I agree. The pressure in your cooling system is controlled by the radiator cap. The higher the pressure, the higher the temperature at which the coolant boils. I would check the cap pressure and lower it if necessary and/or install a coolant recovery tank/system.

 

Sounds to me like it is electronic.
You don't have an electric fuel pump?

 

Sounds like gas tank venting through the cap to me. Hot day?

 

I'm putting my dollar on the fan blades.

 

OK, somebody has to say it.... maybe it is humming because it doesn't know the words!

 

I'd like to thank everyone who played "Name That Tune". If you picked the radiator as the source of the music, you've won!

I installed my re-cored stock radiator today. It was something I was planning on getting to eventually. Afterwards I took it for a short drive, making sure to get it up to temperature. The humming appears to be gone.

Apparently my truck was trying to tell me that the shiny aluminum rad looked out of place in my old beat up truck. I'm inclined to agree, the stock rad looks much better.

 

Cool beans. Can I have my dollar back?

 

I agree! I am glad you found the source of your humming. How much did it cost to record your stock radiator?

 

I always hum when I dont know the words.

Sorry, had to do that!

 

I don't recall exactly. I remember it was expensive enough that it was basically a toss up whether to have it re-cored or to just buy a reproduction. It the shop several weeks to get the job done. To be fair to them, I think most of that was waiting for the replacement core to get delivered.

 

Maybe the truck is just happy !!!!!