause excessive belt deflection, but this is pretty unlikely to manifest with only a finger or two's worth of pressure on the span.

Examining belts

After checking the deflection, break out a flashlight and closely examine the belt itself. The smooth side should be smooth, even, and black, but not shiny. A shiny smooth side or one that clearly indicates the underlying crisscross pattern of the belt reinforcement fibers is on the verge of snapping in twain.

Look at the ribs on the underside of the belt

Check the peaks of the ribs. If they look shiny and polished, then the belt has worn down far enough that the peaks are hitting the pulleys. Cracks large enough to catch even slightly on a well-manicured fingernail will seriously compromise the rib's integrity. When the cracks get big enough, you'll lose chunks of the rib. If you see any chunks missing at all, or if the ribs feel jagged to the touch, then it's time to consider installing a more supple serpent.

Tire Tread Depth

You may have been checking your tires every day for signs of damage. However, there's no reason not to do it at 3,000 miles. But this time, you'll go a step beyond the standard visual inspection and check tread depth.

The Federal government mandates tire replacement when the tread grooves reach 2/32 inch in depth. But that's a truly worst-case scenario, since tires are, for all intents and purposes, completely slick at anything less than 4/32 inch. With 2/32 inch of tread, water on the road can get trapped under the tire, causing the rubber to leave the road. When this happens, you lose grip and slide.

The penny and quarter tricks

Washington and Lincoln are two of the world's best-known former heads of state, and their heads can still help to emancipate you – from hydroplaning. The penny and quarter tricks have been around almost as long as there have been pennies and quarters, and they're still relevant today. If you place a penny on-end in your tread grooves and the tire tread blocks come up to the top of Lincoln's head (Figure 6), then you have at least 2/32 inch of tread left. Perform the same test with a quarter, and you've got a more useful 4/32 inch of tread. Flip the penny over and orient it so that the Lincoln Memorial sits as Henry Bacon designed it. If your tread comes up to the base of the memorial's steps, you've got a safe 6/32 inch left.

Tire Pressure and Tread Wear

Like fluid level, tire pressure is something you really should check once a week. Passenger car tires, as a rule, are designed to work with 30 to 35 psi of air pressure. Running higher pressure will net you a somewhat better steering response and fuel economy, while lower pressure will give you a better grip for cornering, braking, and acceleration. You must consider that you need tire pressure that makes you avoid a collision.

Drive with the proper tire pressure

If you're in doubt as to the proper tire pressure, check the vehicle placard. It’s usually on the inside of the driver’s side door jamb, but it may be on the inside of the gas-fill door or glove box door. This tag carries most of your vehicle's vital specs, including gross weight, maximum towing weight, and tire inflation pressure.

Under no circumstances should you use the maximum inflation pressure listed on the side of the tire; not only will this prematurely wear the center of your tires, but inflating to the maximum-rated pressure leaves very little margin for error where heat-induced expansion is concerned, which can lead to a severe car accident. In the long run, careless action can lead to car accident claims and subsequent increases in your insurance rate, and rejections from cheap auto insurance providers.

If you're loading down the car with 500 pounds of kids and cargo, you might consider adding another 5 pounds of air pressure over your standard inflation pressure. This will keep the tires from deforming as much under load, avoiding losses in fuel economy and stability.

What Causes The Tread To Wear Unevenly?

In a perfect world, your tires would wear evenly from one side to the other until they shave down to a nice pair of slicks. But in the real world, a number of things can cause the tread to wear unevenly. Consistent over-inflation will wear the center of the tread.

Under-inflation will wear the edges prematurely, causing the tire tread to arch upward or “cup” in the middle. Edge wear on the outside edge only, indicates excessive camber, while wear that starts at one edge and crosses the centerline of the tire indicates an improper “toe” setting.