Help with rough noise!

[Dboy3er]

I have reconditioned this E30 pretty well and drove it 3000 miles these last 2 weeks, took a road trip with it. Anyway, It is still running strong but sounds different from before the trip. It sounds rough, but idles smoothly, no oil light, power seems the same. I did find that when I hold down the oil cap with all my weight or valve cover (when its not too hot). The noise goes away! & It sounds just like before minus the rough noise.. I though it was rod bearings, or exhaust hitting the frame somehow, but I'm just dumb founded, will a vacuum leak some where cause this noise ?
 
 I know my VC gasket leaks into my 1st & 2nd Cly Spark plug wells & I do see oil slightly leaks from my oil filler cap. That shows at least my oil pressure must be good.. but as for the noise ?
 
 Any help is appreciated Thank You

[monty23psk]

check your engine mounts. Mine was a little noisier due to one going bad because of extra vibration.

[colin86325]

The bolts that hold the valve cover down have rubber isolation built into them.  This might have be the problem, or one or more bolts might be stripped out, which is pretty common.

[cristimm]

The M42 is not a smooth engine by any means.

[DesktopDave]

Upload a video to YouTube for us & post it here!

Those gaskets don't last forever, that's for sure. I'd swap in a new set. They're not too expensive, [http://www.autohausaz.com/pn/135391]here's a cheap Elring set for $26[/url]. Don't forget the fill cap, here for $5.17. You might be able to find them even cheaper...I've had mixed luck with aftermarket rubber parts. Avoid MTC and Uro, Elring is OK. They seem to last me about five years. Even the pricier 'Genuine BMW' parts shouldn't be more than $80 total. Don't over-torque the bolts, they do strip VERY easily. I always use my 1/4" ratchet to tighten them up, so I don't put too much torque into them.