I’m trying to replace the alternator on my 2002 Focus SE Zetec-E and I can’t release the belt tensioner. I have a generic tensioner tool on loan from a shop that has the 15mm wrench head but all I’ve managed to do is put numerous dents in the head. The nut in the center of the tensioner pulley simply won’t budge.
I’m doing this from the top of the engine as opposed to from the underside. Since I don’t have ramps, this method was the only one available.
Weird Al, Are You Trying To Use “Righty Tighty, Lefty Loosey” To Loosen The Nut ?
Some engines in 2002 Foci have a square hole in the tensioner bracket. You insert a 3/8" drive socket wrench handle (breaker bar) in there and turn in the direction that takes tension off the belt so that it can be slipped off.
Other 2002 Foci apparently have the tension reduced for belt removal by turning the tensioner nut, probably what you’re talking about. However, I’m not sure that you turn it counter-clockwise (lefty-loosey). Gently try turning it clockwise (righty-tighty) and see if the belt slackens. I don’t think you’re trying to remove the nut, but rather just put tension against the tensioner pulley spring to lessen the force applied by the spring. Using a wrench handle it shouldn’t take much effort to put some slack in that belt. If you’re using considerable effort then something’s not right.
My only information says to raise the car first and remove the belt splash shield from below. You may want to consider safely raising the front of the car a couple of inches. I drive up on a couple of stepped 2x10s or 2x12s under the front tires (for oil changes) that are a foot or two in length and I chock the car’s tires so it can’t roll. Done correctly, it would be pretty hard for the car to fall off of flat, wide boards. Be careful.
CSA
I gave up on the tool and grabbed a 15mm wrench instead. If I stand by the passenger side and turn it clockwise, the belt slackens but not enough to remove the belt and it will return to full tension if I release it. Is this how its supposed to work?
OK I frown upon double-replies but in this case I’ll make an exception. The belt is off! I used the wrench and cranked on it HARD. Now the wrench is jammed against the bottom of the engine compartment and still on the tensioner nut. Hopefully the wrench won’t get in the way of removing the alternator and it will stay until its time to replace the belt.
Thank you for your help sir!
You’re Welcome, Weird Al.
CSA
I would either remove the wrench that’s stuck in place (preferred), or make very, very sure it’s locked the way it is. If it slips, it will slip hard, and there’s a possibility of bodily damage (yeah, your hands, arms, face or whatever’s near) or even breakage of the tensioner itself.
Don’t just leave it that way. Bad way to go.
Chase
The wrench slipped off while we moved the engine forward to remove the alternator. It did so without harming any bystanders. Unfortunately the serp belt slid off the crankshaft and water pump pulleys so once the alternator is back in place, we’ll have to restring the serp. That will require working from underneath.
She’s back on the road again thanks to a greasemonkey neighbor who saw me under the hood and decided to make short work of the alternator and serp belt. Thanks to everyone for their help in my first DIY endeavor.
Glad it worked out in the end. It’s always gratifying to do some work for yourself and have it come out OK. 
Chase