Peter,

I have one of those W124 CD manuals but I cannot find anything in there when I want. I remember reading something about it once before, I think on the function of the thermostats. Can't find it now though, but it did not go into the guts. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

OK, here's the deal:

The reservior is in front of the working section, and is slightly larger in diameter. The hole covered by the valve is about 2/3 of the distance from the center to the rim of the clutch (on the W108, may be different on others). I assume, although the diagram does not show it, that there are bleed orifices in the outer rim of the working chamber.

At rest, the fluid will partially fill both chambers on the bottom of the clutch. As it spins, the fluid will first flow out evenly, then work out the bleeds to the reservior chamber due to the difference in diameters. It will probably fill most of the space there.

So long as the hole is covered, most of the oil will stay in the front reservior, and the fan will turn slowly. Some leakage takes place, so the fan doesn't actually freewheel.

When the pin moves back and the hole is opened, the centrifugal pressure will force the oil out from the reservior to the working chamber down to the level of the hole. This will drag the fan to high speed, about engine speed up to 3000 ro 3500 rpm. Fluid will flow through the workign chamber back into the reservior constantly so long as the pin is out. When it comes back in, the hole is closed and the oil pumps back in. If the fluid is so low that it never covers the hole, the clutch won't work hot, but will still drag up to speed cold.

Pretty neat, in my book. I'm definitely going to test the 280 soon, and buy the oil to fix it if it is shot.

A freewheeling fan would make me think the clutch is empty.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I went to the Toyota dealership today to purchase some of the silicone. The 10,000 cst kind. They had to order it.
I have replaced the clutch in my car once and could not tell a bit of difference before or after. Makes me think the new one I bought did not have any silicone in it. It did have on the box to keep in an upright position but was sitting on my porch laying down when I came home, so I doubt that any are really kept in that position during shipment or for that matter in the warehouse. Like a dummy, I threw my old one away. I plan to try to fix my clutch as soon as the silicone comes in and will post the results. This clutch has never allowed the fan to spin as to hear the air flow. It has always been easy to turn by hand. As a matter of fact, with a hot engine running I can grab the fan with my gloved hand and spin it the opposite direction. I also have a 1999 Chevrolet pickup and when the engine is started and cold, you can always hear the fan roar for several seconds then quit. If the engine is hot, you can definately hear the fan come on strong. I think Mercedes clutch units are in need of better design as there are lots of post about bad fan clutches. I talked with the Chevrolet dealer and they replace very few.

__________________
1995 S-350
370K + SOLD
1952 220B Cabriolet
39K kilometers + SOLD
1998 E300D
310K +
2012 E350 BlueTec
120K

I've seen a few bad chevrolet clutches, too. I suspect the dealer doesn't see that many, because not that many people use the dealer for service out of warrenty or for used cars, simply becuase they are so expensive.

The ones I've seen that were dead were at the same type of milage we see on the MBs -- 150,000 and up.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks, Peter. It is beginning to make sense. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Jim:

Most things are easy once you figure them out........ It's getting there that give me the headache!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Check this link out, I think the explanation is wrong as there is no friction involved, but the pics help understand.

http://www.senator24v.co.uk/viscous.htm

Car is a Vauxhall Senator (UK version of similar Opel) but note the clutch is made by BEHR, OE suppliers of cooling parts to MB.

__________________
Mick J
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)

Folks,

I'm finally getting ready for my a/c compressor replacement and will need to at least move my belt out of the way. I'm debating if I can just loosen the belt and move it aside or need to remove it. I FINALLY have a sunny day here and can take a look at it in good light. I expect there should be a way to just loosen the tensioner to slide the belt out of the way for a while.

If I need to remove the belt, the web page in the reply above shows the allen head fan bolt as left hand thread. Is it left hand thread on our Mercedes ('87 SDL) as well?

Chuck

Right hand so far as I know. Certainly don't remember it as left hand, anyway.

To loosen the belt on the 300SDL, you need to find an 8mm or so bar. Put it in the hole on the side of the tensioner swivel, remove the nut on the retaining bolt (goes front to rear), the relieve tension by pushing down on the bar. Push bolt out and let the tensioner swing down and come loose.

You may be able to just slip the belt off the AC pulley rather than completely remove it. Just leave the loop up to the the tensioner in place.

I recommend taking the fan off to replace the belt, very difficult to get the belt up between the crand and water pump pulleys otherwise.

I'll dig up the procedure for the M103, since I have to anyway -- planning on putting a visco clutch and belt on the 300TE this weekend. Did the tie rod and charged the AC last night, will see how long the AC last, I think I need new o-rings on the compressor lines.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Psfred,

Thanks, exactly what I was looking for. I took at peek at it today, and with your explaination I think I've got it.

Now to catch up on the other jobs backing up. We're going a 1500 mile vacation trip this Friday (hey I'm being layed off Thursday, so declare vacation time!). Doing an o/c and rotate on our Ford conversion van revealed the need for front brakes. I also need to flush the tranny on my mustang, and an oil change / starter rebuild on a boat (chevy big block...). Well I have enough to keep me off the streets for a while.

I received my compressor and receiver/dryer today. All looks to match what is in there. I got it form the company that had the Ebay auction. Given the $500 difference in rebuilt vs new, I'm going to try the rebuilt. I'll let the folks here know the results. The previous owner swapped to r134 about 100K ago and this compressor just died as I have mentioned. I'll have to track down the records to see if that was a new/rebuilt compressor installled at that time. Scheduling the repair time with my A/C expert and will flush, flush, flush, .... and hopefully repair soon. With days off during the week now I can get more done at home.

Thanks again to everyone. Going from domestic iron to the Mercedes world is a bit intimidating sometimes.

Chuck

The other type of coupling used on MBs (whole assembly bolted on to water pump spindle with a big nut instead of a through bolt) is definately LH thread.

__________________
Mick J
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)

brand name of the 'oil' you used????

BTW, outstanding job. You made everybody else understand the VFC even if they didn't want to!

Have used a 'mechanical' means to make the clutch work at a lower temp because the bm strip doesn't bend enough until very high engine temperature. My page (click 'www' icon below), Menu #20.

But by shortening the valve 'pin', even a slight movement of the mb strip will engage the VFC, so it effectively works at 90C.

Also kudos to everybody in this thread with the great links and explanations.

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

Visit my Mercedes Web Page

Well, I just got through fixing my visco clutch. Did it while pulling a vacuum on my a/c. See thread Transmission Slipping in Reverse - Repair mine or Mercedes Rebuilt??
I purchased the Toyota 10,000 silicone and inserted it into the clutch by way of the pin hole that the metal ring pushes against. The metal ring is easy to remove after you cut some of the silicone away that holds it to the unit. It will slide sideways on the tab side that has the two prongs. Once it is removed, you can pull the pin out with pliers. I used a hypodermic needle to insert the fluid but had to take the needle off because the fluid would not go through the needle very well. Just get one with a smaller end where the needle attaches and don't use the needle. Like feeding a baby. Mine held about 1.5 bottles. The clutch comes on strong when first started and then slows down. You can definately hear the difference in fan noise when it is on. It has never worked like this before, even when new. I am very pleased. I just don't know what keeps the silicone from gradually leaking out of the pin hole as there is no internal o-ring. Just the outer rubber washer. I guess that is why so many of them run out of silicone.

__________________
1995 S-350
370K + SOLD
1952 220B Cabriolet
39K kilometers + SOLD
1998 E300D
310K +
2012 E350 BlueTec
120K

Oh, by the way Jim, I looked in some literature at the Mercedes dealer and the clutch is supposed to come on at 71 degrees centigrade ambient air which is supposed to be between 90-95 degrees centigrade coolant temperarture.

__________________
1995 S-350
370K + SOLD
1952 220B Cabriolet
39K kilometers + SOLD
1998 E300D
310K +
2012 E350 BlueTec
120K