When I first bought my car almost 5 years ago, there was this hint of a "clicking" sound coming from the motor. At the time I knew nothing about cars, I figured it was just normal wear and tear over the years.

As time progressed, the sound became louder and embarassing, so I decided to try and figure it out. Here are the details that I know:

- The sound is clearest underneith - behind front tires.
- At coldstart, the engine sounds normal, no clicking.
- The noise begins softly at first after about a minute.
- It becomes louder as the car warms up.
- The noise is loudest at idle and disappears with throttle.
- The noise sometimes lightens around oil changing time.
- The noise becomes more pronounced after an oil change.
- It was recommended that I flush the oil and run 4.5 quarts of "Marvel Mystery Oil" at idle for 30m and then flush and refill with regular motor oil. During this 30m period of time, the sound never appeared. As soon as I flushed and refilled with motor oil, it came back.

Any thoughts on this would be most appreciated.

Thanks,

 

Pull the dipstick out.

Does it still do it?

 

The sound is unchanged with the dipstick removed.

 

how fast is the clicking? like when you rev it, does it speed it, then you can't hear it, or is it constant speed, and you rev it and it totally disappears?

what weight/brand of oil do you normally use?

 

The speed of the clicking seems to be directly related to the idle speed. When I apply throttle, the sound will increase as it fades away and is completely unnoticeable at about 1,800rpms or so.

I use Valvoline MaxLife 10W-30. Although I have tried 10W-40. No effect.

 

may sound crazy...but the first thing that poped into my head is it may be a bent valve...

 

Exhaust manifold leak, check all the bolts and the gaskets

 

Just for the fun of it, I will post a video clip later this evening or tomorrow and attempt to capture the noise and location.

As for the manifold leak, I will check the bolts.

 

Lol check your PCV valve. sounds funny but thats what mine does too and thats what it is. Replaced it and all but the new one still does it.

 

The PCV valve has been replaced a few times, as well as a few tuneup's have been done (plugs, wires, cap/rotor, oil/filter, air cleaner, fuel injector cleaner, coolant flush, transmission fluid/filter, etc) since the noise first made it's ugly appearance.

The noise seems to be coming from the lower end of the motor.

I appreciate the ideas, keep em' comming.

 

see i got a noise like that took almost sounds like a valve or something but doesnt come from that direction. I have that noise and the pcv.

 

Here are two links... One is a recording from the engine bay, the other is from the exhaust. You can hear the sound faintly in both. I plan to do some more recordings later once the motor has cooled and the sound is more pronounced.

http://www.resonantecho.com/engine.mp3

http://www.resonantecho.com/exhaust.mp3

 

pull the valve cover's and check out what the oil looks like under there. If its like mine unforantly the dumbass who owned the car before me didnt take car of it and the oil is in clumps blocking passages to the rockers. but still could be something else?

 

The first recording sounded like valvetrain noise (tap tap tap). Are the valves adjustable on a 3.1 and if so have you adjusted them? I couldn't hear anything on the second one.

 

OHH! Youve got the GM noise! Ive never personally heard a 2.8/3.1 that DIDN'T make that noise. Granted yours is one of the louder ones Ive heard, but every 60* Ive worked on has sounded like that.