Hi everyone, I have a strange unidentifiable noise coming from under the bonnet that only occurs when starting the engine early in the cooler mornings, does not happen when say it's in the middle of the day and warm outside. It's impossible to pinpoint where this non-directional sound is coming from, it must be reverberating off of the flat surfaces in the engine bay. It's a continuous linear sound with a harmonic tone and isn't an intake air leak because I had a mechanic shoot this fog into the intake, no leaks detected. Is this what a friction wheel (serpentine belt) or main water pump sounds like when going bad? I can't think of anything else it could be, I'm sure somebody knows what this harmonic tone could be. Anyone? Thanks, Systemlord. Skip to .25 seconds and you'll hear it. https://www.youtube.com/watch?v=T_RNSgkNvy4&feature=youtu.be
It sounds a little like you A/C running but not engaged if that makes sense. Please list some info about your car for others. Year, Model, Mileage ect. I have no idea but now I am dizzy.
Oh sorry, I have a 2007 MCS (just turn over to 54k miles) and haven't turned on the AC for a few months, you just gave me an idea Dave, next time I hear that noise I'm going to turn on my AC and see if it gets louder, quieter or nothing at all.
It sounds like ether a loose heat shield or exhaust. I have had exhaust parts make this kind of noise till they heat up. Once they heat up just a little the metal expands and it gets quiet. Or it could be a lose bracket. In the morning after the car has sat over night and it's still cool check to make sure every thing is tight. Make sure to get under the car and check the exhaust.
If it is the heatshield, there is some sort of recall on it. The dealership replaced mine late last year before my warranty run out. Might wanna check with your local dealership. Heatshield still sucks, and I noticed recently that the cowling above the turbo/heat shield has started to warp.
Well Dave you were right, the sound is coming from the area of all of the pulleys. I heard that same harmonic sound but the interesting part is it changed tone a bit with the AC on, so now we know that it's either the AC pulley, friction wheel, alternator or the water pump. So if it turns out to be the AC what's involved in fixing it to where the sound is gone completely? Is this something most extended warranties would cover? I have a full 6-year powertrain warranty that covers any defects such as the oil feed line. On another note what do you guys think of my spark plug colors? These plugs I bought from Way, I have 3k miles on them.