Can't figure out a noise?

[dPierce]

Not sure what is creating a noise that comes and goes from under the hood of the big diesel. It does not always occur and when it does, it is directly related to engine RPM. It goes from silence at idle and inceases with RPM.



It hard to describe, but sounds the way a large gas motor sounds, like a VVVVRRRRRRRRRR, that actually drowns out the diesel caltter and almost covers the turbo whine?? This probably sounds stupid, but I can't figure out what it is, especially since it only does it while the truck is moving.



I took some people from work out to lunch in the rig and wanted them to hear the diesel's music and the turbo, but it was all masked and drowned out by this sound?



Hope somebody can make sense of what I'm talking about.

 

[Fireman]

The fan? Maybe.

Fireman

 

[Dean Upson]

Sounds like your fan sounds like mine does .



Dean

 

[dPierce]

Fan varies with RPM?

It definetly could be the fan, but it does not seem related to engine temp?



It would make sense that the fan rpm and resulting noise is in dirrect correlation with engine RPM.



Hmmmmmmmmm.

 

[Dean Upson]

Others have posted that the fan seems to come on at no particular engine temp, and the air conditioner's needs come into play as well as the engine coolant. Beats me, I have not come up with a regular pattern, but my fan comes on mostly when I am using the a/c and it sound like a small plane .



Dean

 

[JD SLVR 03]

Sounds like the Fan. It seems that if the a/c is on the fan will most likely run at low (vehicle) speed no matter what the engine temp is. Once you get moving a little it turns off. Seems to me that if you drop down to around 30mph or below the fan will come on, but not always. Doesn't always seem necessary to me but thats the way it is. I would think that it would be causing some of the low fuel milage problems. Just what I have noticed in my truck.



Jason

 

[CATCRACKER]

fan

 

[Ladders]

FAN



SOTSU!!

\\BF//



EDIT: didnt run spell ck so hope I spelled it rite

 

[Duck]

Fan

OR

A/C Compressor kicking in and out.