Buying any car can be a stressful experience, whether the car is used or new. With new cars, though, the experience can become even more stressful if after the purchase has been completed you find that the car has major mechanical problems that will cost hundreds or even thousands of dollars to repair. By looking for some classics signs that indicate a car has mechanical difficulties, you help guard against a high repair bill soon after your car shopping experience.

The seller gets nervous when you start turning on the different components in the car. You should test everything about a car out before you buy, since after the transaction is over you have less recourse if something on the car doesn’t work properly. This means you should turn on every option the car has, including opening the sunroof, activating any four-wheel-drive system, using the air conditioning and heater, turning on heated seats, testing out the emergency flashers and flipping on the headlights and fog lights. A seller who is nervous about you testing everything out is likely trying to cover up defective features on the car, sticking you with a potentially large repair bill later.

The car is seriously dirty. We’re not talking about a few little spots on the paint that normally occurs from a little driving, but rather the car looks like it hasn’t been washed in a few weeks. This tactic is used by some sellers when the car has paint or body damage, especially if the car is black or another dark color. Dirt, water spots or other debris on the paint can obscure the presence of dents, scratches or fading paint. Ask the seller to wash and wax the car before you make an offer, since that will show off any body damage in gleaming detail.

The car leaks fluids of any kind. Always check for leaking fluid on the underside of the car, including when you first see the car and after you take it for a test drive. After the car has sat in a spot for several minutes or more, move the car a few feet and check the ground where the car was parked for any spots of fluid. Leaking fluids can point to blown gaskets or other potentially expensive repairs.

The engine makes strange noises. Before you ever make an offer on a car, stand outside the car while the engine is running. Even better, open the hood and look at the engine compartment while the engine is running and listen to the engine run for a few moments. If you hear any rattling, squealing or other strange noises, this can be a sign that the car has major mechanical problems the seller is trying to cover up. Sometimes these noises are too faint to hear when you are inside the car, even with the windows down.

The car’s exhaust is strange colors. Look at the tailpipe while the car is still running, after you have driven it around for a few minutes and the engine temperature gauge is at the normal operating level. White exhaust on a car that has properly heated up can indicate that antifreeze is leaking into the cylinders, which normally is caused by a blown gasket or damage to the engine’s cylinder head. Black smoke normally indicates that the car is burning oil. Both problems are expensive to fix, potentially requiring extensive work to be done on the engine.

The dipstick or coolant overflow look funny. Black or chocolate-colored swirls in the car’s coolant overflow container indicates that oil is leaking into the cooling system. A milky or frothy substance on the car’s oil dipstick can mean that coolant is leaking out of the cooling system and into the engine. Both problems likely are from serious damage to the car’s engine, which can require expensive parts and long hours for a mechanic to fix.

The car bounces multiple times after you push down on it. Choose one corner of the car, and push down as hard as you can so the car’s suspension compresses. If the car bounces more than once after you let go, this indicates the suspension is wearing out and will need to be replaced in the not too distant future.