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!

Anyone?

Is it, the fastener you need to remove, male or female? Will the removal tool be inserted into the fastner, or will it go over/around the fastener? There are both normal (female) Torx, and reverse (male) Torx fasteners, and it's not uncommon to see either used for pulleys. Do you have the ability to post a pic? That could go a long way in getting a good answer. Let me know and I'll be able to tell you which you have, and then hopefully, what you need.

MV

This BOLT is a Torx fastener head = you need A male tool.
You can buy a standard set of male Torx bit sockets at SEARS, your local generic auto part store, and most tool stores.




Have a great day.

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I've seen both. Mainly on actual tensioners, more than the idler pulleys though. I think that the one style is from a replacement part, but it could manufacturers part supplier differences as well. In either case, Whunter is right, the tools are easily available.

MV

go this link and go to page 2, you will find all the information you need.

http://www.benzworld.org/forums/w163-m-class/1306574-serpentine-belt-change-2.html?highlight=tensioner

__________________
98 ML320 (gone but not forgotten)

Thanks, guys. FYI for those that need to remove the upper idler pulley, it's a TORX size T-50

I took a peek at my bro's c280 and I was amazed at what happened to my ML when i compared it to his- the idler pulley in the ML actually divorced itself from the bearing plus there' seems to have been a black plastic cap covering the bolt that keeps the idler pulley fastened to the carrier. That flew away too. I can't imagine how a piece as large as the outer part of the pulley assembly could not have caused one bit of damage to the radiator, fan blade, etc. when it separated from the bearing. WOW.

Anyway, when I figured it all out it was a matter of removing the looooong center bolt with the T-50 (it was torqued down very lightly fyi), pulled out the naked bearing and replaced it with a brand new idler pulley assembly ($15), lined up everything with a new belt, adjusting the spring loaded lower tensioner pulley with 17mm socket and breaker bar underneath so the belt would fit, voila....

all is right with the world again!

Thanks again guys for your replies and help!