In the market for a used car? The craigslist ad says it’s in perfect mechanical condition, but how do you know it’s really safe to drive? David Tracy over at Jalopnik was kind enough to provide a breakdown on what to look for so your purchase doesn’t crap out on you on the way home.
Modern cars are full of complicated, high-tech safety equipment, but pretty much every car of any vintage has components whose failure can put people’s lives in serious danger. That includes the things I’m about to go over: tires, steering components, suspension components, vehicle structure and fluids. If you make sure those things are up to snuff, you can rest easy.
When creating this list, I wanted to provide images of worn-out components so you, dear reader, could easily identify safety issues and remedy them as quickly as possible. That left me with a dilemma: where was I going to find a bunch of failed, unsafe components to photograph?
Thankfully, my personal fleet of shitboxes turned out to be riddled with safety hazards, allowing me to obtain a slew of informative images without ever having to leave my driveway. I’ll get around to fixing all of them someday. (Maybe.)
“Never skimp on tires.” It’s an adage to live by, and that’s because a good set of rubber shoes can be the difference between spinning out on a banana peel Mario Kart-style or continuing on with your awesome road trip to Wallyworld. Don’t drive with bad tires.
Some things to look out for:
1. Check Tire Pressure
This is an obvious to most gearheads, but it’s truly shocking how many cars are on the road with too-low tires.
If your tires are excessively bulging at the bottom, chances are you need to fill them up with more air. Grab yourself a simple stick gauge for $1 at the gas station, or get a good one like this Currie Enterprises one we had in our gift guide. Check to see if the pressure matches the recommendation found on the driver’s side door jamb or in your owners manual.
It’s always good to visually inspect your tires for nails or anything that might have punched a pinhole. Over time, even a tiny hole will deplete the air from your tire, and once your tire is flat, your vehicle’s handling and braking performance will be severely compromised.
2. Check The Tread Depth
The image above shoes a tire that’s seen far too many miles and needs to be retired. When in doubt, try the penny rule. Turn a penny updside down and shove it into a tread groove.
If the grooves are deep enough to swallow Lincoln’s head, Bob’s your uncle. If you still see the top of Abe’s head, you’ve got less than 1/16th of an inch of tread, and you’ll want to replace those tires as soon as possible.
3. Check For Uneven Wear
Uneven wear can be the result of poor alignment, worn out suspension parts or improperly inflated tires. If the outer edges are wearing faster than the center, you probably have an alignment problem. If the center is wearing faster than the outer edges, your tire is overinflated.
The alignment of the wheel in the picture above was so bad, it wore all the way through the rubber, exposing the steel belt. Rotating your tires can prevent this kind of severe uneven wear, but once it’s worn down to the belt, you need change the tire as soon as possible.
4. Check For Sidewall Bubbles
Sidewall bubbles look like tumors on the side of your tires and they form after a hard impact like with a pothole or speed bump. According to Nexen, a tire manufacturer, these bubbles form when air leaks from the inner layer of the tire into the body of the tire via a hole in the inside tire liner. In some cases, the actual sidewall cords can be damaged.
If your car has a bubble like the one in the picture above, replace the tire immediately, as a blowout might be imminent.
5. Check For Cracking
One of the areas where tires start to fall apart is right there on the edge of the tread, as it transitions into sidewall. If your tire’s got lots of cracking along that ridge or anywhere else, replace it.
6. Figure Out How Old The Tire Is
Since 2000, tires have come with four-digit codes indicating the date of manufacture. The first two digits represent the week, and the second two digits represent the year. The tire in the image above was manufactured in the fifth week of 2010.
How old is too old? Well, that all depends on the conditions to which the tire is subjected. Is it being abused on a track? What’s the weather like? Does the tire see lots of sunlight? Is it properly inflated? All of these factors play into how long a tire can last.
But recommendations for when you should toss the old shoes range between six and ten years. Manufacturers like Nissan and Mercedes say six years and Continental and Michelin recommend 10 years, according to Edmunds.
Check Your Ball Joints
Ball joints are part of a car’s suspension. They’re usually pressed into a control arm or axle, and join that control arm/axle with a steering knuckle. When you turn your steering wheel, you turn the knuckle and thus turn your wheels.
A line between the upper and lower ball joints is what comprises that axis of wheel rotation. They’re the points about which the wheel turns when you crank the wheel left and right, and they also restrain the wheel from moving in directions it shouldn’t. This means that when you make a sharp turn, and your tire experiences lots of lateral load and wants to rotate and fall on its side, your ball joints prevent that from happening.
Google “ball joint failure” to see the kind of carnage a bad ball joint can cause. It’s not pretty, and can force the car to an abrupt halt as the tire flops flat onto the pavement. At highway speeds, this could be catastrophic and even deadly.
The failed ball joint in the picture above was taken off my Honda Accord. The car shuttered down the highway as the spherical bearing bounced around in the worn-down socket. A few more miles with that on the car and I could have ended up in a ditch.
I think the cause of that failure was a bubble in my sidewall, which threw off my tire balance and resulted in increased stress on my ball joints. That’s the thing about ball joints: an unbalanced tire or another suspension component that’s gone bad could cause the joint to fail prematurely. Fixing a problem early early could prevent you from having to spend your life savings at the parts store.
I’ve since replaced that ball joint with a good one:
And here’s a picture of a lower ball joint (below). Notice how the rubber is in good shape. Ball joints very often fail due to moisture and dirt invading the rubber boot, contaminating the lubricating grease inside.
I should make clear that ball joints can and do fail without the rubber boot showing any signs of cracking, but those failures tend to happen over a longer period of time, whereas a cracked boot can fail a balljoint very quickly.
It’s also worth mentioning that just because you’ve got a cracked rubber boot doesn’t mean the ball joint is bad. If no moisture and dirt have seeped in, you may be able to just replace the seal, but I recommend replacing the entire balljoint.
If you’re just visually inspecting the car for safety, look for cracks in rubber boots and shuttering at highway speeds. If you’ve got access to a simple floor jack and a broomstick, you can push the wheel upwards and check if a ball joint has gone bad by looking for lots of relative motion between the knuckle and the control arm or axle. Here’s a simple way to check ball joints, as explained by YouTuber ChrisFix:
Check Your Tie Rod Ends
A tie rod is what connects your steering rack to your steering knuckle. Its job is to communicate your steering rack’s linear motion by imparting a moment on the knuckle. This turns the wheel.
If a tie rod end—the part of the tie rod that connects with the knuckle—goes bad, the wheel will have a tendency to erratically rotate about the ball joints, even if the steering wheel is pointed straight. This can cause your vehicle to snake down the road instead of driving straight, and can yield uneven tire wear and dangerous shaking at highway speeds.
If tie rod ends wear down completely, your whole wheel could turn too far and bring your car to an unintended stop.
Like ball joints, tie rod ends are ball and socket joints similar to human hip joint. And like ball joints, tie rod ends often fail after the rubber boot has cracked and allowed moisture in. Check to make sure the rubber is in good shape and plump with grease like the one in the picture above.
A good rubber boot doesn’t always mean the tie rod end is okay, and a bad rubber boot doesn’t mean it has failed. So you can test your tie rod ends by listening for clunks when turning the steering wheel, or follow YouTuber RatchetsAnd Wrenches’s video above.
Checking a tie rod end for play is just like checking a ball joint for play, except instead of pushing the wheel up and down while looking for relative motion between the joint and knuckle, you want to move the tire side to side as if turning.
For inner tie rod ends, which sit closer to the steering rack, and aren’t visible because they’re covered by a rubber boot, you can put your hand on the tie rod near that dust cover and feel for vibrations or clunks as you turn the wheel.
Make Sure You’ve Got Cotter Pins
Cotter pins keep critical suspension nuts from backing off. They are threaded through a hole in a bolt and twisted. If the castle nut tries to back off, it will run into the cotter pin, which has a very high shear strength, and be unable to loosen further.
Inspecting to make sure all your cotter pins are in place is good reassurance that your nuts won’t back off and your suspension won’t come undone on the road.
More important than your car’s ability to go is its ability to stop. A few things to look out for when inspecting a car for safety are damaged brake lines or hoses, fluid leaks, brake pad wear or damaged rotors.
1. Check For Rusty Or Damaged Brake Lines
If you live in the salt belt, you need to keep an eye on your brake lines. Those run from your master cylinder under your hood to your front and rear brakes at each wheel. Pay particular attention to the brake line that runs to your rear brakes, as it tends to get covered in salty slush, and is often ignored by drivers since it’s so far out of sight.
One pin hole in that brake line, and your brakes are useless. Don’t mess around with brake lines: if they’re rusty, replace them.
2. Check For Old Brake Hoses
Brake hoses attach your hard lines to your calipers, which bolt onto your steering knuckles. In the case of a car with a solid axle, a hose might attach between the body-mounted hardline and a distribution block on the axle.
Since the knuckle/axle moves with your suspension, manufacturers use a rubber, flexible hose to accommodate suspension motion.
These rubber hoses can get old and crack, and a hole in them can render your brakes useless. Replace them if they’re starting to look rough.
3. Check For Brake Fluid Leaks
Rusty brake lines and bad brakes hoses can cause leaks, but there are plenty of places for brake fluid to ooze out of. If you’ve got drum brakes, check the back of your brake drums. Moisture there could indicate a leaky wheel cylinder.
Also check the back of your caliper, particularly around the bleeder valve (the thing with the rubber cap on it) and where the brake hose attaches. The master cylinder, which is under the hood, as well as the distribution block, should both be checked for leaks as well.
Also check brake junction blocks like the one below. This one sits on my rear axle and and has been leaking for a while at one of the fittings.
4. Check For Damaged Rotors
This is basic car stuff now, but for the uninitiated, brake rotors are the discs the brake pads clamp down on to make the car stop. Stopping is a good thing.
If you see surface rust on your rotor, don’t fret. Rotors rust very quickly, and usually that surface rust will brush right off with one application of the brakes.
But if you see obvious warping, deep rust or grooves in the rotor, or if you feel shuttering in the steering wheel when applying the brakes, get the rotors either replaced or resurfaced. Warped rotors can cause you to lose control while braking, and can result in rapid wearing of ball joints and tie rod ends.
5. Check For Brake Pad Wear
When brake pads are worn down, they usually make a noise—that’s how they were designed. But if the brake wear indicator wasn’t installed properly, you might not be given much forewarning of bad pads.
The good thing is that you can often see how much pad you’ve got left by looking through the spokes in your wheel. Just peek between the brake pad backing plate and the rotor, and check to see if there’s friction material left.
6. Check Park Brake Cable Adjustment
Increasingly fewer modern cars have actual, physical hand brakes, but if yours does, you need to make sure it works right. Your park brake cable is your last line of defense. It’s a metal cable between your hand and your rear brakes.
It doesn’t rely on fluid to get you to a stop, so if all else fails— ay, you spring leaks in your brake lines—the park brake could save you. Make sure it’s tight and test it on an incline every so often. It can be adjusted via a nut either under the car or near the lever itself.
Check Your Sway Bars
A car’s sway bar connects two wheels on the same axle. If one wheel lifts, the sway bar will try to lift the other wheel as well. If one wheel drops, the other wheel will be pushed down by the sway bar. Thus, a sway bar always wants the two wheels to be at the same position on the Z axis (up and down), and if wheels try to do otherwise, the sway bar will twist.
If you take a turn at high speed, your inside wheel will want to lift off the ground, but the outside wheel, which is being pushed down, will push the inside wheel against the pavement via the sway bar. Thus, the sway bar acts as a torsional spring that mitigates roll, hence why it’s also called an anti-roll bar.
Sway bars are connected to the knuckles via a sway bar link. I’ve broken one of those mid-corner, and let’s just say it gets really hairy. Especially if you’re doing avoidance maneuvers at high speeds, having no sway bar can cause your vehicle to turn the shiny side down.
Sometimes sway bars can actually shear, so make sure yours isn’t broken, and make sure the bushings and the end links are in good shape, as bad rubber bushings can impact the sway bar’s effectiveness.
Check Your Suspension Bushings
Bushings are rubber isolators found in automobile control arms, sway bars and leaf springs. They’re similar to bearings in that they allow for rotational motion, but their benefit is that they dampen shock loads to reduce noise, vibration and harshness.
The relative motion between the two parts occurs is facilitated by the straining of the rubber bushing. If the control arm rotates, for example, the rubber bushing twists to accommodate that motion. If the bushing rots or goes bad, not only will the shock loads be translated into the body of the car, but the control arm will be given a larger range of motion, making handling unpredictable. It’s not always easy to see if rubber bushings are disintegrated, so here’s an explainer on how to check for bad bushings:
Check Your Fuel Lines And Hoses
Another thing to check for is fuel leaks. Fuel lines enter fuel rails or carburetors in the engine bay, so make sure that there’s no leakage at that fitting. If there’s an inline fuel filter, check to see if there’s any moisture near those hose clamps.
Also check underneath the car, where there can be connectors between hard lines and rubber or plastic fuel lines. Those are often sources of leaks.
Check Your Vacuum Hoses
I’ve had a vacuum hose spring a leak before, and, unfortunately, that was the vacuum hose connecting my intake to my brake booster. That means I lost power brakes.
If that happens when you’re driving downhill, you might not be able to get the car to stop. Make sure they’re not cracked like the one below.
Check Your Serpentine Belt
That belt that connects your engine’s crankshaft to its accessories isn’t just there to give you ice cold AC—it’s also there to run your water pump to keep your engine cool, your alternator to provide electrical power and, on older cars, your power steering pump.
The serpentine belt snapping will cause your car to overheat and run out electricity to produce spark, but on a more dangerous front, it could kill off your power steering. And if you’re mid-turn and you lose power steering, you could lose control of the car.
Checking the serpentine belt is straightforward, though. Look to see if there are any visible cracks, particularly in areas where it makes tight loops. If your car squeals during startup, your belt could be stretched. If you can take your belt out and loop it without seeing any cracks, like in the picture below, the belt is probably fine.
Check Your Throttle Cable And Linkage
If you’ve got an older car, check your throttle linkage for broken parts or obstructions. In my case, I’ve got a broken plastic part on my kickdown cable that prevents my throttle from closing all the way. This could cause the car to “run away.” I’ll have to fix that soon.
Also, my air intake clamp is rotated in such a way that it could also cause my throttle to stick open. I’ll rotate it accordingly.
Check Your Car’s Structural Integrity
Good, healthy suspension components are no good if they’re bolted a compromised structure. Especially if you live in the rust belt, keep an eye on the metal around where your suspension bolts up.
If you’ve got leaf springs, make sure your leaf spring mounting points, U-Bolts and shackles are in good shape. There’s considerable load transferred through the spring, so making sure the point at which it bolts to the body isn’t compromised could prevent an accident.
Check For Exhaust Leaks
Exhaust leaks aren’t always easy to detect, and they can be very dangerous. One of the byproducts of combustion is carbon monoxide, which can be deadly in high concentrations. I keep a carbon monoxide detector in my old truck, and found that it has a severe leak, but you don’t have to do that to detect leakage.
The first thing to do is to look under the car for rust on the pipe or near the muffler or catalytic converter. Heat catalyzes rust, so exhaust components do tend to rust through rather quickly.
If there are no signs of holes in the exhaust system, there may still be a leak at a gasket. The way to search for a leak is to listen for a sound very similar to the sound of human flatulation.
As Eric The Car Guy suggests, a shop rag in the tailpipe can exacerbate the noise, making the noise easier to detect.
The way I test for an exhaust leak is via Sea Foam. I pour it straight through my throttle body, and watch the white smoke come out of my tailpipe. If there’s any white smoke coming from underneath, I have a hole in my exhaust pipe or at a flange. If there’s smoke coming from underhood, my exhaust manifold is probably leaking.
Check Your Steering Linkage
Steering linkages should also be checked for play. Have someone turn the wheel and look at the steering u-joints and make sure they’re tight.
Check Your Lug Nuts
Your lug nuts are what keep your wheel attached to your car. If those things loosen, your wheel could fall off, and that would be silly now, wouldn’t it?
You ever see those little arrows on the lugnuts of public buses? Those are loose wheel nut indicators. They provide a visual indication if a lugnut has loosened.
Unfortunately, you can’t put those on your car, so the only surefire way to check your lugnuts is with a wrench or tire iron. They need to be good and tight, so put a little bit of weight on that tire iron and snug those lugnuts down. Ideally, you’d check your torque spec (usually between 60 and 100 lb-ft for passenger cars), but good and tight (GNT) will do the job.
Check Shock Absorbers
It’s usually apparent when a shock absorber goes bad. You hit a bump and your car keeps bouncing up and down. The shock is meant to damp that motion and bring the car back under control. But shocks can leak, like mine in the picture above. Check the body of the shock for oil and moisture.
Hat Tip to David Tracy over at Jalopnik
Image: Courtesy of Ludacris