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  • Diagnose my car problem

    Above 45 mph, the car has a slight knocking noise, maybe a tapping sound. Clearly coming from the engine, instead of say, the wheels.

    Thoughts?

    BTW, I'm retarded about cars

  • #2
    Re: Diagnose my car problem

    does the knock vary with engine rpms or speed, like does it happen when your foot is off the oedal and you're coasting?
    what kind of car, engine, mileage?
    can you park the car and make the noise without the wheels moving?

    Comment


    • #3
      Re: Diagnose my car problem

      True story. My Toyota 4Runner with almost 300,000 miles developed a "knocking" noise (actually more like a ticking noise) a couple months ago. Thought for sure she was finally about to lay down on me since the noise sped up as the engine rpms went up. Took it to my mechanic to get his opinion and all in the world it was was a spark plug that had backed out about 3 turns. The compression coming out of the plug hole was the "ticking noise" I was hearing.

      Comment


      • #4
        Re: Diagnose my car problem

        Without further information(e.g. Gravy's questions), it is only a guess, but maybe a timing problem. Could be minor or a serious problem with the engine.

        1. More of a knock or just a pinging(heavy vs light)
        2. Engine
        3. Mileage
        4. Does the engine run normal otherwise(e.g. temp, acceleration, idle, etc.)
        5. Do you notice strange smell or smoke from exhaust
        6. Does the engine burn excessive oil
        7. Fuel
        8. What is the temperature where you're located, does outdoor temp affect knocking?

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        • #5
          Re: Diagnose my car problem

          Car is 2005 Toyota Matrix. 53000 miles. Knocking occurs whether or not the accelerator is pushed and any speed above 45.

          Absolutely no other symptoms. Weather is temperate (we live in DC).

          Comment


          • #6
            Re: Diagnose my car problem

            sounds like a wheel bearing to me

            Comment


            • #7
              Re: Diagnose my car problem

              [quote author=chemhawk link=topic=3217.msg36732#msg36732 date=1295213609]
              Above 45 mph, the car has a slight knocking noise, maybe a tapping sound. Clearly coming from the engine, instead of say, the wheels.

              Thoughts?

              BTW, I'm retarded about cars
              [/quote]

              Hold the phone...on TOS you posted that you don't have a car....

              Comment


              • #8
                Re: Diagnose my car problem

                [quote author=thedeerehunter link=topic=3217.msg36735#msg36735 date=1295216662]
                True story. My Toyota 4Runner with almost 300,000 miles developed a "knocking" noise (actually more like a ticking noise) a couple months ago. Thought for sure she was finally about to lay down on me since the noise sped up as the engine rpms went up. Took it to my mechanic to get his opinion and all in the world it was was a spark plug that had backed out about 3 turns. The compression coming out of the plug hole was the "ticking noise" I was hearing.
                [/quote]

                Congrats. I'm roughly have that now and have my sight set on 200k.

                Comment


                • #9
                  Re: Diagnose my car problem

                  On that information, I can think of 3 possibilities.
                  1. Timing is off. Not terribly likely since the knock would be audible at idle and at speed, and more pronounced under throttle.
                  2. Have water in the gas. Possible due to the time of year, and will not normally appear at idle, mostly under throttle. But yours appears at speed with neutral throttle.
                  3. The most likely problem is a drive train/transmission problem, maybe a thrown/worn bearing, since you only hear it at speed. Try putting it in neutral for a moment while at speed and see if the sound goes away.

                  Comment


                  • #10
                    Re: Diagnose my car problem

                    [quote author=Jayhawk1977 link=topic=3217.msg36762#msg36762 date=1295230036]
                    [quote author=chemhawk link=topic=3217.msg36732#msg36732 date=1295213609]
                    Above 45 mph, the car has a slight knocking noise, maybe a tapping sound. Clearly coming from the engine, instead of say, the wheels.

                    Thoughts?

                    BTW, I'm retarded about cars
                    [/quote]

                    Hold the phone...on TOS you posted that you don't have a car....
                    [/quote]

                    LOL. We live in DC and don't drive. We own a car, but I literally haven't driven a car in 6 months.

                    Comment


                    • #11
                      Re: Diagnose my car problem

                      I'd speculate also that it could be a drivetrain problem. I think if it was steering related, as opposed to drivetrain, you might feel the click in your hands on the steering wheel.

                      if it was me, I'd put the premium, expensive gas in it for a week or so and see if that has any effect. if so, then you know it's bad compression because you've been buying cheap gas and you suck at life.

                      long shot: dollar bet that it's bad smog pump/secondary air injector that simply clicks at 45mph because it's plastic and crappy.

                      Comment


                      • #12
                        Re: Diagnose my car problem

                        [quote author=Jayhawk1977 link=topic=3217.msg36763#msg36763 date=1295230125]
                        [quote author=thedeerehunter link=topic=3217.msg36735#msg36735 date=1295216662]
                        True story. My Toyota 4Runner with almost 300,000 miles developed a "knocking" noise (actually more like a ticking noise) a couple months ago. Thought for sure she was finally about to lay down on me since the noise sped up as the engine rpms went up. Took it to my mechanic to get his opinion and all in the world it was was a spark plug that had backed out about 3 turns. The compression coming out of the plug hole was the "ticking noise" I was hearing.
                        [/quote]

                        Congrats. I'm roughly have that now and have my sight set on 200k.
                        [/quote]

                        If maintained halfway decently 200K on 4Runners is nothing (possible exception being the later models with available V8). You can't kill the damn things.

                        Comment


                        • #13
                          Re: Diagnose my car problem

                          It very likely could be a gas issue since you have not driven it in 6 months.

                          Comment


                          • #14
                            Re: Diagnose my car problem

                            I'd check your tail light flange. When those get our of whack the muffler bearings can ping.

                            Comment


                            • #15
                              Re: Diagnose my car problem

                              Comment

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