Loud Noise @ Idle, Sounds Like Injectors?
 

Just this afternoon, my 7.3 (2003, 125k miles) started making a horrible noise when there is no load on the engine. I first noticed it when I let off the pedal to stop at a light. It gets better once the engine catches up at a full stop in gear. I put it in neutral and it sounded horrible again. The noise goes away when I accelerate, and I can't really hear while crusing, but as soon as I let off the pedal, it starts again. I got home and opened the hood at idle, and it almost sounds like the injectors?. If I give it throttle, it goes away, and comes back at idle. I do have an oil leak where the hpop bolts to the block, it's been leaking for 3 months. Could it be the hpop?. Any suggestions?

What exactly does it sound like? You mentioned it sounds like injectors. Like a rod knock? How loud? Are you sure the sound goes away on acceleration and isn't just muffled?

Can you tell which side of the engine it's coming from? You might think about disconnecting the UVCH wiring from each side one at a time to see which side gets rid of your noise. That would at least give you a place to start.

Broken flex plate.

This sounds like the same noise I've had going on, I thought mine was more of an exhaust leak. Flex plate? I hadn't though of that. How would you go about checking/changing the flex plate?

Hey quick...whats a flex plate and wheres it located...(I know I know...Im still learning), lol:confused:
Thx Schlepprock

Definately not the flex plate. The noise is coming from the left (driver's) side of the engine, somewhere around the middle to top side of the engine block. the noise definately goes away at the slightest increase in RPM, but it's loud at idle. Increase the idle 100-200 RPMs, and it sounds normal. It sounds to me like the injectors clacking louder, but it's hard to tell. I'm going to check the exhaust manifold today, and make sure it's tight, and doesn't have a break in it. Other than that, I'm stumped?

flex plate is what the TC bolts to....look thought the driver side wheel well around the exhaust mainfold for soot or on a cold motor start her up and feel around the manifold for exhast blowing out......maybe a small exhaust leak...

Flex plate is also called. FLY WHEEL. The big toothed gear the starter ingauges. With a Automatic , It attached the Crank Shaft to the Torque Converter.

From my understanding you can not see if is it cracked from the access cover. You have to drop tranny and look around were the FP bolts to the crankshaft.

A couple of old pictures i took with my cell phone a while back. Flex plate is the flywheel with the big grear running around the OD.

http://www.geocities.com/dirtsplat/tc1.jpg
http://www.geocities.com/dirtsplat/tc2.jpg

I agree, it doesn't sound like a flex plate. But sound can travel.
It wouldn't be a broken exhaust, it would get louder if you put a load on the engine.
If I were in your position, I would be pulling the valve cover off, then running it to see what's up.

And this does not bug the Hell out of you?

Excact symptom i have. Cell phone clips, can listen with "quicktime player" http://www.geocities.com/dirtsplat/k...timeplayer.zip

I discovered it was defenitly #8 injector by pulling the wire.

I have more of a ticking,rocker arm kinda sound, you can hear it from the driers side, but you can REALLY hear it from the passenger side.
Shlepprock

How bad it that oil leak? I think i would go after that first.

Would the leak have anything to do with oil pressure getting to the injectors. Hmmm, HPOP oil leak, injector noise, double Hmmmmm.

Yes it bugs the hell out of me, but not as much as the $1145.00 estimate I got to fix it!. That was the cheapest of 3 estimates. I've checked the o-ring seals on the HPOP, and the plug, and that's not where it's leaking. All 3 shops (1 was a Ford dealer) say the pump needs to be replaced?. I lose a quart every 2 weeks. For $1145.00, I can put a lot of quarts of oil in!.

Anyways, I took a piece of re-bar, and used it as a stethoscope, and I narrowed it down to being the water pump bearing. I then removed the serpentine belt, started the motor, and no more noise!. At least it's an easy fix.
Thanks to those who replied