Sounds like a diesel

[mellonc]

My car is making a secondary noise besides the typical engine and exhaust noise. it sounds just like a diesel engine sound - that low grunting noise with gentle cluck-cluck sounds when high compression ignites fuel vapors. Of course, we don't have a diesel. And it's not pinging noise - I know what that sounds like as it sounds more like small rocks inside of an empty Coke can - higher frequency. I checked the power steering and that checked out OK. I checked the accessory belt and that is fine. Timing belt should be OK as i only have about 50K miles. I even cleaned the throttle body - my car idles like a brand new car. It burns about 1/2 quart of oil in 6000 miles - normal. Not a drop of engine oil in my driveway.

when I really rev the car into high RPM like 5000, the whole front end buzzes including my dashboard. Not sure it is connected with this low clucking noise. I was even suspecting a hole in my exhaust system but that whole path is clean. I checked the air intake and replaced the air filter....... The funny thing is.......I can't hear it with the hood open. It is only observable once you are in the front seats. And it's on constantly, gets noisier if I rev the engine hard but generally just there in the background.

Any idea???
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