The Car Is A 2002 Cambiocorsa. Whenever The Car Is Driven A High Speeds, I Hear An Intermittent Humming Noise Coming From The Engine. . . And It Is Not The Road Surface. I Haven't Noticed A Loss Of Performance - - Car Still Accelerates Etc.
Is it a high pitched humming, low pitched humming, a squeal? Any apparent place in the car that it sounds like it's coming from, left, right, only above 3500 rpm? Give us as much as you can so we can all put our thinking caps on. Is it metal to metal?
It's a moderate noise that appears to be coming from the engine. It only come on (and off) above 95mph. Does not appear to be rpm sensitive -- but difficult to be sure. It sounds like the difference between when you switch from driving on asphalt to concrete i.e., change in road surface . . .(but without the change). This only happens at high speeds and I have not noticed a lost of power when this happens . . the car maintains equal delivery of power . . . through the on-off noise . . . it just keeps making that on-off humming noise and I don't know what it is . . . .
Sounds like it is speed dependent.... So the electric cooling fans on the radiator have baffles, at some point in time when the pressure is enough, those baffles will open and that will cause the fans to start spinning whether or not the car is hot enough to turn them on. That sound could be just like the difference between running on asphalt versus running on concrete... Listen while you are driving around town or in a slower speed situation for when the fans come on and see if it sounds the same...
Other than that there is nothing that I can think of that would cause that difference in sound...
You might have a loose fairing on the bottom of the car but that would usually rattle as well so I don't think that is it..
Thanks for the feedback.
I drove around, and I can't hear the noise at low speeds . . . Wondering if the engine gets hot enough . . .the gauge says yes, but no noise . . . fan or otherwise.
I thought exactly what you said about the fan. However, when I called the service tech and asked about my theory, I was told that if I drive the car at between 95 and 100 for any lenght of time, the fan wouldn't come on and off intermittant. Rather the fan would come on and stay on until I turned off the car.
Now that I thinking about it, I've never heard the fan engage at all. Has that been a routine concern for this car in the past. when does the fan usually engage and how long does it usually stay on? Maybe there is a short and that's what I'm hearing.
once the thermostat goes over 198 the fans should
come on... in regard to your previous post the
fans wont turn on at 95mph but the air pressure
alone at that speed will spin the fans and make
a whirring noise and speeds around 95 may be where
that happens depending on elevation, etc.
. . . how would that account for . . . coming on for 4-5 seconds . . . off for 3-4 seconds . . . on for 4-5 seconds . . . off for 4-5 seconds etc. untill under 95, then no noise but above 95 . . . intermittent noise returns.
. . . wondering if perhaps certain cylinders may be malfuctioning . . . had this problem with a Ducati motorcycle once. I.e., found out that all cylinders were not functioning properly notwithstanding that I was still getting pretty good performance. Since I didn't get he car new, I'm not sure that I'm getting optimal performance, even though the car is very fast.