Have a 2001 w/5.4 180,000 miles. Been noticing a buzzing noise from the the valve cover/ injector area lately. Thought it might be the alt. but noise is to the left of it. Checked the A/C pump and seems O.K. Actually the A/C pump isn't even running at when it buzzes. I shut off the heater blower fan thinking it might be the fan, it still made the buzzing sound. When you start the engine it starts to buzz but when you shut it off, the buzzing stops a second or two after the engine is completely stopped. I did this several times to make sure the engine was stopped and it was. Can it be an injector? It's been doing it for several months and getting louder. At first when I heard it at start up, it would stop after a few seconds then go away or I could shutoff the engine and restart and it would be gone. Now it is constant. You can't hear it in the cab but outside you can. Any ideas? Thanks funtwohunt

 

I don't know if the buzz your hearing or not but I started a thread a long time ago about hum/buzz I had"

https://www.ford-trucks.com/forums/6...ater-hose.html

 

wondering if maybe your air idle control is getting bad they tend to make a humming noise when they get bad.

 

on the 5.4 it is located on the back of the engine kind of tucked up under the firewall you maybe able to get your hand on it and feel if its humming

 

This seems to be a problem on my truck too. Does it sound similar a bad power steering pump howl? The hose you're referring to is behind the passenger side valve cover to the firewall, right?

If these two hoses are switched, will this be a problem?

 

You sure its not your PCV valve? Mine makes sort of a "chatter" type buzz when its runnning sometime's
Rich

 

Mine makes a power steering pump type noise. I'm going to check the PCV and the heater hoses.

 

I fixed this noise by removing a regulator inside of the heater hose that had a crimped ring around it. Some guys have replaced this hose but I just removed the regulator and Ta Da!!! Fixed.

 

I am having the same buzzing sound, dies down about 2 seconds after the key is turned off. Was wondering if anyone could describe in detail how to just remove the regulator in the heater hose so I don't have to go through the process of replacing the hoses....there is two heater hoses correct? Which one has the regulator in it?....any info would be greatly appreciated