1st Gen R53 Cooper S Tensioner Replacement

Search around for the supercharger pulley installation how-tos. Follow the directions up to the removal of the tensioner, then reverse. Find a how to that doesn't instruct you to use a 'quick' removal tool, where you don't have to pull the tensioner.

 

Basically you need to compress the tensioner (with tensioner tool/bar) and put a pin (I used an allen wrench) in the retaining hole (holds the tensioner compressed), remove the bolts, remove the tensioner. Install the new compressed tensioner, compress a little more with Tensioner Tool (Bar), remove the retaining pin, release tension.

 

Yes, four bolts, two big and two little.

A few tips: use something disposable to lock out the old tensioner arm like long bent nail, if you use the factory tool or your favorite allen wrench, it will be difficult to remove off the vehicle and spring tension will send parts flying, remove the wheel and well liner for better access, a ratcheting box end is useful on the supercharger bolt, and if it is an automatic you may need to raise and lower the engine to access the two 10mm bolts, use anti-seize on the bolts for easier thread-in with fingers.

 

The tensioners I have purchased (various cars) came compressed with a pin holding them compressed. Otherwise the spring has a lot of tension but you should be able to compress in a large vise or with a large C-Clamp.

 

Just to clarify, the spring is what causes the tension. The black "tensioner" is actually a dampener that is not under tension or compression, it just resists high frequency vibration.

Tensioner assembly (with DT tensioner stop installed on top of the "tensioner"/dampener):


Note: the thin steel piece inside the spring that has the holes in it has a half twist at the end that retains the spring. I removed the pin from the retainer and relieved most of the tension on the spring prior to removing the tensioner assembly. The retainer isn't that burly, so be gentle.

 

Are you sure you are using the correct size belt?
Is your car a JCW?
Do you have an aftermarket supercharger or crankshaft pulley?
What brand and part number belt are you using?
Did you use the same brand and P/N belt both times?
How many holes are showing on the belt tensioner retainer (coming out of the spring)?

 

Why do you think the belt is slipping?

 

Are you sure it is not a bearing going bad on one of the accesories or various pulleys driven by the belt. Maybe even one of the bearings on the belt tensioner.

 

I had to have my tensioner replaced, but it was only squeaking under idle (at least as far as I could hear). I was putting on a new pulley and belt too, so it all kind of worked together. Good luck!

 

Could be a bad idler pulley. Remove the belt, spin the pulley, and check for play.

 

The idler pulley is the small pulley that just bolted to the block. It's shown here to the right of the bigger crank pulley.

There's not a lot of stress on the serpentine belt until you get into positive intake manifold pressure (boost). I busted my crank pulley - separated the inside from the outside - but managed to drive it home gently.