1986 GM C10 excessive fan noise

[JackBuck]

I just bought this 1986 Chev Silverado. It has a 305/3 speed Auto. It revs about 2500 at 60 MPH. The engine fan is so noisy with wind noise I can hear it over the engine. Is there away to get rid of this? I don't remember this in the past.

 

[animal]

My first thought is does the truck have a "flex" fan vs a clutch fan? I had the same issue years ago when I went to the flex style fan. Much louder.

 

[JackBuck]

How do you tell the difference between the flex fan and clutch fan.

 

[Charlie]

Standard fan (sample)

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Flex fan (sample)

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[idahovette]

When a clutch fan freezes it will make a LOT of noise

 

[JackBuck]

No it’s a standard fan. How easy is the fan supposed to move. One way it will slip on the belt and the other way I can move it by hand.

 

[1987 GMC Jimmy]

If it’s direct to the water pump, it should be pretty rigid. If it has a thermal clutch, it should have some resistance to it when it’s cold. If it’s a nonthermal clutch, it should move fairly easy. Do you have a picture? Thermal clutches do have to be replaced from time to time.

 

[75gmck25]

My truck has the HD thermal fan clutch, and it looks like a very thick/robust version of the one shown on this page (scroll down to the truck fan clutches) https://www.haydenauto.com/Featured Products-Fan Clutches and Fan Blades/Content.aspx.

The clutch has a thermal engagement mechanism that depends on a fluid coupling. At cold startup the clutch is usually fully engaged (not sure why), and you get a signficant fan roar, and then it quiets down. If I immediately shut the engine down (still cold), you can move the fan freely and it is not moving the fan belt. As the engine warms up, the fluid mechanism in the clutch starts to engage and the fan starts to move with the belt, finally reaching a point where it runs about 80% of the belt speed. The clutch is surrounded by moving air from the radiator, so at highway speeds it should disengage (cool air) and the roar should be quieter.

Considering your colder climate, you could probably use a standard duty fan clutch and stock metal fan without any issues. Shop around for prices, but the most common brand seems to be Hayden.

I do not recommend using a flex fan, or removing the fan clutch. They are okay, but a stock fan and thermal clutch work much better.

Bruce

 

[Rusty Nail]

Hayden is the best brand to run.

 

[Matt69olds]

What 75gmck25 said. There is no downside to using a thermal fan clutch. It’s along for the ride when the airflow isnt needed, engages when the temperature goes up, and pulls more air than a flex fan ever will. Not to mention quieter than a flex fan. There is a silicon fluid in the clutch that expands when it gets hot, that engages the clutch. When the engine has been sitting awhile, all the fluid collects in the bottom of the clutch. When you start the engine the clutch is partially engages until the fluid is redistributed. That’s the roar you hear when you first start the engine

 

[fried_daddy]

I love the roar of a mechanical fan on a engine.

 

[Snoots]

I'd rather hear the mufflers at highway speeds. But that's just me.