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The noise came intermittently, not easy to catch, most time came in cold below zero. It doesn't sound mechanically, it is more like air got stuck or leaked from somewhere. I can hear it pretty loud from inside the cabin when driving. This time I catch it and pop up the hood and try to locate it, but It stopped as soon as I revved up the throttle by pulling the cable. There is no warning light on the dash. The truck runs great and idles perfectly. Need help to figure out what happened. Tips and comments are welcome and appreciated.
Weird sound. I have no idea. But my philosophy on unidentifiable noises is that if it is serious, it will get louder and be more obvious as to what it is. My wild guess would be the alternator.
Totally it occurred 4 or 5 times in the past two months. I thought it was from outside somewhere until the third time I started to realize it was from my truck. The forth time it came when I stopped at a red light and disappeared immediately when I switched my foot from the brake to throttle pedal. The video was recorded at the fifth time that I could have a chance to pull aside and open the hood.
I recalled everytime it came when weather is cold at about zero or below. 15 months ago there was a different buzzing occurred but it stayed consistently unlike this one happened intermittently. That one ended up was from PCV valve, it's gone as soon as new PCV valve replaced. Don't you think this new noise may do the same with the 15-month-old OEM PCV valve?
Hydraulics make awful noises when cold, when they try to compress thicker than normal fluid.
My PSP does make a little noise when the wheels turn to ends in left or right. But this has been there for years and I am waiting to replace it until it dies. You maybe right. Next time when the noise comes again I will feel if any vibration on the PSP.
Weird sound. I have no idea. But my philosophy on unidentifiable noises is that if it is serious, it will get louder and be more obvious as to what it is. My wild guess would be the alternator.
It doesn't sound like bearing humming though. But for sure I will touch the alternator when the buzzing comes again. Thanks.
It doesn't sound like bearing humming though. But for sure I will touch the alternator when the buzzing comes again. Thanks.
Alternators hum sometimes when it is not the bearings. Way back in the 70's my 70 Mustang's 302 V8 alternator started humming at low rpm when after I first started it and put it in D or R. After stepping on the gas a little the noise went away. Sounded like a tranny whine to me. I went on a 5600 mile tour of the USA and the 50k mile drive train warranty was going to run out so I stopped at the Ford Dealer in Ft. Smith Arkansas to get it documented that the trans was humming. The service manager agreed it was the trans and a couple of mechanics agreed it was the trans. Then they got their old long time mechanic out of the office where he was drinking a cup of coffee to come and look at it. He listened inside the car and used a long screwdriver as a stethoscope to listen under the hood. Then he said remove the alternator belt and see if it still does it and picked up his coffee and went back into the office. They removed the belt and the noise wasn't there any more. The "tranny" whine was being made by the alternator. A few thousand miles later it failed.
Check the hose or hoses going to the intake/throttle body area. I think from the PCV hose on the right side valve cover?(There may have been a larger hose of the cover)? The aged hose gets sucked in and creates a "reed"/horn like situation. It's a molded hose, but you can make fuel injection or oil line work.
Let me know if you need a photo. I'll try to look at my Dad's truck this weekend if needed.
Check the hose or hoses going to the intake/throttle body area. I think from the PCV hose on the right side valve cover?(There may have been a larger hose of the cover)? The aged hose gets sucked in and creates a "reed"/horn like situation. It's a molded hose, but you can make fuel injection or oil line work.
Let me know if you need a photo. I'll try to look at my Dad's truck this weekend if needed.
MK
Thank you MK.
Sure if you can show a picture of the hose you mentioned that will be great. I will look into mine as well.
I think he's talking about the PCV inlet hose. It goes from the intake tube near the throttle body to a valve cover. The PCV outlet is in the other valve cover with a PCV valve, that hose goes around to the back of the intake manifold under the throttle body.
Weird sound. I have no idea. But my philosophy on unidentifiable noises is that if it is serious, it will get louder and be more obvious as to what it is. My wild guess would be the alternator.
Originally Posted by glc
I think he's talking about the PCV inlet hose. It goes from the intake tube near the throttle body to a valve cover. The PCV outlet is in the other valve cover with a PCV valve, that hose goes around to the back of the intake manifold under the throttle body.
If that is the case I am pretty sure the PCV inlet hose is still in good shape. It is a ridge plastic hose with one end connected to a elbow going to the rear of the throttle body the other end connected to the PCV valve sitting on the top of the passenger side valve cover. If there is leak with PCV system there must be lean code P0171 or P0174 showing up.
Thanks for your input anyways.
OK. So while looking at the engine. I remembered it was the Idle Air Control Valve making a humming noise. It was sticking and replacing it and the hose going to it solved the problem. I also changed the hoses on the PCV connector ends.
