MORE AT POPULAR MECHANICS
1. A slapping noise that increases tempo with vehicle speed
This is the sound of a tire dying. Its tread is separating from the carcass of the tire. As the tread leaves the tires, it may turn into a giant steel-reinforced Weed Eater. It can cause massive damage to the vehicle’s bodywork as it leaves the tire. So if you hear it, don’t keep driving.
2. The smell of pancake syrup
A sweet scent coming from the engine bay probably means the vehicle’s cooling system is having problems. The smell and (we’re told) sweet taste of most automotive antifreeze/coolant comes from its ethelyne glycol. The source of the leak could be anything from an old, cracked or ruptured radiator hose to a water pump on its last legs. Ignore this smell and you could wind up stranded miles from help with an overheated engine. If you find an green, orange, or yellow puddle under the car, the issue is beyond looking the other way.
3. Puddles in your parking place
A puddle under your car can mean anything from “it’s really humid today” to “you cross-threaded the oil-drain plug and I’m bleeding to death.” When you see fluid under your car, take note of its color and location under the car. Rub a bit between your fingers and smell it. Most often it’ll be water coming from the air-conditioning condenser. If it’s clear and oily, it’s probably power steering fuid, check for leaks around the pump or power steering rack. If it’s darker, slippery, and you’ve recently had your oil changed, it could be a puddle of clean oil resulting from the fact that the mechanic damaged the oil drain plug or improperly installed the oil filter.
4. Other kinds of puddles
Reddish-brown fluid and a lightly oily feel is your automatic transmission telling you that a line running to the trans cooler could have been punctured or the transmission has a seal going bad. If the ATF fluid also has a burnt smell, that transmission probably need an overhaul. If you find an oily fluid on the inside sidewall of a tire, that’s probably leaking brake fluid. Lost brake fluid means a likelihood of air in the brake lines and almost zero braking power, so get it checked out ASAP. If there’s a very dark, heavy, sticky oil under your truck’s rear axle, the seals in your differential could be letting go.
5. Squealing like a pig
A high-pitched whining or squealing that comes from the engine bay and matches engine speed is often an accessory belt in its death throes. Back in the day, we could limp to a service station with a broken water-pump belt or the separate alternator belt. Today’s belts turn myriad devices including power steering, water pump, air conditioning compressor, and alternator. A broken belt will likely leave the car DRT (dead right there).
If you’re greeted with a high-pitch squeal when you tap the brake lightly while at speed, what you’ve got is brake pads or shoes at the end of their life. The squeal comes from a tab of metal built into the pad that becomes exposed as material wears away. If the noise changes or goes away, head to the mechanic today.
6. Grinding noise 1
If you’ve continued ignoring the squealing brakes and they go silent, the next noise you’ll hear from them is a powerful grinding. The last of the pad has ground away and the metal backing plate is now clamping directly onto the brake disc. Braking effectiveness is greatly reduced and the car is now dangerous. Not only that, but your repair bill is going up, too, since the discs will have to be replaced as well.
7. Grinding noise 2
If you hear a grinding, clicking, or rumbling noise during a tight turn in the parking lot, it’s likely a failing constant-velocity joint on a front-wheel-drive car. A CV joint allows the front wheels to both receive power and turn. Ignore this long enough and you’ll have a one-wheel-drive car at best, and likely a paperweight car unless it’s fitted with a limited slip differential.
Other grinding noises could also be anything from a pebble lodged between the brake pad and the rotor to a failing alternator to bearings going dead. Grinding noises are always bad—ignore them at the expense of your pocketbook.
