Bell Ringing Sound

96 GMC Jimmy 4x4. I have a noise that sounds exactly like a bell ringing when I hit 46 mph and as long as I stay at that speed it will do it non stop. I also hear it breifly on acceloration at different speeds. My mechanic said that it sounds like it's coming from inside the exhaust. So I had it to an exhaust place over the weekend and the only thing they could find was the gas tank shield was a little loose so they tighten that and said that he couldn't get it to do it at 46 mph. But after I drove it for a few miles it started doing it. I did have the fuel pump replaced last fall and right after that is when it started doing it but not nearly as long or as consistant as it is now. So that does lead me to the fuel tank sheild I suppose. Although it sounds to me like it's coming more from the drivers side of the engine compartment. Any thoughts are greatly appreciated.

If it is really only related to a specific speed "46 MPH" it is drive-train related. Check your U-Joints on the drive shaft. The bad needle bearings, resonating through the hollow drivew shaft can sound like a bell.

I will have that checked out and let you know if that's what it was. I appreciate the input.

It does make this sound when the vehicle is in park and I rev up the engine as well so wouldn't that rule out the drive shaft?

Well, a certain load/RPM from the engine could produce a ring in the exhaust system. I have the same problem with my vehicle, but the ringing cannot be reproduced in neutral.

Check the O2 sensors - they have an outer heat shield that can vibrate and make noise so with a mallet tap along the exhaust and listen - the cat can do the same thing if internally failing as pieces come lose. Then there heat shieds under the plugs that have small bolts mounting them - I have the drivers side one drop the rear bolt and vibrate - pain to get it back in way back/down there!