My fan clutch is dying, and rather than ponying up $150 for a new one, I'm considering fabbing a solid plate that takes the place of the clutch, between the hub and the fanwheel.

Has anyone done this? Seems pretty straightforward, but if someone's already done it, there's no reason to reinvent the wheel—literally.

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1964 Unimog 404.1 (wrongfully towed by the city)
1994 E320, Brilliantsilber 208k (transmission shuffled off after sudden catastrophic fluid loss)
1982 300D, Silberblau under a blue repaint 256k (sold for parts)
1995 E320 Polarweiss, 131k (sold for parts)
1995 E300D Polarweiss, 287k (totaled by drunk driver)

I did it on a w123 with conventional fan belts. Worked ok. I would not do it on a 124 though as the serp belt has a spring tensioner. Probably it would in time destroy the tensioner & the belt.

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1987 250td 160k miles English import
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Why would the tensioner be affected?

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RIP:
2011 E350 BlueTEC, Schwartz 81k (totaled by uninsured drunk driver)
1964 Unimog 404.1 (wrongfully towed by the city)
1994 E320, Brilliantsilber 208k (transmission shuffled off after sudden catastrophic fluid loss)
1982 300D, Silberblau under a blue repaint 256k (sold for parts)
1995 E320 Polarweiss, 131k (sold for parts)
1995 E300D Polarweiss, 287k (totaled by drunk driver)

The W124.131 serpentine belt system is NOT designed for the fan clutch to be locked forever = excess load/wear.

My best guess = 38% reduction of belt tensioner durability life.




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1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

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I locked the clutch on my sister's 190E 2.3 and it works great. Never has overheating issues now. Did not want to bother trying to get the electromagnetic fan clutch working again.

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You can add new silicone oil really easy as long as the bearing isn't shot. Just drill a tap a small hole, remove the pin & seal, re-fill the clutch with 10,000 weight RC car differential oil (8 bucks online), then use a set screw/locktite to seal the hole. Takes like 10 minutes. There are a couple posts about it on here as well. Not worth damaging a tensioner, I hate changing those on a 124 and they are like $100+.

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First of all... $150 is cheap for a part that will make your car operate properly. 2nd, the fanwheel paired with the clutch is not designed to spin over a certain speed, and could explode if you lock the clutch solid.

Doing a hack repair on the cooling system is being penny wise and pound foolish. Spend the $ and do it right. $150 is less more than you make in a day, and if the fan blows up and the car overheats, it will take you more than a day to fix the car again.

-J

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I got rid of my fan on my diesel and went with a E Fan for $69.Much better hardly use it,and a little more pep from engine.

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I refilled my OEM OM606 clutch with a little 7000 and a little 3000 cst oil - works good now, just be sure not to overfill it as it will never decouple then - and you may risk fracturing the fan wheel as it should never go above 3000 or something rpm.

I think you will also have to figure in the price of lost fuel economy. The main reason that clutch fans were employed was to increase miles per gallon. With the fan always spinning regardless of outside or engine temperature will always put the same drag on the engine and reduce efficiency, to what degree I cannot say.

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96 E300d

All good points. Unfortunately I don't think a clutch refill is an option, there's a good deal of play when you pull on the clutch so I think the bearing is done.

Guess it'll just be a new fan clutch. Thanks for the advice, everyone!

__________________
RIP:
2011 E350 BlueTEC, Schwartz 81k (totaled by uninsured drunk driver)
1964 Unimog 404.1 (wrongfully towed by the city)
1994 E320, Brilliantsilber 208k (transmission shuffled off after sudden catastrophic fluid loss)
1982 300D, Silberblau under a blue repaint 256k (sold for parts)
1995 E320 Polarweiss, 131k (sold for parts)
1995 E300D Polarweiss, 287k (totaled by drunk driver)

Not to mention the god awful noise. The clutches can be rebuilt for under $20 if its just the fluid.

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Fan clutch on my 616 in the 307d was designed with a locking tab. If the clutch failed, bend the tab down, locking the clutch and turning it into a fixed blade fan. Nice feature.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Not sure on a Mercedes but generally the belt tensioner is on the "slack" side of the belt, so it does not have any more wear if the fan is running or not. I know on my 89 Dodge this is so. I did replace the fan clutch with a direct drive on it as I do a lot of heavy towing and the extra cooling is well worth it. No measurable change in fuel mileage. The fan clutch in my 300d locked on it's own, no fan blades have let loose, nor has there been any change in fuel mileage. You probably would find a differance if you checked mileage very carefully over a long time.

I am not saying do not replace the clutch. You may be in a climate that you do not need to fan running most of year, so replacing it may well be worth it.

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1977 240D turbo

In my experience the 123 chassis 240D had no fan clutch, just a solid fan bolted to the water pump pulley whereas the 300D had a fan clutch. To eliminate the fan clutch on a 300D use the 240 fan and bolts. The 240D fan has a different blade pitch, shouldn't roar on acceleration and its much lighter than a locked fan clutch.

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