Used Car Buying: 8 Ways To Shop Like A Pro
Second-hand car buying is a recipe. Equal parts glad-handing and hustling (for buyer and seller alike). Season with information and a dash of common sense – then serve with indifference to the other person. It's the shot you get before the lollipop, the homework before the play, popping the question before the date. Before swapping cash for keys, it's typical to "kick the tires" (and see what falls off) – but there are often overlooked clues to the condition of important parts.
This guide covers eight crucial clues to a car's condition – signs that someone's selling you their trouble (a couple aren't deal breakers but can help you haggle a seller's price too):
- Brake Fluid (condition and level)
- Brake Pads and Discs
- Radiator Fans
- Oil Filler Cap
- Accessory/"Serpentine" Belt
- Power Steering (fluid and pump)
- Air Conditioning
Most don't even need a screw turned, but you may have to hunch down for a couple (but they're worth it). However rare you think bargains are, they're rarer – and a car can cost more than what you pay to drive away. What you find can indicate responsible car-care, or trouble.
Like pulling the engine-oil dipstick, brake fluid's condition is a clue to how the system was cared for. Look for a small bottle with a cap (usually black or yellow), with the words "DOT 3/DOT 4 FLUID" written on it. That's the brake fluid reservoir.
The "DOT" designation is fluid-type – there's also "DOT 5", but most cars use DOT 3-or-4 (they're interchangeable, #4 just resists boiling better under hard use).
Always use what the cap suggests – DOT 5 is silicone based and doesn't play nice with certain anti-lock brake parts.
You'll want to check both the fluid level and condition.
Fresh/healthy fluid will usually be amber or "honey"-colored. Brake fluid shouldn't be dark, black, or "muddied".
Dark and dirty brake fluid can indicate —
- High-mileage or contaminated fluid. Brake fluid is "hydroscopic" – it sucks moisture from the air (which occurs over time, or sooner if the cap isn't secured tightly). When moisture gets into fluid, it lowers boiling resistance and can damage components from the inside. A plastic syringe (available in pharmacies or market medicine aisles) can pull samples out for a better look.
Checking the level sounds simple, but the reservoir's plastic isn't "see-through" when new – and turns less clear with age. Small L.E.D. flashlights help (found cheaply at auto-parts stores or Walmart).
Shine the light from the side of the reservoir (so it creates a contrast between the fluid and empty space, making the level easier to see).
Low fluid can indicate —
- A leak along the hydraulic lines of the brakes.
- Worn brake pads. When pads wear enough, fluid must travel deeper into the system to squeeze them and slow the car, lowering the level at the reservoir (this is normal as pads age, but use the cost of new pads to haggle a car's price down).
Wheels with decently-spaced spokes let you peer in to check pad-thickness.
If pads don't look excessively worn, the fluid may be escaping instead of hiding. Leaks could drip to the ground and leave an incriminating stain, but underbody-plastics on newer cars (or owners savvy enough to move the car) lessen that clue's reliability.
Have a professional check the issue, be prepared to pay-for or repair-it-yourself, and insist the seller discounts the costs — or consider walking away.
Brake Pads and Discs:
While checking out the brake fluid, peek at the condition of the pads and discs.
Luckily, clues here are easily visible on most cars and (barring obvious issues like "pulling" or "shaking" when braking) shouldn't dissuade you from buying – even help you pay less.
Check for pad thickness if you already haven't for the brake fluid's sake. Check how much "meat" (friction-material) remains between the disc and pad backplate.
If the car hasn't been driven (because this'll hurt if it has), run your finger from the disc's center to its outer edge. See if the disc has a lip at its edge big enough to catch your fingertip.
Visible lip on brake discs can indicate —
- Having to replace the discs next time you change the pads. Brake discs are "wear-items" like the pads. I mean, nothing lasts forever, but wear-items are understood to need replacing several times in a car's life.
Brake pads bite into the discs (the force is powerful enough to transfer material between the two). Save for exotic performance brakes, discs are made of iron – which outlasts pads (three or four pads per disc, but depends on car and driver).
Because they're iron, they'll oxidize a bit on their face when wet (and a lot on their rim) but that's normal. Pads and discs can be relatively inexpensive for all but big trucks and sports cars. Just don't tell the seller that (if they don't know already) and use it to your advantage.
Also referred to as "auxiliary fans" (for supplementing airflow the engine gets when moving) – the radiator fans are vital to keeping the engine cool in stop-and-go driving.
For cars with engine-temp. gauges, watching the needle when driving is a good start (insist on both highway and stop-and-go test driving).
Fans can run differently from model to model, but at least one fan should turn on when using the A/C (it's a good idea to study how fans operate on the car you're buying). If the engine temperature remains steady and the fans start and stop like they should (check under the hood), don't stop there! Listen to them working — checking for squeaks or rattles.
Squeaks and rattles can indicate —
- The bearings in the motors of the fans wearing. Excessive shaking as the fans spin mean they're far gone and should be replaced soon.
With the engine off and keys out of the ignition (because fingers are cool, but high-fives from fans are not) – go back under the hood. Give the fans a twirl with your hand, checking for "sticking" and play in the motion.
Again, this would be the time to either shop elsewhere or let the seller know and haggle for their cost (audible fans aren't days from dying, but plan to replace them soon).
Oil Filler Cap:
Optimistically, the importance of engine oil is pretty well known. Even persons who don't know how it works still respect changing it. People that go to check a car can pull the dipstick to see if the owner has kept the oil at a good level (at least) – and make sure nothing syrup-like comes out. Unscrewing the oil filler cap isn't a bad idea either.
The dipstick can also have this clue, but the state of build-up on the cap can be a serious clue to engine health. Look for a white or "milky" residue. This is serious stuff. This is coolant and oil mixing in the engine.
White/milky sludge can indicate —
- Cracked or blown head-gasket. The head-gasket is a seal between the bottom and top halves of an engine, its "block" and head(s)". Engines need pressurized cylinders to make power and can run poorly with a bad gasket (or not at all). Gaskets also keep oil and coolant passages isolated (which can mix when the gasket is damaged).
If the car has a coolant-reservior – typical on newer cars (makes filling and purging coolant easier), check for the muddiness of oil there. Mixing in both strongly suggests mixing throughout the entire engine (worst of worst-case-scenarios).
I've got to tell you: if you're checking a car, find this – and still consider buying, you better be looking at something near-impossible to find and important to you. Replacing the head gasket is hard (and expensive) work, D.I.Y. or at a shop.
Like the mega-buckled and bedazzled belts you wear, accessory-belts accessorize your engine – or rather run its accessories: the alternator, A/C compressor, power steering pump, etc.
Pop the hood and check the belts at the engine's front (its "side" if mounted laterally/transversely). The inside of the belt (where it meets the pulleys) is ribbed to grab them properly – look for cracking along this surface.
Cracks in a belt can indicate —
- It's not long for this world. Plenty of belts near their suggested-use mileage don't visibly crack. Once they show up, prepare to change the belt soon – as a snapped belt means trouble. Worn accessory-belts can be clues to worn timing-belts/chains too. They're often replaced together as one is removed to reach the other.
An engine with a broken timing-belt/chain leaves you stranded for sure (and possibly with thousands in repairs, depending on the engine-type).
Get on the ground to check certain suspension parts – this will be easiest on trucks and SUVs. Taking a knee might not be enough, I'm talking belly or back on the floor (you're not buying a showroom car, don't wear showroom clothes).
You'll have a better look at the axles (and their rubber boots) and bushings for parts like the lower-control arms. You're not trying to see the condition of everything, but the state of what you can see could be a clue about what you can't.
Check how dirty the inside of the wheels appear. Brake dust and street-soot are typical, but black-grime can mean something else
Dark, caked-on grime can indicate —
- Torn axle-boot at the wheel-side. Modern "CV-joint" axles have rubber boots to hold in the joint-grease. A torn boot lets grease out, typically onto the wheel's inside, where it gets friendly with road dirt.
Some axles are serviceable: the boots can be replaced so the whole axle needn't be. Some aftermarket units aren't. Replace a damaged O.E.M. axle with one of those means buying it again if just a boot tears.
Now check for visible bushings. Imagine you're a car (please, keep reading). If your hands and feet are tires and you were in a push-up position – the cartilage in your knees, elbows, hips, and shoulders are like the suspension bushings.
Now do push-ups for 100,000 miles (science hasn't invented a car that feels because that would be sick).
Lower-control arm bushings are typically easy to see (and relatively in the same place from car-to-car). They isolate the bolt that secures the control arm to the car's subframe. Check for creases and lines in them.
Lines and creases can indicate —
- Tears in the bushing. While supporting the car's weight, the bushing is compressed enough to squeeze tears together (bushings torn badly enough will likely be felt in poor handling).
- Check a suspicious bushing with a flathead screwdriver. Carefully check for splitting (but don't tear it yourself! – you'd have to push hard though).
Worn bushings aren't total deal-breakers, but heavily degraded ones can be clues to the condition of the whole suspension . Pair the look of the bushings with the condition of the shocks/struts for an idea of how the seller up-kept the car.
Look for sagging at any corners and check a suspicious side (with the seller's permission) by pushing on a sturdy spot (that doesn't flex, i.e. – thin fenders and hoods) to check for excessive give.
Easy Lou Ferrigno, you shouldn't be able to see more than a slight motion, not the car's impression of jello.
Seventies Cadillac squishiness can indicate —
- Badly worn or "blown" shocks/struts. The springs in your car bend and flex to forces of the car changing direction. The shocks and struts regulate that motion (so that everyone wasn't laughably bouncing around as they drove along).
Check for shock-oil where the shock compresses (the "seam" where one half enters the other as the car hunkers down). Oil leaking means the seals in the shaft have failed and the part is kaput.
Shocks/struts can be surprisingly affordable on some cars and "beat-you-over-the-head"-expensive on others. If you're still interested (and remember: price of parts and labor), let the seller know the jig is up – and its going to cost them if you're still taking the car.
Like brake fluid, power steering fluid is a clue to the condition of the whole system. Also like brakes, the fluid provides hydraulic pressure.
A pump increases pressure to help steer in high-effort situations, like when driving slow. A car without power steering can give you a firm handshake (and Popeye-like arms).
The reservoir for P.S.-fluid can be marked with lettering, but some use symbols instead. Volkswagen/Audi uses a green cap, with arrows in both directions and a single drop.
Some reservoirs have dipsticks, but dipping a clean paper towel will give you a color-sample too (secure the cap tightly).
If the level is below the reservoir marks, the steering system may be leaking. Power steering-repair is typically expensive. Proceed carefully if suspecting a leak, have it inspected, or walk away.
Fluid color can vary from car-to-car. Subaru fluid is red when new, Volkswagen/Audi's has a green-tint. It all turns "muddy" or "dark" after prolonged use though.
Dark and dirty P.S.-fluid can indicate —
- Overdue for changing. The fluid becomes dirtied over use, minimizing its effectiveness. P.S.-fluid also lubricates the system. Fresh fluid helps seals and moving-parts last longer.
If the fluid level and condition looks fair, work the steering from side-to-side and listen for any audible whirring. The power steering should work near-silently (at most, the engine RPMs should dip slightly as the pump uses engine-power).
Whirring, whining, and squeaking can indicate —
- A degrading steering pump. As it ages, the pump's impeller and seals wear (leaking fluid). Those sounds are either the pump running low on fluid – or a pump that needs replacing already.
Tracking the issue down and the seller discounting repair-costs are crucial. This can be expensive enough to shop elsewhere.
Checking the condition of an A/C system requires more know-how and special tools, but there are clues that can point to obvious problems.
Make sure the seller hasn't warmed the car up before your test drive. Checking a car from dead-cold can uncover gremlins that disappear (conveniently) when warm. In the A/C's case, you'd want to test how long the system takes to cool the cabin.
Slow-cooling (or not at all) can indicate —
- Low-freon levels. Freon gas is the substance in A/Cs that allows them to cool air. Maintaining sufficient freon levels and pressure are crucial to A/C performance – some systems may not even turn on if they don't indicate required levels.
In a pinch, store-bought "freon kits" (a can of freon with a hose for refilling the system and a gauge to measure) can help you check if freon is responsible for a lazy A/C. Systems must sometimes be "charged" periodically and then behave as they should. If levels drop soon after charging, it's likely a leak (requiring professional servicing = $$$).
Listen for the A/C compressor kicking on-and-off while driving. Older models have the compressor run as long as the A/C is on, while newer cars have interior temp.-sensors that run the compressor as needed.
The compressor can be observed best while coming to a stop. Engine RPMs should rise slightly with the compressor running.
No change in RPM when turning on the A/C can indicate —
- The compressor isn't engaging. Compressors are constantly connected to the engine by accessory belt, but aren't engaged until turning the A/C on. This electrifies a magnetic clutch on the compressor that engages the pulley and spins the compressor.
The problem can be the clutch or the compressor itself. Certain cars may link the A/C with other systems, like the aux./radiator fans. If the fans aren't working properly, the A/C won't turn on (appropriately, if your engine isn't getting cooled, neither will you). Issues like that are typically blown fuses, relays, or other electric components (study up on your car).
If the A/C cools quickly and stays cool during your drive (take your time to let issues show themselves), let the car idle a bit after parking – a minute should do. Check for puddling underneath after.
Puddling water can indicate —
- Depends on its location. Puddling by the radiator can mean the condenser is damaged (the radiator wouldn't leak clear-water). Condensers are exposed to road debris due to needing airflow like radiators. Replacing the condenser can mean replacing other A/C parts = $$$.
- Water dripping anywhere behind the engine is typically the A/C removing moisture from the cabin and evacuating it (humidity is the enemy of feeling cool). As the A/C cools the interior, evacuated moisture condenses on the system lines beneath the car – dripping into puddles of water on the ground.
Used car sellers can have us at disadvantages: they know their car(s) and what to try hiding. A shady car seller abhors an educated buyer. Arm yourselves with basic car knowledge to be on the defensive and take control of buying your next set of wheels.