How to Diagnose Engine Noise

Spartan engineEven those with lots of experience in car repairs can be fooled by the meaning of engine noises. To make matters more confusing, sometimes minor or innocent-sounding sounds may signal a severe problem, while a loud, menacing thud might be fixed with a $20 part.

But, here’s something that’s for certain: you shouldn’t ignore car engine noise. Doing so could lead to a catastrophic situation where your engine needs to be replaced. Plus, disregarding engine sounds could threaten your safety–and result in a breakdown at the worst possible moment.

While you always have the option of taking your vehicle to a mechanic for a diagnostics test, you can often get a good idea of what’s troubling your engine by listening to it.

General guidelines about engine noise

See if the car engine noises you’re hearing match any of the following sounds. Then look at some common reasons for that sound, and begin your investigation there.

  • Whirring: Could mean a bad water pump, power steering pump or alternator, or low power steering fluid level.
  • Knocking: Could be an issue with the distributor cap, timing chain or spark plugs.
  • Pinging: Could indicate a problem with the crankshaft, timing gears or transmission mount.
  • Hissing: Could mean a problem with the cooling system, exhaust, catalytic converter or vacuum line.
  • Popping: Could be an issue with the ignition wires, air filter, distributor cap, ignition module or engine compression.
  • Grinding/screeching: Hearing these engine sounds when you turn the ignition could mean a starter issue. But, if these sounds occur when you apply the brakes, it likely indicates worn brake pads or rotors.

Again, don’t turn your back on car engine noise, and hope that it’ll just go away on its own. Chances are it won’t, and you’ll wind up with an even bigger problem.

What did we miss? What strange noises have you diagnosed in your engine? Tell us in the comments.


  1. John V. Brennan says:

    Good Day! I hope you’re enjoying a pleasant one. Finding out where the noise is coming from is also sometimes tricky. A noise that’s over “here” may just be coming from something over “there”, as the sound can travel through the various components of your engine and/or bounce off the walls in your engine compartment.

    I found a Great way to find My noises, is to use a very inexpensive, but extremely handy tool: The Mechanics Stethoscope. No Mechanical Doctor (MD) should be without one. I’ve been using one forever, and not just on Automobiles… lawn mowers & tractors, small gas engine equipment, washers & dryers, electric motors, alternators and more…

    …what’s that screechy noise? …is it the alternator? …the water pump? the tensioner? Trying to find the noise within a rapidly spinning bunch of pulleys and belts can be an eeny-meeney-miney-mo exercise in frustration, and you certainly don’t want to just go swapping out parts til you find the right culprit.
    No Seasoned Mechanic or Do-It-Yourselfer should be without a Mechanics Stethoscope draped around their neck, toolbox, or workbench.

    If you don’t have one, can’t get to the store, and you need one Now, an Alternative is to take a long screwdriver, poke it at the various spots you want to listen to, and put your ear to the handle. It’ll work just like the stethoscope and transmit the sound from where it comes from to your ear. You’ll know when you find the sound-maker after poking around a bit. The sound will be loudest at the source of the problem. It’s also a bit of Fun to poke around your engine with a stethoscope and listen to the various sounds it makes. It may help you to be a better diagnostician, and maybe have the need to use a Steth less often, as you learn the different Normal sounds an engine makes.

    What every you do, have Fun doing it!


  2. On an 06 ford expedition with a 5.4, how do you change the spark plugs, comfortably, without breaking one?

  3. where is the glow plug censor for ford ranger

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