I have an 08 mini S..when you start it up in the morning it sounds pretty normal for about a minute then after that it starts to get a rattle on the top end about the middle of the engine..not on the passenger side where the timing chain cover is..in between 2 and 3 cylinder..just to the right of the oil cap..if you take the oil cap off you can really hear it but it makes it run bad when you do that..another thing it sounds like its running a little rough while this is happening like a miss now and then...so then i take it out and its still running a little weird like slow response...but after a few minutes it starts running pretty much normal and the rattle is gone..you can only really hear the rattle at idle when your listening with the hood open not inside the car...it has the new tensioner so must have had timing chain done...i could use some advise before i just trade it in and get something else...thanks for any info...

 

how many miles are on it? just because the tensioner was replaced doesnt mean the timing chain was. Could be the chain slapping, but it should really just do that on a first start. Also could be the vacuum pump at the end of the exhaust cam. Also, check the idler pulley/tensioner for the water pump, it can also make a rattle noise sounding like its coming from inside the engine.