Cucv fan clutch engagement?

[2INSANE]

I think I read that the Cucv fan does not engage until it is at 130 degrees? Is that correct? Could I be miss informed?

If this is true, would there be a fan clutch that would engage at a lower temp?

 

[Keith_J]

That is the design temperature, it can vary since it is controlled by a bimetallic spring coil. What it does is opens a valve inside, allowing silicone oil to flow between the housing and the driving plate. When cold, the oil is trapped by centrifugal force. When the bimetal spring opens an internal valve, flooding the space between the housing and the driving plate. The clearance is small, viscous nature of the oil now couples the driving plate to the housing, transferring torque to the fan.

The fan should turn with slight resistance, WITH ENGINE OFF. It should turn easier after the engine has run for a few minutes and cold. If hot, it will be much harder to turn.

Any oil leak or locked condition is a defect.

 

[Barrman]

The fan clutch will not fully "lock up" no matter what temperature it is. I think the stock CUCV fan will get up to 70% engagement for up to 6 minutes. That is off the top of my head and may not be exact. My point is there will always be some slippage on the fan clutch.

 

[Sharecropper]

I agree with what Barrman says. Have you considered abandoning the clutch fan and using an electric fan? When fully engaged the clutch fan rob’s horsepower.

 

[Keith_J]

Clutches are more reliable and just as efficient once spooled up and freewheeling cool. I notice the roar when first started and over 2000 RPM, just for a few seconds.

Electric fans have relays, brushes and sealed bearings, I've replaced at least 5 electric fan assemblies, only 1 fan clutch.

On a low RPM diesel engine, the clutch makes sense.

 

[2INSANE]

Ok thanks for the reply’s!

I noticed the Cucv clutch is bigger then the new clutch I got from O’Rileys. Is there going to be a difference between them? I was hoping to get a clutch that engages at lower temps and rpms. I never heard the Cucv clutch engage before. Even at 130 degrees.

 

[Keith_J]

Smaller clutch will have less air movement for a given engine speed. But temperature of engagement may differ. 14032395 from the -34P crosses over to Hayden 2799 which is 41 doll hairs from the petrographic car parts dealer online.

 

[LT67]

Clutches are more reliable and just as efficient once spooled up and freewheeling cool. I notice the roar when first started and over 2000 RPM, just for a few seconds.

Electric fans have relays, brushes and sealed bearings, I've replaced at least 5 electric fan assemblies, only 1 fan clutch.

On a low RPM diesel engine, the clutch makes sense.

I use the factory clutch fan on the 406 in my 79 K20. It keeps the engine from getting too hot.... and a 406 can warmer than any other small block chevy