Not sure if this applies to the regular cooper as well. Mine is a 2008 Cooper S N14.

Here is the easiest way Ive found to lock the belt tensioner so the belt is loose without needing put the front into "service mode".








Ya need a long 21mm wrench. In fact you may need THIS Gear Wrench 21mm wrench which allows you to grab the 12 point bolt on the belt tensioner which is slightly recessed.

Its part of this large set : GearWrench 85987 5 Piece GearBox Add-On Set Metric. There is a smaller set 9-19mm which is AMAZING: GearWrench 85988 12 Piece Ratcheting Wrench Metric XL GearBox Set

They are long for added torque and have a ratcheting and deep boxed end which comes in handy all the time when bolts are slightly blocked or recessed. This is one of the best wrench sets you will ever own. Trust me. AMAZON reviews are stellar for a reason.







Anyway you remove passenger side wheel, take off the 3 plastic screw/clips and the two round plastic disks that allow access to the lights and then lift the fender cover away.

You then need to remove the plastic arm that hold the AC coolant line away from the moving pulleys. Its a 10mm bolt. This allows you to swing the long wrench. If you dont remove this plastic arm, the wrench won't fit on the 12pt belt tensioner bolt in the correct position with the freedom to swing clockwise.



Then use the deep boxed end of the Gear Wrench 21mm and slip it behind the AC coolant line like so:





You can see the wrench and the 12pt bolt on the belt tensioner through the upper hole in the fender liner...



Then push up on it CLOCKWISE. Its gonna require a lot of finger strength to get it to stay in place. You may wanna use gloves.

A second person to help push the pin into place on the belt tensioner that keeps it in service mode (belt de-tensioned) makes it much easier. If youre alone, like me, you may be able to reach with right hand and try and help push that pin in place. The pin is under spring tension so it should just pop into the correct hole, but sometimes its tricky.

To release the tensioner back into the BELT TENSIONED mode, push the 21mm wrench clockwise again while you pull on the lock pin out of the locking hole with your right hand or have the second person do this (much easier). Then release the wrench slowly and it will be holding the belt taught again.

 

nice... I always go the long way. remove the headlight, U frame of radiator support, then jacking the engine a little, then use a socket

 

Dont go the long way Mr.

 

None of the above, jack up the tensioner from underneath with a 16" piece of 2x2" wood and lock the pin.

 

Or buy the serpentine belt tool I have for sale here: https://www.northamericanmotoring.co...oner-tool.html

Which makes it super easy.

 

I shoulda known someone made a tool for that. Thanks for the info.

Does someone make a tool to help get the exhaust downpipe clamp off? That thing kicks my a$$ every time.

 

I use two screw drivers like scissors. one in each hole and pull opposite sides.