"trader_4" wrote in message
On Tuesday, December 12, 2017 at 11:14:09 AM UTC-5, Iggy
wrote:
replying to Arthur Wood, Iggy wrote:
None of the links worked for me and my fiddling around
with them. But, if it's
sounding like something's loose and damaging everything
in its path, then
you'll have to get back in and re-do your valve cover
work. Maybe a 3/8's to
1/4 ratchet reducer, short extension, hex bit, rolled-up
tube of Threadlocker,
etc. got left behind. Even though it's a BMW, I can't
imagine you accidently
and unknowingly created a problem...unless your valve
cover work included
removing the PCV or slopping in RTV that clogged venting
and the sound is
pressure blowing the seals.

--
for full context, visit
https://www.homeownershub.com/mainte...a-1152886-.htm

I listened to it and it ain't any seals blowing. It's a
rattle/knocking
sound, like a bolt, socket, nut, etc was left in there.

Perhaps you changed something that controls ignition action?
Like, something is changing the spark timing and it is now
far
too advanced? Spark knock? Maybe? hmmm....