Ask away...there are no stupid questions, only stupid answers.

Simplisticly....The belt driven viscous hub drives the radiator cooling fan blades and decouples the blade assembly when the temperature of the radiated air drops. It couples when air temperature rises to a predetermined degree increasing the blade speed to closer the hub speed.
It is done by using a fluid in two chambers, centrifugal force and a pintal driven in to a metered orifice by a bi metal strip which changes it's shape (Bend.) at different temperatures.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

What HAS happened? Has anyone heard if Jim or a mod removed most of his posts? This is highly iregular. I have been following this thread for a while, and actually waded in with a question or two to try and clarify the info being presented. Hate to see it disappear... As it stands now, not too much could be gleaned from the dis-jointed, one-sided discourse.

What could possibly be the motive? Is there a question of "ownership" of the information posted?

Perhaps a mod could "restore" the lost info? Is this a possibility?

Jim seemed to be a stand-up guy... I hope there is a logical explanation for this... I hate to think it casts dispersion on a contributing member here.

Well, thanks for the ride... Hope everyone can get this sorted out.

PS hope all worked out well for the stepdaughter

I just read and posted a reply in the original thread that you have referred us to. Basically what I said was that from what you describe, it does sound as if your Viscous Fan Clutch is the the most likely culprit.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Hi Jim.

Not sure what happened, but one thing I am sure of, ALL of us would like you to come back. This thread had somehow developed a life of its own, but without your contributions, is now dying a slow miserable death.

I did not think that I'll ever say it, but I actually miss your sarcasm. Come back, and bring this thread back to life. Its only hanging by a thread. (pun intended)

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Magically, Jim's posts are back, and in the proper sequential order.

Hope Jim comes back as well, so that we can get back to the business of trying to unravel the VCF/bms debate.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Have finally made contact with Kanthal and they have promised to fax the data sheet(s) to me tomorrow - I'll attach them here for review.

I'm flying over to Chicago on Friday (watch out USA) for a little business then back to the UK for Tuesday, so we may have to wait until then before I get chance to scan and attach. Also, when I return, it will be a good time to order the new MB VFC. Sachs say this is on a 4 week lead time however I suspect MB have stock.

Lea

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'93 R129 500SL-32
'89 190E 2.6 - sold in 2002

http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg

Hi Lea,

I am extremely curious as to what you will find once you receive and install your new VFC.

I am convinced that it will work just fine.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Phil

I agree, I'm sure it will be fine too, but, the data sheet(s) will prove whether there's a difference in Bi-metallic strips or not - eliminate subjective testing, that's what I recommend.

What really surprises me is that with all the other posts/discussion in other threads that Jim often refers to, that no-one actually sort the data sheets. This still puzzles me and I guess had they done this we wouldn't be discussing it now!

Kanthal faxed me the 155TB1577 data sheet (only) today (which of course is the same as we already have) but I asked specifically for the -AGE and -GE suffix/prefix data sheets. Interesting eh?

I've emailed them asking again to clarify the meaning of the AGE/GE marking and to confirm if the 155TB1577 data sheet is cross referenced directly to both but have had no reply today. Hopefully one will be waiting for me upon my return

Lea

__________________
'93 R129 500SL-32
'89 190E 2.6 - sold in 2002

http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg

What subjective testing?? So my test of the bms only in 2002 followed by the complete VFC assy test and reported in post #110, is 'subjective'? I think not! It was done under controlled conditions and the results were documented complete with pictures.

What made you so sure that the bms were manufactured by Kanthal??? And even if they were, what makes you think that they will 'give' you the information??

Most companies prepare what my company calls "SCD", Specification Control Drawing (different companies have different names). These documents are company confidential material and specify the content of the 'part' to be delivered. They are not shared with anybody without a release from the originating company.

That's why I included the "generic" data sheets in post #159. That, most likely, is all of the data that we will ever get.

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

Visit my Mercedes Web Page

I contacted LeaUK and pberku regarding 'cleaning-up' of the thread. That would include any "attacks" but more importantly, the 'science-fiction' technical errors.

Well, there's three people and, of course, three different opinions. Suffice to say that it will stay the way it is.

I personally will make another post or two and bow out. The technical content of the thread is (has) approached 'nonsense' and I'm really don't want to try to correct it any longer. I did my best.

What technical nonsense?? Check out post #162. I purposely waited over a week to see if anybody would reply to it but nobody has.

Read my MENU#21 first and then read #162 and see for yourself.
Hint: it's not air-flow! Check out "Water vs Air Tests" in Menu#21
Another hint: You can't mount the VFC 'backwards'!

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

Visit my Mercedes Web Page

Jim

Good to see you back and contributing again.

I have made some good contacts at Kanthal and will report with further information as soon as I receive it but wasn't it I who suggested that Kanthal may not be the manufacturer? And hence my further questions to them about data sheet cross reference to the -AGE and -GE parts?

Anyway, I digress, regarding post #162 I have to say that this doesn't make much sense to me either. Not sure where Phil's coming from or going to on that one.

One thing that is interesting about the different design of the '01' part is the elongated fins. I've been pondering over this for a while. We have already agreed that due to the minimal contact area of the BMS to the actual VFC body that residual body heat from the VFC would play a negligible part in the BMS temperature; so why the need for Sachs to amend the fins?

Perhaps there is extra clearance required on the 974/975 engine (or another model that this clutch housing is used in). It looks to me as Sachs wanted to keep the surface area of the fins similar (using #menu 21 as a guide) but loose material from the front and one way was to simply extend the fins - what's your thoughts Jim?

Also, this obviously begs the question of fin purpose? More debate...

The BMS is thermally decoupled from the VFC body (by way of minimal contact) and so I suspect the fins are an attempt at stabilising the silicone fluid temperature within. Although the viscosity of silicone is relatively constant with temperature perhaps it does play a role in temp cut in after all?

I'll go and review silicone fluid's viscosity temperature coefficient...

Lea

__________________
'93 R129 500SL-32
'89 190E 2.6 - sold in 2002

http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg

I've just had the most surreal experience. I contacted Dow Corning (DC) regarding their Silicone Fluid 200 12,500 CST range and ended up in a live chat to their help desk - WOW. It really works! My questions were based on the Viscosity Temperature Coefficient of this range and am completely overwhelmed by their commitment to customer service - well done Dow Corning.

I suspect it's simply the 21st Century's answer to phone line support but it works for me

Edit:

My VFC was refilled with DC 200 FLUID but I see that DC manufactures three products specifically designed for VFCs:

DC 211 FLUID
DC Q2-1353 FLUID
DC Q5-1468 FLUID

And the fluid is brown as opposed to my 200 fluid which is clear - I wonder what the differences are? Data sheets are on request only - and of course the exceptionally friendly 'Live Chat' at DC has now closed The US must sleep at some point I guess

Lea

__________________
'93 R129 500SL-32
'89 190E 2.6 - sold in 2002

http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg

Based, on Lea's sand Jim's comments, I went back and re-read my post #162. I must agree that its total nonsense. I don't know what I was thinking when I wrote it.

The point that I was trying to make, and that is still valid, is that if the air flow around the bms is such that it does not accurately represent the air temperature that should normally be present behind the radiator, but as an example is cooler for some reason, then the bms will not bend in time.

I am assuming that that's why Mercedes changed the design of the VFC and moved it 8-mm closer to the engine. This 8 mm relocation of the VFC probably allows the ambient air temperature around the bms to correlate more accurately with the coolant temperature in the radiator. I see no evidence that Mercedes changed the specification of the bms itself

Thanks to Lea, and Jim for pointing this out to me.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

By moving the fan blades further from the fan shroud, that cuts down on the air-flow since the blades are much less effective. Since the air temperature on the far side of the radiator is much cooler than the inside portion of the radiator, by drawing less air through the radiator, the effective air-temp will be higher. So it should heat the bms to a higher temp.

Based on my 2002 test of the '00' and '01' VFCs, the bms are (were) exactly the same. But those changes still don't work in the real world. They had little (or no) effect on the actual lock-up point of the 'improved' VFC when mounted on the car.

My water tests showed that as far as the bms 'bending', it bent at exactly the same temperature. So the improvement (from 96 to 82C) had to be accomplished in their changes. But it didn't!

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

Visit my Mercedes Web Page

Jim,

As per Lea's input, it seems that the fins were re-designed as well. Anyway, its now close to 2:15AM EST here in North America. Lea being in the UK, is probably just waking up.

I on the other hand, am going to sleep.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]