the tstat with this current version, I did test it and it did fully open. Of course, it's been in the car for a few years but the engine temp operates the same as it did the first day the tstat was replaced.

I think that you DO need to check that tstat - - and - - need to make those laser temperature measurements. That's two jobs now

Why are you doing that? You just told me that your current vfc was working perfectly . . "As I mentioned, it operates to MB spec. This means when unlocked the fan follows engine speed /2. When locked (I haven't measured the temp. of the rad), it follows engine speed until >=approx. 3000rpm when it releases. Then will lock again under around 1500rpm. Now, I just guess that mine is slightly under the minimum tolerance (opening at around 85C)".

That's sounds close to perfect to me; why spend the money for a new one?

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

Visit my Mercedes Web Page

Well unfortunately it leaks and I have to replenish the fluid every 6-8 Months, kind of annoying really. I'm guessing that even if I replace the seal (assuming I could find the OEM) the surround bearing would have also worn and so with even fitting a new seal, it would still leak. I hope to find a US source for a vfc so I can pay USD

I will check the tstat if I can locate a laser temp measuring tool, I think there's one at my work and at the weekend take some measurements - I'm intrigued to see what's going on in various areas of the cooling system.

I don't understand why the tstat is important when the engine is clearly hot? It's definitely fully open so why measure - I will, but am

Jim, just an observation, but sometimes we miss the beginning of your text as it doesn't appear in the top of the post makes it a little difficult to read the first sentence occasionally...



Phil

I don't have no "AUT" setting sorry.... just plain vanilla controls that progressively change from Blue to Red and a 0-5 fan setting. My R129 will start pumping heat out even when the gauge reads as low as the first line (whatever that is? 40C?) so I don't have to wait until 85C - remember my gauge is in C

Thanks for your comments - off to read some more info on tstat:

Here's a reformat of data:

129 (Vfc PN 103 200 06 22)
140 (Vfc PN 103 200 02 22)

Thermostat opening 85-89C - max opening 102C

Vfc cut-in 92-100C (air or coolant temp not defined - but the doc reads coolant every where else)

Safety cut-off at 4500rpm engine speed:
fan speed R129=3250rpm W140=3420rpm

Aux fan (1st stage):
On 100C off 95C

Aux fan (2nd stage):
On 107C off 100C (R129)
On 115C off 107C (W140)

At coolant 121C -123C Aux fan 50% duty 40 second period

Emergency off 126-128C

Coolant temp max 130C

Pressure cap opens at 1.3-1.5 bar

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

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

re-formatted info. Menu#18 (about middle of page; in BLUE table) shows the correct temps and pressures for W140.

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

Visit my Mercedes Web Page

Hi Lea.

Be aware that VFCs are EXTREMELY susceptible to permanent damage during storage and transport. Mercedes warns as follows:
============
"Transportation and Storage - Temperature-controlled Viscous Fan Couplings MUST be transported upright. For brief periods - e.g. for installation purposes, the coupling may be placed on the flange side, but never on the front side".
============
Lea, as its probably the last time that you will purchase a VFC for that car, and given the above warning, its may be a better idea to buy it from someone local to you, than to purchase it from overseas. That way, if it is found to be defective, you can at least exchange it much more quickly and with a lot less of a hassle.

In fact, this is probably what Stu experienced causing him to go through 3 new VFCs, and to find them all to be defective. (See Jim's Post No 39).

All of them may have been stored, or transported incorrectly.

Phil

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

Jim

My documentation doesn't indicate three stages in the W140 - however I'll check further on this to confirm.


Hi Phil

Yes, that's a excellent point. Oooooh, I can't stand thinking of spending 350GBP on a poxy fan clutch and so I was trying to shortcut the UK MB dealer, but now you've got me thinking - is it worth the hassle if it goes wrong? I too have read the MB TSB on this before but it never crossed my mind (rather stupidly) that the carriage from the US is completely unknown.

But as this part is made in Germany it has to be transported worldwide, I wonder how they manage to keep the correct orientation?

I'm assuming it's because the fluid can run out of he pin hole (rubbish design Sachs!)

That would make a lot of sense as there would be reduced fluid and less friction/rpm and hence higher coolant temperatures.

You've now complicated my simple logic of thought - sometimes I think "it's all too difficult!"

Cheers
Lea

Edit....

noticed a possible error in the data or something I don't quite understand.

Where I write:

Data actually says:

AC at coolant temperature in °C 121C-123C
Start of pulse. Pulse duration: 50% on time, 20 seconds on
20 seconds off

What does this actually mean??? Any thoughts Jim?

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

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

you are pushing too hard. . . where's the warning on the Sach's box; check the pictures in MENU#21. Don't see any "this side up", etc.

If the bms doesn't bend to until 100C, the vfc is not going to engage. . . period!

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

Visit my Mercedes Web Page

Jim,

The warning is a quote from Mercedes Bulletin No: 20-310. (pdf File). I just went to my garage to look at the box in which the VFC was originally packed, (I still have the box). "OBEN" means "TOP in German.

Phil

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

Ok, now I have found two documents from differing sources both referencing the same document title '20-0020' and all the temperatures I mention previously. But one shows the the tstat opening at a lower temperature.

R129/W140
tstat start opening 78-82
max opening 94

As the euro environment is generally cooler, then why open earlier?

Document 20-0020 number one is from the USA R129 DVD (so may not be specifically applicable to Euro cars), the second much more 'official' and the document was located by VIN number - so I tend to believe this one is more accurate for 'my' car. Now I wished I spotted it first.

Also, it confirms that the W140 definitely has 3 stages and the R129 only 2 - that R129 DVD is pretty poor in places! Quite confusing and misleading too


Lea

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

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

grasp of the German language: Is that MB (or Sachs) official way of stating "this side up" . . . or . . . "don't not invert" . . . . or . . ."don't ship upside down" . . . or . . . whatever??

And does eveybody appreciate "OBEN" as meaning "Transportation and Storage - Temperature-controlled Viscous Fan Couplings MUST be transported upright".

And what does "OBEN" have to do with "upright". To me, 'upright' means in the plane that it operates, ie vertically?? So where is that on the box?

BTW, Phil, let's not discount the two vfcs that I tested: so in total, FIVE (5) vfcs that didn't work out of FIVE (5). Probably a conspiracy?

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

Visit my Mercedes Web Page

Jim,

I repeated the test that you performed on the bms's, as you describe in your Web site Menu 21, under bms Heat Test. http://pages.prodigy.net/jforgione/MB_S500.html

However, I modified the procedure to reflect what I believe is a more realistic real-life scenario.

What I did do differently than you was to immerse a complete clutch, and a separate bms into a large pot of water, instead of just 2 stand alone bms's.

I inserted a digital thermometer into the water and started heating the water up. Well guess what? The bms that was still mounted in the clutch had bend by 73C, the stand alone bms had bend by 97C. I repeated this test several times with the same results. The bms that was still mounted in the clutch always bend by 73C, and the stand-alone bms always bend by 97C.

I than removed the bms from the clutch, and put both stand-alone bms's in water and started the heating process again. Both bms's now bend at the same temperature i.e. - 97C. I repeated this several times with the same results. This test is the same test that you performed, and essentially I obtained the same results that you did.

Why the discrepancy? When the bms is mounted in the clutch it is FIXED at both ends, so, when heated, being fixed at both ends, it CAN NOT expand along its longitudinal axis. It can only expand upwards (bend).

The stand alone bms on the other hand, not being fixed DOES elongate along its longitudinal axis, as well as bend-up. It is the bending that causes the fan to activate, not elongation, therefore the bms that is affixed at both ends will bend faster, as no energy is wasted elongating it. Consequently, it will activate the clutch at a lower temperature.

So in real life, if you heat up a stand alone bms, the conclusions will be invalid. Now going back to your own testing, there probably was nothing wrong with the bms's themselves.

Phil

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

Don't know for sure, but I presume that by orienting it in the wrong way, some of the oil may somehow end-up in a wrong chamber or location, and remain there permanently because of centrifugal forces. I doubt however that the oil can physically leak out because of that.

Does anyone know for sure?

Phil

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

but even though your results “appear” to be contrary to my findings, how do you explain Ritter’s results? He just mounted them on the car and tested the complete assy in the ‘good-old-fashioned-way’.

He had three ‘bad’ ones that didn’t pull in at rad temps of over 110C. That’s the real world test, and they failed. Mine didn't work either when mounted on the car. My tech has never seen one work correctly and he’s been repairing MBs for 30+ years.

So now to your experiment. Let me say that I have a few vfc here at home and I took them out to look carefully at how the bms mounts into the aluminum housing. In both cases, they both have just under an 1/8” of wiggle room. The bms is NOT pinned horizontally and can move left and right. But even if it couldn't, it does NOT expand horizontally. It expands via the coefficient of differential expansion (CODE).

Now to the calcs. The coefficient of expansion (COE) of brass and steel is 19 and 13 ppm/deg C respectively. So that means that as temperature is raised from 20C to 100C (80C difference) that the following happens: Brass expands 0.00152” and steel expands 0.00104”. The difference is 0.000480”. The (CODE) is less than 1 mill or 1/1000 of an inch and that is in the direction of the 'steel' laminant.

Even if the expansion was ALL horizontal (which it can’t be) it would be only 1.5 mills!

So the conclusions are:
1) The bms is not fixed horizontally, there’s apx 1/8” clearance end to end to end.
2) The CODE results in less than 1/1000”. The COE of brass yields only 1.5 mill and steel 1.0 mill.

I will repeat your complete vfc “in-the-kettle’ experiment but I don’t expect to see any difference. The bms is NOT captive and and the principle of "BMS" does not depend on the mechanical properties of the "mounting' device.

Implicit with any of these experiments is the fact that the bms need NOT COMPLETELY bend to open/release the clutch. And as jbaj007 pointed out, he shaves the pin about 1mill to cause it to activate with less ‘bending’ than it would require if the pin is full length. The point is that maybe at 88C (assuming it was FULLY bent at 91C) might be enough to engage the clutch.

But we are still with the quandary that 91C still corresponds to over 110C in the radiator to get 91C at the bms.

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

Visit my Mercedes Web Page

Hi Jim,

Perhaps the word "FIXED" that I used was confusing. When the bms is mounted in the clutch, it is mounted such that it can not expand length-wise. However when heated, both ends slide slightly in, permitting it to bend.

The 1/8" wiggle that you are referring to is there only after the bms has been heated-up and bend. There is no wiggle when the bms is at room temperature. At leas not on my sample.

In response to what happened to Stu Ritters Fans, I speculated on that in Post No: 64.

Phil

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

Phil

Let me say what an excellent experiment - real world and no matter what principles lay behind the differences, PROVES that the your vfc sample will lock up as quoted by MB - thanks. These results don't just 'appear' condictory, they are - fact! And are as a result of looking at the bigger picture.....

Theory is ok upto a point but you can't beat actually carrying out testing in my opinion.

My vfc construction is identical to yours Phil, in terms of horizontal play see my piccies here. The strip is under pressure and already slightly bent forcing downwards on the pin even at room temperature. There is no horizontal movement.

I know that my vfc operates as yours Phil and that my engine stays cooler due to the vfc operation only - nothing to do with tstat variations in international models. But I'm sure we're still all pondering why those W140 owners fail to see their vfcs lock before the aux fans switch on - or do they?

Maybe we should start a poll for 119 engines?

Jim, when you say before the aux fans switch on, do you mean stage 1 or 2? In my posts I'm always referring to stage 2 as when driving I can't tell if the fans reach stage 1.

Just as a technical note for the benefit of others can we refer to the 'oil' within the clutch as silicone - it's not oil. Don't wish to sound pedantic but when I stared learning about clutches this really confused me. Ta

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

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

. . I measured both of the ones I have and, at the point of being repetitious, it's about 1/8" total 'slop' when it's mounted in the 'frame' with the bms COLD.

Actually, you are confusing a piece of mono-metal vs a bi-metallic strip when each is heated. If a mono-metal strip, say brass for example, is heated it WILL lengthen by it's COE. As you increase the heat into it, it will continue to lengthen by its COE, not a lot but a little bit.

But for a BMS, the strip BENDS and BION, as it bends IT GETS SHORTER(!) as measured from the original mounted 'X' (length) dimensions. It's obvious if you think about it, since the metal is bending then it's "new" length will be shorter when heated due to the bend. SO A BMS DOES NOT LENGTHEN, it bends as defined by the CODE of the metals. And if it was 'tight' (when cold) as you describe, it will get looser as it heats!

As it bends, the pin clutch is released and vfc action is "on". Actually, one of the VFCs that I have is almost brand new and I think I'll do an experiment to shorten (as jbaj007 did) the pin clutch by 0.00X". As I remember, it engages with just a few mills of length so maybe taking off 1 mill or so at a time, then testing, I might be able to 'tune' a W140 VFC to work "properly" or maybe close to "properly". As of now, there really isn't a "properly" defined.

In MENU#20, that's the purpose of the screw and double nut: to set the height so the a smaller amount of heat would bend the bms enough to engage the clutch. It works well but trying to adjust the screw height ON THE CAR, is a challenge. However, with this new wrinkle, once the 'ballpark' length of the pin clutch is determined, it would make modifying a vfc much easier from start to finish.

I have my Cool Harness in the car and the aux fans operated at 92-93C (for the CH-92 model) and they keep my car under 98C even in 90F weather w/ AC on. So the vfc is a 'nicety' but not a necessity.

Some argue, incorrectly, that the VFC is "free" cooling. Not true since some have measured 2hp needed to turn the locked vfc. Of course, either are the aux fans 'free'! Takes the same hp to produce the extra current (25 amps) for the two fans.

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

Visit my Mercedes Web Page