Check that engine condition!
Now for a deeper look into the power plant. It is important to make sure that the engine will be reliable and not leave you stranded on the side of some forgotten highway!
How well does she run?
Faulty spark plugs or improper timing can cause what is called "spark knock" and is caused when the fuel in the cylinders is ignited too early and/or spontaneously which causes high thermal and mechanical stress, and can severely damage the engine. Spark knock should be addressed immediately in order to improve the engine condition.
A louder “metal-on-metal” sound,
similar to the sound that hammering a piece of metal makes, will tell
you that the engine condition is not good and has severe internal
damage. This sound is often heard when a major internal piece of the
motor, like a piston rod, or crankshaft, is damaged or broken. Unless
you plan on rebuilding the entire engine, an engine that produces this
kind of noise should be avoided at all costs.
If the oil looks black or sludgy, this will tell you that the oil has not been changed in a while and needs to be drained and refilled before driving the vehicle. Lift the car and securely support it with jack stands and drain the oil.
You can hold a magnet in the stream of oil that is draining out, and then inspect the magnet for any metal particles that it grabbed out of the oil. If metal particles are present on the magnet, this will tell you that some steel part(s) inside the engine, like the piston ring(s) or crank/camshaft, are damaged.
Damage to major internal components is likely caused by lack of oil lubrication, or oil pressure, which might indicate a faulty oil pump. This will also need to be addressed ASAP.
If you can inspect the oil that has landed in your drain pan, be sure to look for traces of water/coolant. Traces of water/coolant will tell you that the head gasket(s) are likely blown.
If you see any copper glitter floating around in the oil, this will tell you that the engine bearings, such as rod bearings, or main bearings have been worn down and will need to be replaced, which is a major headache, and will require total disassembly of the engine.
Checking the oil as described above can
certainly give you a good idea of how sound the engine condition and
internal components of the engine are.
You can also look at the sticker on the top or the side of the battery to determine when the battery was purchased. If the battery is, lets say a 3-year battery, and the sticker says that the battery was manufactured or sold 4 years ago, then you can expect the battery will need to be replaced shortly.
If a large amount of debris can be seen in the coolant, or if the coolant just looks dirty, the coolant system should be thoroughly flushed and refilled to help assure good engine condition. Also check the radiator/heater hoses to see if they looked dry-rotted, cracked or leaking. Poor circulating, or dirty, coolant can cause the engine to overheat and can lead to total engine failure!
The level should be at the “Full-Hot” mark. If it is not at the appropriate level, transmission fluid will need to be added. Also notice how each gear engages. There should be no strange or clanking noises, and the shifts should engage smoothly for automatic and manual transmissions. Transmission repairs are very involved, thus expensive, and should only be performed by a trained transmission specialist.
A squishy brake pedal will tell you that water or air may be present in the brake lines and you will need to flush the brake system thoroughly to get rid of the contaminated, or air ridden fluid to assure your safety.
A lot of pedal play will indicate that the brake pads are worn and will need to be replaced. Another indication of worn pad is the familiar “squealing” sound that occurs when coming to a stop.