Diagnosing Engine Problems

What's Wrong With My Engine?


It's a good idea to know how your car behaves when it's healthy, because if something starts to change, you'll know there's a problem. Your engine exhibits certain symptoms depending on the problem. A trained mechanic has many diagnostic tools at his disposal to pinpoint the noise you're hearing, but here are some common worries:If you're getting bad fuel mileage and your engine is missing a beat, there's probably a dead cylinder. You'll need to find the problem cylinder to find out why it's not firing.Are your spark plugs sparking? Are the tips covered in gunk? While disconnecting spark plug wires, be sure the engine is turned off to minimize risk of shocking.If you have sparks and your tips are clean, you may have a dead fuel injector.An oil test can help determine the problem. A sample of oil sent to a lab can reveal traces of metals in your oil. Aluminum in oil comes from pistons. Bearings and radiators are made of brass or lead. Steel comes from the crankshaft. If the test shows coolant or water, you know there's a leak.A badly tuned engine will use more fuel and money. Pay attention to when your dashboard engine lights come on and what you're doing. For instance, does your "check engine" light come on when you're going uphill, or at certain speeds?