Cold start rattle 2-3 seconds then gone.

[BigLooga]

Makes sense Sapote. There is no exterior leaks, do you know if the check valve inside the tensioner is something that can be repaired if damaged or i'd be best replacing the tensioner? Thanks.

[sapote]

The main chain tensioner has a check valve to keep the oil in there, and for any reasons if oil leaked out during long hours of engine off, then lose chain will rattle until pressurized oil filled up the tensioner. One can remove and check the tensioner or leaking oil issue.

[BigLooga]

I did think about the tensioner, i called a couple of shops and it seems the tensioners are all back order... sacidou.

Wierd story i had the exact same problem with my 03 540i and the it is a known problem that the tensioner and timing chain guides can fail at higher mileage. I had the exact same issue and i changed the tensioner (it seemed it was the stock 03 tensioner) and did not fix the issue but when i performed an oil change the problem went away.

So It is kinda the reverse with the M3, if the oil wasn't so damn expensive i would probably change the oil again just for the hell of it. My oil levels are all fine, right on the mark.

[Arith2]

Tensioner would make sense to me. Those guides can break as early as 30k miles after replacement.

[Shonky]

Won't be regular VANOS rattle I'd say. That happens as VANOS changes timing I'm pretty sure - you hear it during the VANOS timing test.

[Redline]

Upper timing chain guide/tensioner.

[BigLooga]

Hi!
Had my M3 for a while, almost 7 years now, 04 6 speed tiag/imola with 145k km, love the car.

Last year after doing a routine oil change (always put bmw 10-60 same brand) i noticed immediately after that on cold starts now the front of the engine makes a rattling noise for about 2-3 seconds and then everything is back to normal. Almost seems like there is no oil somewhere for 2-3 seconds and then bang, all good.

If i cold start the car, it rattles, then turn it off, turn it back on, there is never the rattle. This rattle happens pretty much every cold start, no matter the temperature outside.

I beleive i read back then on m3forum that this was a vanos rattle but i cannot find the post as m3forum is down and can't seem to find exactly my issue here.

Vanos is stock, good power everywhere, no sign of issue other than the temporary cold start rattle.

Anyone ever had a temporary rattle on cold start that went away?

Thanks.