2004 V8- bad fan clutch?

[dave4242]

Yesterday, when I pulled in the parking garage at work, I could hear a weird sound reflecting off concrete. Not really a ticking, but more of a rattling sound. Car was hot. I tried to reproduce it this AM with truck cold and did not hear it.

When I arrived at work (engine hot), I heard it again. Not a roar...just a rattling sound from very front of engine. I opened hood, and everything looked fine. No wobbling of fan.

I shut off engine and restarted (engine hot). For a second, it sounded quiet, then there was a loud sound (click, snap) and the rattling started again.

Is that the fan clutch? If it is, is it hard to replace in V8? Is my water pump also shot?

Thanks.
Dave

 

[TechWrench]

It could also be one of the idler pulleys for the serpentine belt. I would remove the belt and check all the pulleys and driven devices.

 

[dave4242]

It could also be one of the idler pulleys for the serpentine belt. I would remove the belt and check all the pulleys and driven devices.

Thanks. The weird thing is that when I first start the truck when warm, it is quiet. But after about a second, there is a loud noise and then the rattling begins. Wouldn't an idler pulley start making noise as soon as engine starts?

 

[fdbyrne]

V6 or V8?

Edit:: Nevermind. I see it's a V8.

 

[dave4242]

V8-4.7 l

 

[TechWrench]

Thanks. The weird thing is that when I first start the truck when warm, it is quiet. But after about a second, there is a loud noise and then the rattling begins. Wouldn't an idler pulley start making noise as soon as engine starts?

It would seem so, but I have learned to never expect the obvious. It is still easier to remove the belt and physically check all the bearings and pulleys to determine the source of the noise.

 

[rjb75]

Is your AC on when this happens? If so, it could be the compressor clutch also.

 

[gm350reratliff]

Is your AC on when this happens? If so, it could be the compressor clutch also.

The way you described it with the click-snap then the noise, sounds like when the AC compressor engages. Some compressors are louder than others.

 

[dave4242]

The way you described it with the click-snap then the noise, sounds like when the AC compressor engages. Some compressors are louder than others.

I got out of work and looked at dash. Darn AC button was on. I would have sworn it was off. Started truck. Sounded fine. Left AC on. No cold air. Got home. Making that weird rattle sound. Turned off AC. Instantly stopped.

More experimentation:

Turned ac on high. Touched the tubing that is high pressure and the one that says low pressure near where Schraeder valves are. No real major difference in temp. Maybe I could convince myself that H was slightly cooler than L.

Looked closely at pulley on compressor. Put a Mark on it to see if it is turning. It is, in fact, turning (pulley is turning, not just the clutch).

Checked temp of air coming out of vents. Passenger 78, driver 80. Outside temp is 72 today.

Looked at sight glass. Small bubbles visible at idle with ac on. But if charge were low, wouldn't compressor not run?