water pump removal 300SE
 

Ran into trouble taking off the fan. unalble to turn 8 mm allan nut to remove fan. Pully keep turning. looked for hole in pully to lock down and could not find. what do I do?

If it has the 103 engine...
 

it has a hole behind the pulley. You need a tool to keep the pulley from moving, as you know already...Performance products has it and probably this site too. You can also make one from a right tickness rod from Home Depot.

On the stand behind the pulley there's a pair of ridges at about the 2 o'clock position. The ridges hold the tool (3mm diameter wire with a 1cm barb at the end) laterally while you push it into a hole in the pulley You'll have to spin the fan until a hole aligns with the ridges so the tool stays in place. If you're very strong, you can lean on a piece of wood set on the belt to keep the pulley from turning as you loosen the fan. Don't get hurt!

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

The foot long metal rod that J. Hidalgo mentioned is the way to go, but since you're into it, a piece of nail about the size Sixto described will do in a pinch.

Once the hole in the back of the pulley is lined up with the ridge, lay the nail in it and push into the pulley hole.

I have a 190E, and the back of my pulley has a plastic thing that I need to remove to find this hole? But I can't see the ridge as the manual shows?

There are little (5mm?) hex bolts that hold the fan to the fan clutch. Just take the fan off that way, its a lot easier.

GregS

GregS gives you the best way to go. You don't need to remove the clutch, just the fan to get it out of your way. Then the challenge becomes the bolts that clamp the water pump to the block.

If you can find the right Snap On man and buy an FLXM13, it will greatly ease the access to these bolts.

Good luck,

Re: water pump removal 300SE
 

I did this last January. You can remove the fan blades to get the belt off. You have to unbolt the PS pump and move it out of the way to get at the lower WP bolts.

I took the radiator out but I probably didn't have to. The block drain is under the rear exhaust manifold.

The upper rear WP bolt is a PITA. I used a 3/8" drive with a u-joint at an odd angle. You can do it.

Use a little grease on the WP o-ring to keep it in place.

Get a new serp. belt while you're in there. Keep the old one as a spare.

Please report back.