muddyford911

iTrader: (1)

I just finished changing the spark plugs in my 08 F150 5.4. Went back with Motorcraft SP 515. After everything was put back together I let it idle for a while. After 5 mins or so of trouble free idling, the engine started making a really loud ringing sound. I shut it off and took the belt off just to eliminate the possibility of accessory drive noise, and it continues.
With the belt off, it still makes this ringing noise.

This is my first time changing plugs on a 3v, but I took precautions such as blowing dirt out of the holes before removing the plugs. Has anyone experienced this yet? Attached is a YouTube video.

FST150

Did you check all of your vaccum lines? Maybe you bump or pulled something off while taking the coils or plugs out

muddyford911

iTrader: (1)

I did double, and triple check all connections. I went back out just now and cranked it up again. I let it run just long enough to unplug all injectors and coils one at a time to see if it made a difference.

My two theories at this point are:
1) One cylinder is not firing, and the fuel from the injector is washing down the cylinder wall, causing the noise.

2) Some dirt fell down into the cylinder and has caused damage.

I DID blow the dirt from around the plugs before removing them, however some wet dirt appeared to be on the threads of the old plugs when I inspected them.

I've also checked the oil level, just to be safe.

vintageman

Put the rest of your stock air filter housing back on and see how it sounds. Also, check the drawer that the air filter goes in to see if the weather stripping is worn away, cheap fix, about $2 at home depot for the weather stripping. A lot of members have to replace that because of it wearing away and getting strange noises.

muddyford911

iTrader: (1)

I originally had the intake on. I took it off to remove the belt. I put everything together last night and cranked it back up. It ran fine for about 45 seconds before I shut it off, but it didn't get a chance to warm up. Earlier yesterday it didn't start making the noise until temps reached about 140 degrees.

muddyford911

iTrader: (1)

Well, I got a chance to mess around with the truck again this morning. Started with a cold engine...no noise until it started to gain temperature. Engine RPM doesn't seem to affect pitch or frequency of noise, shifting didn't either, so I climbed under the truck with a mechanic's stethoscope. Not much luck with it, however I did narrow it down to the bell housing area.

At that time I decided to drive it around the block to see how it drove. The truck idles fine, no CEL, no vibrations or rough idling. I mounted a GoPro on a crossmember near the transmission and what I found was interesting. The sound slowly fades away under load, but immediately returns when I let off the throttle. Here's a link to the video. If anyone has any input I'd love to hear it!

powerranger262

Dafuq? I haven't a clue, but I'm sticking around to find out.

screamineagle

I'm at a loss, at first I was thinking torque converter but that should change sound with engine speed.

tcp2

It's definitely following the speed of the engine. Not so much in pitch as in frequency of the harmonic. No idea of the cause though.

FST150

Maybe it's the water pump? It's random but all I can think of that is moving fluid when it gets warm. Or the power steering pump? Just random ideas, is it 4wd? Could it be the IWE system? Again just guesses