Hello, all. A '97 S420 / M119.981 here.

I'm trying to get the 8mm allen head bolt out of the center of the fan clutch. Naturally, the bolt is in there pretty tight and I'm having a heck of a time trying to hold the pulley so I can generate enough torque to finally break the bolt loose. Alldata mentions a special tool which, of course, I don't have.

I tried wedging a screw driver between the shaft and the bolts on the pulley but all I managed to do was bend the screw driver. Does anyone have a trick to getting that bolt out without the special tool? Otherwise I only see 2 options:

1. Remove the radiator, hold the pulley with the above mentioned screwdriver trick, and try and remove it with an impact wrench.

2. Button it back up and take it to the dealer/mechanic and have them do it.

I'd appreciate any tips.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles

Can you get a strap wrench on the pulley?

How do you know it is a right hand thread? A number of years ago I was trying to get the nut that holds the electric fan off my 1980 450SL. Finally realized the thing had a left hand thread.

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Lawrence Coppari

2002 SLK32 AMG
2005 Acura TL
1987 328GTS
1986 944T

Cliff_140, I can't get a strap wrench on it without taking off the belt.

Lawrence, Every write-up I've seen on the subject says its a right-handed thread. I also checked alldata and WIS and neither one makes mention of it being a left-handed thread.

It's on TIGHT!. I built the tool mentioned in this article:

http://www.peachparts.com/shopforum/diesel-discussion/74648-w210-606-serp-belt-tensioner-replacement.html#post469105

and wound-up bending the 1/4" bolts trying to break torque on that 8mm bolt.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles

Why not take the belt off and use a strap wrench on the pulley?

I always push against one side of the fan belt so that the action of the wrench tightens the belt, and that never has failed me yet.

Tom W

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Never been able to get the fan clutch in/out on an M119 w/o removing the radiator. Then again, my experience was with the W124 body. That bolt is freaking TIGHT as I remember.

I'd remove the radiator, I know that's not what you wanted to hear.

Cliff_W140 gets the prize! Since I was going to replace the belt anyway, I thought I'd give it another go. So after I removed the belt, I put a strap wrench on the pulley and a 4 ft pipe cheater on my allen wrench and the bolt came off without too much trouble!

So, here's the second part of my story. I installed the new clutch and much to my dismay, it was even stiffer than the one I took off! (Back story: I'm replacing the clutch because the BMS on the old one let go and it was engaged all the time.) So, now the car howls louder than it did before.

The clutch I bought is labeled as a "Uro", but looks exactly like this one (It cost about the same as this one too. Sorry, Phil, I shoulda checked here first ):


So my question is this: Will this thing "break in" over time and start working like it's supposed to or do I just suck it up and order the gen-u-ine unit from Phil?

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles

Whenever I had to take off the fan clutch with my old M103, I used an allen plus a deep 10mm socket on a 18" breaker bar. That (plus the special tool to hold the pulley) always did the trick - it's pretty hard otherwise with the clearance to the radiator and the torque on the bolt.

The clutch should be pretty stiff when you first start the car, but it should loosen up after a few minutes of driving (as long as the weather is cool).