Viscous fan possibly not working properly

**surfingooner** · 18th September 2018, 08:25 PM

Evening all, not sure if I have a problem or beginnings of a problem. I got the car back repaired after front end smash which happened over Easter, i haven’t done any long runs yet, but during the past couple of weeks the Nanocom coolant alarm has sounded, 96 degrees, set at 95, and never used to happen pre meeting with tree. The radiator has been replaced, and the mechanic did call me one day about the missing EGR. Sure all wiring is as was. When the alarm has sounded, I cannot here the fan working, when I think it should be, and it is not exactly warm in Melbourne yet.

could there be something as simple as a fuse, or any other reason why the fan is not kicking in when needed, only happening when stationary in traffic when engine at running temperature.

As soon as I get moving again, the engine cools down to usual 85 to 91 temps, and sits happily there. Are there any tests I can do or simple checks to see if there is some problem ? Hoping to head off camping in a week or so, so thought better do a bit more research. Any thoughts gratefully received. Matt.

**Pedro_The_Swift** · 19th September 2018, 06:10 AM

Lots of threads in here on testing Matt,, could even be one in TGO,,

basically on cold start the fan should roar like a banshee,, thats your first test.

**Pedro_The_Swift** · 19th September 2018, 06:12 AM

oh look...

**surfingooner** · 19th September 2018, 01:01 PM

Thank you for that, think it is no longer a 'fix' but now a 'project' - my limited abilities !! Mat.

**thai_tiger** · 19th September 2018, 01:36 PM

just a thought did the mechanic bleed the system correctly

**Pedro_The_Swift** · 19th September 2018, 05:44 PM

X2
check the bleed,, they are panel beaters, not mechanics...

**sierrafery** · 20th September 2018, 12:05 PM

IMO the best way to check the viscous unit is to try to stop the blades with a rolled up newspaper when the radiator is hot.... if it stops it's FUBAR, but make sure that the system has no air in it before that cos if the radiator is air locked and it doesnt get hot all around the fan's bimetalic switch will not lock the unit

**John_D4** · 21st September 2018, 07:02 AM

Originally Posted by sierrafery

IMO the best way to check the viscous unit is to try to stop the blades with a rolled up newspaper when the radiator is hot.... if it stops it's FUBAR, but make sure that the system has no air in it before that cos if the radiator is air locked and it doesnt get hot all around the fan's bimetalic switch will not lock the unit

Do u mean - roll up a newspaper into a round beating stick and jam it in there while the engine is running and hot?

DAMINK · 21st September 2018, 07:09 AM

Originally Posted by John_D2

Do u mean - roll up a newspaper into a round beating stick and jam it in there while the engine is running and hot?

Pretty much yea.

**sierrafery** · 21st September 2018, 12:06 PM

Originally Posted by John_D2

Do u mean - roll up a newspaper into a round beating stick and jam it in there while the engine is running and hot?

Yes, try to stop the fan with it when the radiator is hot, cos the radiant heat of it triggers the bimetalic switch(that spiral in the front of it) to lock the viscous unit. If the fan is OK it will ruin your ''stick" .... of course dont be so ''agressive'' to crack the blades but if the viscous clutch is tired the fan will stop which means it doesnt spin hard to suck air just freewheeling like when the thermostat is still closed.

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