cooling system

Importance of inspecting cooling system on a used car:

     Cooling system essentially cools the engine and it's malfunction will result in being stranded in the best case scenario and destroyed engine in a worst case scenario.

What to look for when checking cooling system?

     Caution: whatever you do, do no open cooling system when the engine is hot. This includes recovery tank, radiator or any hoses or anything else that might de-pressurize it. 

     Before test drive check the level by looking at the recovery tank and making sure the level is within range. Recovery tank is a transparent tank that has black hoses connected to it and usually says something like "LOW COLD, MAX COLD, MAX HOT" on the side with lines that reflect the level of the coolant.

     Inspect all hoses that lead to and from the radiator and recovery tank and make sure they are snug and there aren't any traces or smell of coolant (coolant smells like rotten eggs and the fluid is usually green, blue or yellow in color).

     After taking the car out for a test drive look at the temperature gauge and make sure the car reaches operating temperature promptly and stays there for the duration of the test drive.

     After test drive, open the hood and try to spot any rotten egg smell. If you smell it, that means there is an active leak somewhere and it's better to avoid such car. While the car is running look at the exhaust and make sure no blue or rotten egg smelling smoke coming out of the tailpipe, as this indicate serious engine damage.

     Leave the car running for some time and check the gauge again and make sure the temperature stays at normal range. After about 5 minutes or so (depending on the temperature outside) the fan should turn on to dissipate the heat from the radiator. If it's not hot outside, it might not turn on for quite some time.

     Look at the recovery tank and see that the level is. It should go up a little from when the car is cold, due to coolant expansion. It definitely shouldn't go down.

Conclusion:

     Check the coolant level visually by looking at the recovery tank when the car is cold and hot. Do not open the cooling system at any point when the car is hot. Try to spot any rotten egg smell in the engine bay, as this indicates leaks. Make sure the temperature gauge stays in normal position throughout the test drive.