Greetings!

For no apparent reason, the small idler pulley in my wife's 1998 ML320 came off (the outer part that looks like a hockey puck) leaving only the bearing. Fortunately this mishap didn't cause a catastrophic chain reaction. The belt even remained intact!

I bought a new pulley but when I checked the bolt fastening what remained of the pulley assembly it looks like I need a star-like wrench/socket to loosen the center bolt. Is this one of those Torx affairs?

What type and size of wrench/socket do I need? I thought it would be a simple Allen bolt.

Thanks!