Most used SUV listings lead with glossy photos and a low price, but the details that decide whether you're buying a reliable vehicle or a money pit are never in the ad.

Instead, they're hiding under the chassis, behind the wheels, and in the service records. Here's where to point your flashlight.

Start with the transmission fluid

Pull the transmission dipstick if the SUV has one and check the color. Fresh fluid is reddish and clear. Dark brown or black fluid with a burnt smell points to a transmission that's been running hot, and that's an expensive repair on any vehicle. On a sealed transmission with no dipstick, ask for service records showing a fluid change, and take a short test drive that includes a few firm acceleration runs to feel for slipping or delayed shifts.

Check the coolant and radiator

Open the radiator cap only when the engine is cold, and look for rust-colored sludge or oil streaks in the coolant. Oil in the coolant can mean a failing head gasket, and that's one of the few repairs that can total an older SUV. Look at the radiator itself for green or white crust around the seams, and check the overflow tank for cracks. A 2010-era Toyota 4Runner with a clean cooling system is a very different purchase than one with a weeping radiator.

Inspect the suspension and bushings

Grab the top of each front tire and rock it back and forth. Any clunking or looseness points to worn tie rods or control arm bushings. Then look at the rubber boots on the CV axles, especially on all-wheel-drive models. A torn boot throws grease onto the wheel well, eventually destroying the joint. On a Honda CR-V, a split CV boot is a $200 fix if you catch it early and a $600 job once the axle starts clicking.

Look hard at the four-wheel-drive system

If the SUV has a transfer case or a low-range gear, test it. Engage four-wheel drive on a gravel lot and listen for grinding or hesitation. On a Jeep Grand Cherokee, a transfer case that won't shift cleanly is a sign of neglected service, and a rebuild can run past $1,500. Check the differential fluid too. Metal shavings on the drain plug magnet mean wear that's already happening.

Scan the frame for rust

This matters most if the SUV spent time in a snowy state where road salt is common. Crawl under the vehicle and tap the frame rails with the handle of a screwdriver. Solid metal rings; soft spots thud. Pay close attention to the area around the rear wheel arches and the body mounts. Frame rust is the one problem you can't fix with a wrench, and it's the reason some otherwise solid trucks get scrapped.

Run the engine cold and listen

Ask the seller not to warm the engine before you arrive. A cold start reveals timing chain rattle, lifter tick, and exhaust leaks that disappear once the metal expands. Let it idle for two minutes and listen near the front of the engine. On a Ford Explorer with the 4.0-liter V6, a timing chain rattle on cold start is a known weak point and a $1,000-plus repair.

Check the brakes and tires as a set

Measure the tire tread with a quarter. If the tread is near the wear indicators, budget for a new set, and price all four tires for the specific size on that SUV. Then look at the brake rotors for deep grooves or a lip on the outer edge. Uneven wear on one side often means a sticking caliper, which is cheap to fix but easy to miss in a quick walkaround.

None of this replaces a pre-purchase inspection from an independent mechanic, and $150 to $200 for a lift inspection is the best money you'll spend on a used SUV. But knowing what to look for yourself means you'll spot the obvious deal-breakers before you pay for someone else's opinion. Bring a flashlight, get the engine cold, and check the parts that are expensive to replace. Your future self will thank you.