Should I tighten the chain Tensioner? Is this easy? I have no issues so far but have read that some loosen off and cause big bills...

 

How many miles are on your MINI? It may be best to replace it. You can change all of the timing components if you're in there as a preventative measure as well. Typically, around 100,000 miles you may develop a problem where the timing chain guides wear or break. For the tensioner, the most up to date one is HERE. Doing the timing components is a pretty time consuming job and does require you to have the necessary tools for the job. If you want help compiling all needed timing component parts let me know. For just the tensioner replacement, check out this NAM thread HERE.

 

Chain can't be tightened manually, it's kept at a constant tension hydraulically. If you plan to service / change the chain and components yourself, you'll need some special tools and at least the Bentley Service Manual (for torque specs, tightening sequence, TTY (or stretch) bolt ID), etc. The tool kit includes a "Timing Chain Tensioner" which can be used to measure chain slack --- which by itself is an easy task for a novice mechanic, and instructions usually come with the tool. I don't recommend changing the chain unless it has excess slack.

Timing chain replacement is NOT an easy task, and a good understanding of the various components involved is needed. I suggest you search threads for more info on this, and maybe start a dialog with some of those who've done it.

 

Is the tensioner loose? Can you see oily buildup around it?

If so, then yes you can just throw a quick torque on the tensioner (45 ft lbs). You will have to get the airbox and some intake piping out of the way to get a torque wrench in there.