Whats that noise?

[leeso]

I have been trying figure out what component is cutting in from time to time producing a noise from the drivers side of the engine bay somewhere under my feet!

It sounds like a compressor cutting in and happens when the engine is pulling hard and usually accompanies a transmission down shift.

It runs for a few seconds after the engine 'relaxes' and then cuts out. Its not the viscous fan noise which is easily identified.

There doesn't seem to be a problem but I'm just curious so over to the experts

[oemtech]

Clutch fan....

[leeso]

Whats a clutch fan??

[oemtech]

The engine cooling fan has a thermostatically controlled clutch so that it is only engaged at say 204 degrees and disengages at say 198. Takes less HP and you potentially get better gas mileage.

[leeso]

Is that different than the Viscous coupled fan?

[Max Hubrich]

I believe your talking about a fan clutch as we know it.


" Manufacturing Industry quote"
Traditional viscous clutches are controlled by a bimetallic sensor, which reacts to the discharge air temperature from the heat exchangers. This type of clutch remains the dominant type of fan clutch used on light- and medium-duty trucks and for mobile off-highway vehicles. The popularity of this product is due to its lower initial cost, the type of duty cycle and the fact that it is a self-contained, maintenance-free unit. These applications typically require partial fan speed to meet increased lower vehicle speed use and longer idling operations.



The noise will disappear when the weather gets cooler towards winter time

[leeso]

Thanks for the info. Is there anything else that may be causing the noise? - it just really doesn't sound like a fan - I can hear that cutting in/out seperately.

[tropical36]

Quote:

Originally Posted by leeso Thanks for the info. Is there anything else that may be causing the noise? - it just really doesn't sound like a fan - I can hear that cutting in/out seperately.

And not your A/C compressor, right? How about the electric fan? I'm actually thinking of a pump of sorts but can't guess what it might be, especially since we have no idea of what your rig might be and it could be a late model autopark pump for all I know.

[DriVer]

Quote:

Originally Posted by leeso I can hear that cutting in/out seperately.

This sound presents like an compressor cycling on and off in my opinion.

[Bob (WA0MQE)]

Lesso... what chassis and what year is your motorhome? If it's to old or if it's new enough you may not have electric fans. Do you have the ac turned on when you notice this noise? We might be better able to assist if we have a little more information.

[leeso]

Sorry Guys, Its a 2005 Gulfstream on a P32 chassis with the 8.1 Vortec gas engine. The AC is not on when this occurs and we dont have autopark - just the manual park pedal. There are 2 radiator mounted auxilary fans.
The noise definately has the sound of a (rat, tat, tat) compressor rather than a (roar or whirl) fan.

Hope that helps!

[BellaBo]

My M/H does the same thing with my A/C on and on acceleration. After it shifts the noise continues for about 3-5 seconds then shuts off like a water or vacuum valve shuts. It has done this for several years now only when the A/C is on. So far no failures. It stops if I turn the A/C off.

I don't know why yours is doing this when the A/C is off.

[OldTimer]

Could it be the compressor for your air horns? My Trek has a small electric compressor mounted low on the driver's side (just about under my feet) that you can hear run periodically to pump up the reserve tank.