If you're using the 27mm socket to turn the engine over by hand, it is the center in the main pulley. The one at the bottom that all the other belts attach to.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Great; hoping that I never need that info.

Much appreciated.

Unbelievable; I just called Pep Boys for grins to see how much they would charge to replace the viscous fan clutch.

$475 parts and labor.

And I paid about $50 for the part.

Just cannot understand the markup on this simple job.

Ya gotta remember, most of those repair places spell the car name as "Mercede$ Ben$".

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Ok, guys; someone please 'splain me how the viscous clutch works. Does it gradually grab the fan blades so the speed gradually increases? Or does it wait until a certain temp and grab it at full speed to give the soothing roar?

That.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

What I needed to know.

Thx.