Description Reviews Does your car have a loud clacking sound on start up? A sound that goes away once you get oil pressure? If so, you need a new chain tensioner. This is a brand new OEM MINI chain tensioner. It's in a tricky spot to get to, but with the right tools you can have it done in under 30 min. Re-torque the plug to 45 ft. lbs., then extend the tensioner by pressing on the chain guide to unlock it. We've found cars that have overheated, had an internal part fail, or a chain guide break have needed one of these. We also replace this every time we remove a head for any type of work no matter what it is. If you need a whole kit, you can find that here. As an added benefit, we are now cryogenically treating all chain tensioners. The cryogenic “heat treating” process is where the material is cooled to approximately −185°C (−301°F) with the use of liquid nitrogen. This increases the amount of martensite in the steel's crystal structure, increasing its strength and hardness. This will in turn not allow the chain to stretch or the tensioner to fail as quickly, if ever. This keeps your motor in time better as well as quicker. Note: This part will fit all gen 1 cars. All R50, R52, and R53, Cooper & Cooper S.