Noisy engine when cold starting, sometimes
 

Any common culprits that would cause a noisy cold engine? Sounds like lifters, goes away after a second or two once oil pressure builds. It doesn't always do it, either. I heard there were some o-rings and a check valve that might go bad. Would a bad tensioner also do this?

Dirty filter screens in the vanos are a distinct possibility...

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I was also going to mention Vanos system oil pressure

When my engine was cold it always ticked a bit while the lifters and chain tensioner primed, but what i noticed is it took a lot of time i was low on oil.

Where are the vanos filter screens?

N52, I'll look for the M54 and N62 in a bit. https://uploads.tapatalk-cdn.com/202...f6fd9026c4.jpg

https://uploads.tapatalk-cdn.com/202...c4a68d60cc.jpg

I believe the M54 (no personal experience) have a non-replaceable permanent screen. https://uploads.tapatalk-cdn.com/202...894dcc2e7b.jpg

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There are some times that there is too much clearance in the thrust brgs for the vanos and there is a kit available to fix it, I haven't had this happen (I don't think) and don't know how similar the sound would be but you could maybe find an example on you-tube. If it's only for a second or 2 I wouldn't worry about it much other than it might be nice just to know what it is.

My M54s both used to lifer tick pretty obvious for about two seconds when cold starting.

When my oil got low, that would last 5-6 seconds.

If this is what's happening i believe is normal.

I checked the oil and it was a bit low, added maybe a quart. Noise went away for now? Seems to have done the trick although I don't really understand it.