I just replaced the part I ordered from mitsubishiparts.net, about 133 shipped, a lot cheaper than the 200 something the dealership wanted from me.

If it helps anyone who might be searching and read this thread in the future, I think I know why it snapped, and perhaps why it snaps for other people as well. The square drive is in a very awkward position. If you use the breaker bar/torque wrench directly on top of it with no extension, the drive isn't fully in because the bolt prevents you from inserting it all the way in. If you start from a position that won't bump into the bolt and can insert it all the way in, you hit a portion of the wheel well on the top which prevents movement, but will shatter the drive insertion on the tensioner. If you use an extension, it bumps into some of the brake wiring holders that are very firm and prevents full rotation of the tensioner. I imagine this is what happened to everyone else as well.

The solution is to use a dinky socket wrench and applying a lot of force, or just making sure you have plenty of clearance when you're rotating it so that there is nothing preventing the loosening of the tensioner.

 

Agreed! But you never know. Maybe folks just don't know their own strength.

 

I found a brand new one at discount auto parts store for $71.25.
Maker: gates
Part #:38413

Hope that help the next person that break theirs!!!!

 

Both rock auto and parts geek both sell the aftermarket OEM replacement Serp by Gates

 

I didn't know this was an issue and just completed the same job on Sunday without incident. I used an extension to come in from the wheel well through the liner and only turned the tensioner enough to insert a 5mm allen wrench into the lockout hole.

I guess I lucked out.

 

How did you pull it down with the channel locks idk how you do that ? I'm in that situation

 

I bought one at Advance Auto for (insert fuzzy memory) $40. The part was identical to OEM.