Roaming vibration

[Scotty]

What can cause a roaming vibration around the engine bay? I hear it on occasion but can’t figure out where or what it is. Had it before I put in it the electronic ignition so I know it’s not that. Engine runs strong and quiet.

So far there’s no single common factor. If I accelerate it will sometimes drop, sometimes pop up. It comes and goes at idle as well. I had an issue with the exhaust vibrating and reattached it to the bottom of the trunk floor with a rubber hanger.

Any ideas? I don’t think it’s the engine because I’d expect that to be constant. But if I’m wrong, please let me know.

Thanks!

 

[Beamin]

I had a water pump going bad that had similar symptoms. Didn’t happen all the time. No common cause that I could pinpoint. Discovered the cause by accident. Had the hood open and the engine was idling, and I just happened to be looking at the fan and noticed the blur of the blades wizzing by changed just a bit. Shut it down and discovered a lot of play in the pump shaft. Odd that it wasn’t an issue all the time, but once I changed the pump, the problem went away.

 

[RootesRooter]

Maybe a cracked harmonic balancer? Loose bellhousing/engine bolts? Worn or too-stiff motor mounts?

Is the actual noise a buzz? Light clatter? Deep clatter? Do you feel/hear it while behind the wheel or just when standing over the engine compartment?

I keep a length of heater hose around the garage to track down such odd noises.

 

[sunalp]

Check your front valance. It could be broken or cracked and make the noise at a certain
frequency. Had one that did that.

 

[todd reid]

when the noise is present, step on the gas - does the noise change with the change in engine speed? If you are rolling and can do this safely, push un the clutch and let the revs drop to idle. What happens to the noise?

 

[Tim R]

I recently had this and it was the standard 4 blade metal fan blade. I think it was either cracking or the two pieces were coming apart (no fault was visible). As soon as I removed it the engine was much quieter and the noise and vibration were gone. I have an electric fan as well so it was not really necessary.
Try removing the fan blade and see if that makes a difference.

Tim R

 

[Scotty]

I totally forgot to reply to this thread, sorry

I was hunting for the sound and I pressed my leg against the bumper and the sound stopped. I adjusted the bolt that holds it on and so far the sound is gone. The sound would appear around 1200 rpm and vanish above 1500. Sounded like a chainsaw.

Was very happy it was just that. Thank you all for your help!