[OFB Cafe] Engine overheating

[Rick Bowers]

At Tuesday 7/15/2008 01:08, you wrote:


>From: Rick Bowers
>Sent: Monday, July 14, 2008 8:51 PM
>To: Cafe
>Subject: [OFB Cafe] Engine overheating
>
> > I do suspect the fan clutch. During my flush/fill session, it
> > appeared the fan was turning slowly, so I used a piece of 2x4 and was
> > able to stop it. I could hold it still with my hands while the engine
> > was idling with little resistance
>
>Well, then it's junk.  The fan clutch is a 
>viscous unit and it should have a fair amount of 
>viscous drag even when it's cold.  The viscous 
>clutch is similar to a torque converter on an 
>automatic transmission.  It has a pump (turned 
>by the input shaft), a stator and a rotor (the 
>part the fan blade is bolted to).  There's a 
>small bi-metallic spring that expands when 
>heated and turns a shaft that's connected to the 
>stator.  The stator either directs the oil 
>contained in the unit back to the pump 
>(freewheel), or to the rotor (which makes the 
>fan spin), depending on its orientation.
>
>With the engine hot (over 200° F) have a helper 
>operate the engine at 1,600-2,000 rpm and 
>observe the fan.  It should be making noticeable 
>noise and be spinning at approximately the same 
>speed as the water pump pulley.  If it appears 
>to be freewheeling at all at that temperature the clutch is junk.
>--
>Chris

Thanks, Chris. That's exactly what *I* thought. I 
know how fan clutches work, and it didn't seem 
normal. That's why I went to buy a new one.

It also seems to explain the problem/symptoms I am having.

~Rick

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