I am considering purchasing a car with 140,000 miles on it. What should I be looking for as far as things that will cause a large problem in the future?
With that mileage, you should except that the timing belt or chain was already replaced as well as the water pump and A/C Compressor.
All of those things are usually changed at 100,000 miles, then again at 200,000 miles.
Make sure they were changed. Other than that you should not have many problems depending on the brand.
If it is a Honda/Acura or Subaru or Toyota/Scion/Lexus, then you should be fine for at least the next 150,000 miles.
Replace sparkplugs every 2 years. Replace air filter every 6,000 miles. Replace Sparkplug wires and sparkpluus and distributor cap and fuel filter if they have not been replaced already.
1st trans problems.
2nd Water pump/Timing belt problems.
3rd make sure it was properly maintained with oil/tuneups.
4th: Leaks and knocking in the engine.
TRANSMISSION! Very expensive to replace and is probably on its' last leg of the race, lol. I wouldn't even consider a car with that kind of high miles on it. For that, take your money and put a down payment on something a few years old with low miles and get something with a warranty so that if there is a major repair; you're covered.
with that many miles. any thing can start to happen. not a good choice. with that many miles.1=engine 2=timing chain 3=fuel pump. 4=transmission.5=suspension. and so on.