DEAR CAR TALK: Our 2007 Mazda CX-7 recently had its steering pump lock up and burn out the belt. The belt and pump were replaced, but a week later, the car is starting strangely. When we turn the key, there is a loud and fast clicking sound from the driver’s side under the hood, and the engine doesn’t even attempt to turn over. After a few tries (about 25 seconds’ worth sometimes), the starter will engage, turn over the engine, and the car starts right up. However, while we drive, various warning lights flicker on and off, like the traction-control system and air-bag lights. What is happening that causes the clicking sound? Is it the starter solenoid failing to actuate the starter motor? Or is it something in the electrical system, and my mechanic didn’t do a thorough enough check?
— Benjamin DEAR BENJAMIN: When you hear a rapid clicking noise, it’s usually because the starter motor isn’t getting enough current from the battery. You’re hearing the starter motor’s solenoid trying to engage but failing to.
So, it could be a failing battery; it could be a bad alternator that isn’t properly recharging the battery; or it could be something as simple as a bad connection at the battery. You need to take it back to these guys and have them do a complete test of your charging system. That would include testing the alternator output and load-testing the battery.
Could it be related to steering pump failure? It’s possible. If the belt got really chewed up, some debris could have gotten into the alternator and caused it to fail. But it also could be coincidence. If the battery is on the edge of failing, that could just be due to old age.
Or the whole thing could be explained by your mechanic’s failure to tighten the battery terminal. If he removed the negative terminal from the battery to disconnect the power before doing the repair, and then forgot to retighten it, that would explain everything.
A loose connection would explain why the starter can’t get enough juice sometimes, but then eventually starts right up. It would explain why lights on your dashboard are coming on and off — as you drive around, the terminal clamp jostles around as you go over bumps.
And best of all, it would cost nothing to fix. Unless you count the price of embarrassment that your mechanic will experience. So ask him to check that first, Benjamin.
DEAR CAR TALK: My 2017 Toyota Tacoma calls for 33 pounds of air in all four tires. Where I live, during certain times of the year, temperatures can range from a high in the 70s to a low in the 20s and back to a high in the 50s, all within two or three days. This makes tire pressure difficult to maintain. What are the safe high and low limits for tire pressure? I know if I go with 35 psi, I will have a hard ride and better gas mileage. If I go with 29 psi, I will have a softer ride and worse gas mileage. But for safety, when do I need to actually adjust it, in either direction?
— Gary DEAR GARY: It’s always better to go too high than too low with tire pressure (to a point).
As you say, tire pressure changes along with the outside temperature. For every change of 10 degrees in the outside temperature, tire pressure changes about 1 psi. So if you fill your tires to 33 psi when it’s 75 degrees out, and it drops to 25 degrees at night, your tires will be at 28 psi. That’s too low.
I’ve been told that most tire- pressure monitoring systems warn you when your tire pressure drops by about 10 percent. For you, 10 percent would be a little less than 30 psi.
Low tire pressure always is more dangerous than high tire pressure. When tires are deflated, more rubber touches the ground, the tires heat up and you’re in danger of a blowout. If you remember the Firestone/Ford Explorer fiasco, the aggravating factors that led to many of those flawed tires exploding were heat ( high road temperatures) and low tire pressure.
Higher pressure generally is not dangerous, as long as you stay well below the “maximum inflation pressure.” That number is listed on each sidewall, and is much higher than your “recommended tire pressure” of 33 psi, Gary.
So, in your case, I’d recommend that you put 35 or 36 psi in the tires and just leave it there. You won’t notice any difference in tire wear, handling or braking.
And even if the temperature drops 50 degrees, you’ll still have 30 psi or more, which should keep your “low pressure” warning light turned off.
And if the temperature goes in the other direction, no harm will be done. As you say, at worst you’ll end up with better fuel economy and a slightly firmer derriere massage while you drive around, Gary.