Very Loud Rattle from Engine *With Video*
 

There is a very loud rattle coming from my engine.

It exists while idleing and gets louder the higher the RPM's.

This began after a brake bed-in procedure ( 60-10 mph) stops.
While finishing the bed in procedure, at one point the car shut off and all indicators came on. I restarted the car and it was find for 10 minutes until I came to a light.

The noise can be significantly loud when the engine is revved.

There are no indicators on the dash, other than yellow oil light that comes on after a little while of driving.

Any ideas?

Video of rattle: http://www.youtube.com/watch?v=hLlKesS283g

You check the oil level? I hope.

Is this your 4.8 or 3.0?

Did you check the oil level? By braking hard a lack of oil can occur if the level is too low, hence the noise if the hydraulic valve clearance tuning system misses oil to work properly.

Sorry Hit Redline, I didn't see your post!

This is for he 3.0. The dipstick showed very very low oil, I just added some more. After adding the oil, the sound was barely noticable upon start up and idle, the noise returned after a very short drive low rpm drive. I'm waiting for he oil to " set" before I check the level again.

With a bit of luck, this is only the hydraulic valve tappets which are empty of oil, assuming that the lost of oil pressure (during the had braking) forced the oil in the top of the engine to drop down to the pan...

There is a procedure recommended by BMW as this is something which can occur on vehicles doing very frequent short rides, (start the engine and while keeping the transmission in neutral, accelerating the engine to 2500 to 3000 rpm during 3 minutes, then letting it idling again for 5 minutes. In some cases they recommend to do that several times with a maximum of 5.), however before doing that you have to check first where the noise is located exactly.

I am not sure I have the courage to attempt the procedure you have outlined sfcl.

I am afraid that starting the engine at all maybe causing further damage etc.

You right, this is precisely why you need tolocate the noise first. On the other hand, I'd be surprised if you got heavy damages by only having a very short lack of oil pressure, unless you had extremely low oil. When an engine is restarted after an oil change and that the filter bowl is empty, it runs about 1 to 2 seconds without any oil pressure, oil light on, too. Crossed fingers for you.

The sound seems to be coming from the left hand side if the engine, top side.
The x will be sitting about a week before anything is done.

When you said low on oil did you mean it was about 2 qts low, or only had 2 qts. (which would be 5-6 qts low)

If you were just 2 qts low I wouldn't expect any engine damage. If the sound is from the engine itself I'd pull the oil filter cap off and see if it is all together properly and if it was holding oil properly etc. I've heard of cases where a non return valve comes apart and gets stuch in the oil filter housing. So check in there for any foreign parts/materials and for any signs of metal in the oil.

It doesn't sound like valvetrain noise, but sounds like it is either from the lower rotating assembly or possible the flywheel area. And since it goes away considerably when in gear there is hope that it is in the flywheel area, but it may still be in the crank/rods etc. Did you have any transmission work done recently?