Just to follow up on*fixing the VCF:
Your discourse on your web page was quite helpful and gave me the impetus to get the thing done. However, I could not find any way that seemed "proper" to fix the fan pulley while trying to remove the Allen bolt holding the VCF. In fact, when I got it apart, I could not find any way to restrain the pulley, even being able to access both sides of it for inspection. What I did do was to hold it very gingerly with a pair of vice grips, being very careful not to deform the pulley and then fix the vice grips with a screwdriver. It's not elegant, but it worked.
I found that the bimetallic strip was not as pictured, but was rather more of a equilateral parallelogram with the fingers at the ends to fit under the retainers. There was a cross bar over the pin on the VCF with an adjusting allen bolt in it which bears on the VCF activation pin. The adjusting bolt was frozen and too delicate to muscle out, so I ground the bottom nib off and the VCF adjusting pin now appears to be fully extended.
When the VCF pin is fully extended, does it lock the fan mechanically, or through the viscous function, i.e., with pin fully extended, should I be able to rotate the fan independently of the pulley?
BTW, while I was at it, I figured out how the radiator comes out. It's like the one you show on your 500 and the thumb screws in the middle of the posts which pierce the upper radiator support member unscrew and allow the radiator to be lifted out at the bottom, I believe.

Yes, there's a special tool for that but vice-grips are just as good . . . in other words, whatever works!

Sorry, don't understand what you wrote . . .

The pin pushes on an internal 'switch' (clutch) when the bms is cold (ie no bend) and DISABLES the VFC (It's not "VCF" . . but VFC for "viscous fan clutch"!). When the bms reaches it's 'bend' temp (100C or more), the bms now is bent and this releases the pressure on the internal clutch causing silicone to flow and LOCK-UP the fan.

If you mean that you ADDED the bolt/nut as shown in MENU#20, then the answer is "yes", the VFC is fully engaged IF there is silicone in the VFC. If not it won't do anything.

You will KNOW that it is locked as soon as you start the car; the 'swooshing' from the fan will immediately alert your ears. It was because of the constant air-noise that I modified the method.

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

Let me try again on the bms. It is a diamond shaped strip with nibs on each end to fit under the holders on the VFC housing. The diamond is annular so that a similar but smaller diamond is cut out of the center producing a diamond shaped device that is hollow in the middle. In fact, the area over the pin would not have any bms above it if there were not a cross bar incorporated. A set screw is set in the cross bar exactly over the clutch pin.

I don't see any difference in the behavior of the fan with the modification I made. Given the configuration I have described, there is no place to make the modification you suggest as there is virtually no bms with material on the center line so that you could properly lift it off the pin. This is really difficult to describe and I'm not going to go out and take it apart so I can take a picture. I included a drawing for clarity (I hope). Of course, this is a rather crude drawing—the ends are cut off to fit under the retainers on the VFC. The area between the two diamonds is the bms.

Regarding the result: i don't see any difference in the behavior of the fan, so I think that the viscous is working. That is, I don't get any whooshing and the fan does not lock up with the pulley as far as I can tell. The set screw which I ground off does not depress the pin on the vfc. Does the VFC nit die and just not work?

Thanks again, RWA

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Tnx for describing your VFC mods.

Some background info which may be missing: the purpose of the mod is to 'force' the VFC to be fully engaged by mechanically raising the "pin-clutch" so that fluid is forced to lock up the fan full time independent of engine temperature.

So with that said, if you 'raised' the BMS up as shown in my pic (Menu#20), then the VFC should be engaged, full time and should turn the fan at the same speed as the engine independent of engine temperature. So the fan should make a "swooshing" noise.

If there's NO difference, then that could be two (2) things;
1) you didn't really raise the "pin-clutch" up enough to cause it to engage . . .
or . . .
2) you DID raise it up enough but it's out of silicone fluid, so it can't 'lock-up' the fan. It can be fixed by filling it with silicone fluid (from 'toyota')

If it's either of the latter, I'm sorry for your wasted time. . .

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page