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Car Talk: Cause should be found when a new battery dies

Dear Tom and Ray: I live near the ocean, and my less-than-a-year-old battery died this week. My neighbor, who jumped the battery with his cables, said that my connections should be disconnected and cleaned with a wire brush due to corrosion. My other neighbor said that she poured a can of Coke on her battery and it cleaned off all of the corrosion. Before I start pouring Coke on my car battery, may I have your opinion on her fantastic remedy? – Martha

Ray: We prefer Dr. Pepper, Martha.

Tom: If you do have a lot of corrosion between the posts and the terminal ends of the battery, it can prevent the battery from being charged completely, or discharged when you need the power.

Ray: But you shouldn’t have that kind of corrosion on a year-old battery – even if your next-door neighbors are Mr. and Mrs. Sea Cucumber.

Tom: Corrosion like that usually is caused by “out-gassing,” which means the acid in your battery is escaping from its container in gaseous form.

Ray: That can be caused by either a faulty battery – in which case yours should be covered by warranty – or a charging system that’s “overcharging” the battery and causing it to emit gas.

Tom: So you’ll want to take your car to a good mechanic, and ask him to test your battery and charging system.

Ray: If all’s well, the corrosion may be a red herring. Especially since we know herring live near you in the ocean. Your battery may have died due to human error: You may have left a dome light on, or simply left the car sitting for a few weeks without driving it.

Tom: If there IS a problem with the charging system, then you need to fix that before you blow through any more good batteries.

Ray: And Coke – with its carbonic and phosphoric acids – will help remove corrosion from battery terminals, as will any carbonated beverage (they all contain carbonic acid).

Tom: Or even better, and cheaper, mix a little baking soda with water to make a runny paste. Remove the battery’s terminal ends, smear your mixture on the battery posts and terminals, give them each a little scrub with a wire brush, and rinse it all off with a garden hose.

Dear Tom and Ray: I’ve always done the “bounce test” to check my shocks. I also go by the feel of the ride. My ’99 Taurus seems solid and rides great, but I’ve noticed that the rear end seems to be “squatting.” The front has about 3 inches between the tire and fender, but the rear end is about 3/4 inch! The trunk and back seat are empty. Seems like it would bounce if the shocks were bad, but it comes up and stops immediately. Is there something else I need to check? If the shocks are fine, along with everything else, is there a way to raise the ride height in the rear? It looks horrible! Is this unsafe? – Robert

Tom: It’s moderately unsafe, and probably hugely uncomfortable.

Ray: You’re confusing the job the shocks do with the jobs the springs do. Bad shocks will affect your ride and handling, but they won’t change the ride height of the car.

Tom: So it sounds like you have worn-out springs in the back.

Ray: The springs are there to absorb bumps; that is, to allow the tires to bounce up without making the entire passenger compartment bounce up with them.

Tom: The shocks are there to damp those vibrations and keep the tires from continuing to bounce up and down for five minutes after you hit a bump.

Ray: Shocks wear out over time due to how much damping they have to do, whereas springs wear out from carrying a lot of weight over time.

Tom: So perhaps you’ve schlepped a lot of heavy cargo in the trunk throughout the years. Or driven around with a couple of mothers-in-law in the back seat on a regular basis? That kind of weight compresses the springs, and eventually they just stop bouncing back because there’s no “spring” in them anymore.

Ray: Springs can also break. So it’s possible that you have a couple of broken springs in the back from one particularly overloaded journey (when you moved in 2006 and decided to carry your iron-ore boulder collection yourself to make sure it arrived safely). But since the height is the same on both sides of the same end of the car, it’s more likely that they’ve both just worn out and need to be replaced. Look into it, Robert.