where can this sound come from? exhaust leak? Video!
 

Did some work on the X5 and when I put everything together, it started fine no problems. When ever I rev up the engine, it sounds like an exhaust leak. The X5 almost resembles a hemi truck. I'm thinking it might be from the intake manifold?

Sound only happens under load...when car is cruising, no sound.

Ideas? Thanks.

Work done:
Valve covers, intake mani gaskets, spark plugs, water pump, vacuum lines around the manifold (OSV area), and hoses.

https://youtu.be/6oPs8iniGFs

Any symptoms prior to the work you did? Any symptoms now other than the noise? With the engine running sparingly spray carburetor cleaner or starting fluid around the runners. If there is manifold leak the idle should change.

No symptoms before the work. Thinking about this, I realized that even if there was a leak in the intake manifold, that would not create the exhaust sound.

Maybe the drivers side valve cover gasket didn't seat properly?

The sound is only coming from the drivers side of the engine. Weird.

Check the work you did. A sound that loud should be easy to locate. Either use an auto stethoscope or anything metal. Put one end on the engine and one end to your ear. The closer you get the louder it will get.

It's not really a metal on metal sound...more like and exhaust leak.

You have a 158K on the vehicle. The video you posted does sound that the vehicle has an exhaust leak. I would look at the areas of the exhaust where the downpipes connect to the catalytic and where the center muffler connects to the exhaust pipes that go the rear mufflers. Definitely sounds like an exhaust leak.

Right, I don't hear a metal to metal sound, still works. Suggest a video taken moving around the engine bay with someone reving the engine. Hard to identify the sound from the cabin. Does the engine rev normally and hold a steady RPM at say 2500?

Since it wasn't there before your work and was there directly after your work and you didn't disconnect/loosen any of the exhaust system my guess is it is associated with the work you did.

Here is another video.

The sound is only coming from the drivers side of the engine.

https://youtu.be/QZwJ0wh-_lU

I didn't remove anything exhaust related, that's why I'm so confused. All I did was change the water pump, intake mani gaskets, valve cover gaskets, spark plugs and radiator hoses.

Car turned on the first try, but as soon as I pressed the gas, I knew that sound was not right.

The car revs up normal and accelerates fine, it's just loud and abnormal. My wife drives the X5, she keeps bugging me to take it to an indy shop but I'm scared.

I think you need to check you spark plugs. Is it possible you didn't get some torqued down enough? To get that noise and not have done any exhaust work it is the only logical solution. If you take the coil covers off you may even be able to feel the compression/air surge. Keep us posted