When shopping for a used car you should make an appointment to view a car for sale and specifically request that they do not have the car started or warmed up until you get there. When you arrive you can pop the hood and feel the engine temperature by placing your hand on or near the block which is the main component of the bulk of the engine. This large piece of metal will retain heat for hours after warming up. If the engine is still warm consider coming back another time or moving on to the next prospective car.
Starting a car from a cold start is critical in helping to gauge the condition of the motor. Difficulties in starting, or weak cranking or funny noises are all indications of systems in the engine which are no longer running optimally. Still, before you even want to start the car you need to do a complete inspection of the fluids in the engine.
The first thing to check is the engine oil. To get an accurate level reading the car must be parked on a flat and level surface and it is best if the car has been parked overnight and not running. The oil that is on the dipstick when you remove it should be amber in color and mostly translucent. The darker and more gritty the oil the worse the vehicle has been maintained. The level of the oil is also important as this will tell you if the car is leaking or burning oil as well as tell you a little about the maintenance history of the car. Ideally the oil level should be to the full line indicator on the dipstick.
You should check for oil leaks by inspecting visually the underside of the engine. If there is an oil leak it will be very apparent in the caked on grease and road debris stuck to the underside of the car. If there is not you will need to watch for burning oil. If the oil level is low it has to be going somewhere.
Another fluid to check is the radiator fluid. For safety, the car must be completely cold before you attempt to open the radiator cap. The fluid in the radiator should be clean and clear despite usually being green. What you do not want to see is oil, debris or nothing. If you are comfortable working around cars and radiators you can start and run the car with the radiator cap off. If you have bubbles like a rolling boil when you rev up the engine then the car likely has internal failure in the form of lost compression in the engine escaping through the usually isolated cooling system.
There will likely be a brake fluid reservoir mounted to the firewall of the engine compartment. This would be the brake assist system and also may be utilized for hydraulic clutch assist in some vehicles. This fluid should be clear and mostly transparent. A leak in the braking master cylinder will manifest itself as a loss of brakes eventually but will start by visual fluid loss from the master cylinder.
All belts and pulleys should be in good physical condition free of cracking or worn edges. The wiring in the engine compartment should look clean and neat. Any signs of random wiring or messy wires is an indication that under-qualified hands have been working on the engine.
When you start the engine it should crank over, fire, and find a smooth and steady idle easily. Any hesitations, backfires or irregular idling are a sign of engine problems. Not all engine problems are serious and many can be simple such as a vacuum leak. Still it would be preferable to find a car with a great sounding and looking engine.
Smoke from the tailpipe will be burning oil, burning coolant or unburnt gasoline in some cases. Coolant burns white and smells like burning maple syrup. Oil burns blue/white/grey and can also be visible coming from the engine oil dipstick if you remove the dipstick while the engine is running. The term for this is “blow-by” which refers to engine oil blowing by piston rings which have become worn with age, heat and friction.
Finally the most important thing to avoid is an engine with a knocking sound. A knock is known to be the death march of an engine as it indicates a major internal engine component failure. Avoid knocking engines altogether.
Steven Goodale is the author of “Used Car Buying – A Mechanics Guide” which is available as a free ebook directly on the website http://www.UsedCarBuying.ca and includes step by step procedures for inspecting and purchasing used cars.