Q: My car has now reached 231,000 miles and is running fine so far. I'm liking it and not seeing any reason to replace it as long as it remains reliable. I have started to wonder sometimes when I'm running a little late for work if I'm being realistic about its reliability. Should I be worried? How much longer do you think I can go?
A: There are quite a few factors here to consider. If the car has received regular maintenance and hasn't suffered any serious boo-boos such as running out of oil or becoming overheated, the odds are decent for more trouble-free miles to come. Modern engines and transmissions can often make to 300,000 miles or more, with a few minor fixes along the way.
Here are things I'd consider to be the highest priority to inspect, replace or service in order to avoid a date with a tow truck: Your fuel pump is going to fail someday, and it will strand the car. Modern vehicles employ an electric fuel pump, typically mounted inside the gas tank. This gadget spins at about 3,000 revolutions per minute and can't be expected to last forever. Lifespan ranges from around 100,000 to 150,000 miles. If yours is still the original, or you aren't aware of when or if it's been renewed, proactive replacement may be worth considering.
Your cooling system is also a potential stranding issue. A ruptured hose or broken drive belt can also seriously damage the engine. If belts and hoses are more than five years old, I'd renew them, and have them inspected regularly. If your engine uses a timing belt to operate its camshaft, this should be renewed at the recommended interval, usually around 100,000 miles. A snapped or stripped timing belt will stop the engine and may cause serious internal damage. Chain-driven camshafts aren't likely to suddenly fail.
Your starter is also going to wear out. If your driving habits involve lots of starts and stops as opposed to longer freeway stints, it's likely on borrowed time. Batteries also don't last forever; perhaps 5 or 6 years. Slow cranking and dimming lights may signal the end is near.
There are many other parts that may wear or deteriorate at 200,000 miles or more, but the symptoms will typically appear gradually or give some warning. Fluid leaks, worn suspension and steering parts, water pump leakage, alternator failure, worn or pulsing brakes, and air conditioning blowing warm _ there are quite a few, but these won't leave you at the side of the road. Alternator failure _ a glowing red battery light _ will usually allow you 1-2 hours of driving before engine shutdown).
Sometimes an engine near this mileage may burn an exhaust valve, resulting in a rough-running condition. It could perhaps develop a leaking intake manifold or cylinder head gasket, with coolant leaking into bad places inside the engine. These can be a chore to fix, but they aren't the end of the world. A valve job or gasket replacement is far cheaper than a replacement engine. Since the bottom two-thirds of an engine is almost bulletproof, a top-end repair can make a lot of sense.
I wouldn't be concerned about your odometer reading at all. With some proactive checks and renewals, you may be good to go for another 70,000 miles or more.
Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, Calif. Readers may send him email at firstname.lastname@example.org; he cannot make personal replies.