Viscous Fan on C240 V6 doesn't seem to be working?

[seymansey]

Evening all,

The viscous fan on my C240 doesn't seem to be hugely effective lately - if the engine is hot, then doing the old test of attempting to stop the fan blades with a rolled up news paper seems to actually stop the fan!

My question is this - can you replace the clutch mechanism itself, do they have a certain shelf life? (Car is on 221k at the moment!) or can i pull this apart myself to see if it needs a service and clean?

 

[chubbs111]

Evening all,

The viscous fan on my C240 doesn't seem to be hugely effective lately - if the engine is hot, then doing the old test of attempting to stop the fan blades with a rolled up news paper seems to actually stop the fan!

My question is this - can you replace the clutch mechanism itself, do they have a certain shelf life? (Car is on 221k at the moment!) or can i pull this apart myself to see if it needs a service and clean?

if its the mechanical one i have just changed mine got one from wunderpartz approx £30 very easy to change took me about 10 minutes

 

[grober]

You can't really strip down the mechanism AFAIK. The viscous fluid transfer is controlled via a bi metal strip acting on a pin on the front of the coupling-- this is activated by the temperature of the air [ coming thro the radiator mainly] Sometimes these can get crudded up with road grime/oil etc meaning they can't move very well or quickly in response to changing temperature and will respond to a good clean with degreaser/wd40 and an old toothbrush, but quite often replacement is the only answer if they have lost fluid from the correct galleries-- they are often awkward to get at and if its the original its owe you no favours! They must be stored vertically when off the car. Originally made by Sachs I believe ECP probably do them.

 

[coalville126]

They are fixable, if the unit has failed due to oil loss, normally through age.

Fairly straightforward to disassemble the unit once on the complete fan/coupling is off the car.

Clean up the bi-metallic strip and remove it - just clips on. Then pull out the actuating pin. Oil can be added through that hole with - silicone oil, normally used on model car diffs. I gently heated the unit with a hot air gun to speed up the intake of oil.

Fiddly, but do-able.

edit. Above only applies to a viscous fan clutch - not electromagnetic