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The Bentley manual clearly instructs you to lock the cams and crank when installing or removing the tensioner.
Actually, Systemlord, the Bentley manual says no such thing. (see attatched photo from the Bentley manual)
You do NOT need to lock the cams to replace the tensioner, I replaced the tensioner and also did the full timing chain replacement later. The main way you check for chain stretch is by removing the tensioner and screwing a measuring tool into the tensioner hole (this is also how the dealer does it, without locking it). The tensioner presses against the plastic guides on the slack between the crank and the cam. The number of links on the chain between those two wheels remains the same, regardless of the pressure (or no pressure) applied by the tensioner. When you do the full chain replacement you lock the cams to keep them from getting out of alignment relative to one another and the crank so it would make no sense to do that here. Not only that, you are way more likely to screw something up trying to lock your cams in place than you would be just replacing the tensioner.
Get the Bentley manual, it is worth the $140 on Amazon. Though as far as the replacement goes, I would say that you should find someone in your local mini club who has the measuring tool. Also, chances are you will likely be doing the timing chain replacement later anyway and you can get the cam locking tool with the measurement tool as well and just have it when you need it. If your chain isn't making noise though and you dont know if it is out of spec stretch-wise, I would probably just skip it for now.
Bentley Manual instructions for removal of tensioner.
Actually, Systemlord, the Bentley manual says no such thing. (see attatched photo from the Bentley manual)
You do NOT need to lock the cams to replace the tensioner, I replaced the tensioner and also did the full timing chain replacement later. The main way you check for chain stretch is by removing the tensioner and screwing a measuring tool into the tensioner hole (this is also how the dealer does it, without locking it). The tensioner presses against the plastic guides on the slack between the crank and the cam. The number of links on the chain between those two wheels remains the same, regardless of the pressure (or no pressure) applied by the tensioner. When you do the full chain replacement you lock the cams to keep them from getting out of alignment relative to one another and the crank so it would make no sense to do that here. Not only that, you are way more likely to screw something up trying to lock your cams in place than you would be just replacing the tensioner.
Get the Bentley manual, it is worth the $140 on Amazon. Though as far as the replacement goes, I would say that you should find someone in your local mini club who has the measuring tool. Also, chances are you will likely be doing the timing chain replacement later anyway and you can get the cam locking tool with the measurement tool as well and just have it when you need it. If your chain isn't making noise though and you dont know if it is out of spec stretch-wise, I would probably just skip it for now.
Bentley Manual instructions for removal of tensioner.
Gotta say galactic is correct and not documents stand point. You pull the tensioner, the cams aren't gonna move. There still bolted down and the lobes pushing on the loaded rockers won't move. You just can't act like a bull in a china shop. Finesse plays a role in a lot of mechanical work.
Where was that thread when I needed it ;-) I just did mine (at 117K mi, 2011 cooper base).Used the "detroit tuned" tensioner which is 5mm longer but not immensely stronger byfeel. Mine was loose - it came out way too easy (as far as unscrewing it) - not as far as getting to it, that sucks. The car is butter smooth now. No codes, no issues. simple job once you remove that %$#%$#% intake hose with its bottom connector from hell.
