Drone nose?

jrollf

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I'm getting a somewhat loud 'droning' noise that can be heard throughout the rpm range but most noticable at idle. Kind of sounds like an open intake plenum, like the airfilter was missing but louder. I also seem to feel a vibration and maybe a cylinder miss at slightly elevated RPMs in neutral. Sounds like it is coming from the drivers side. I can only hear it in the cab. And it happens in neutral or moving in any gear, clutch engaged or disengaged. I can't hear it when my head is under the hood (I don't have great hearing either).

It started immediately after I removed the DMF flywheel and clutch and put in a Valeo SMF flywheel and clutch, I have a factory IDIT and I ordered the flywheel listed for an IDIT. I hear the gear roll over noise, this isn't it (still happens with clutch disengaged). While the transmission was out I also pulled my turbo down pipe, and crossover pipe, cleaned them up, painted with high temp exhaust paint, and put header wrap on them them (trying to keep cab cooler, side benefit of maybe a little less turbo lag). I've taken my intake system apart twice and put it back together. Re-positioned the down pipe to make sure I can see clearance between it and the cab. Cross over pipe doesn't go anywhere near the body. I know my body mounts were tired so I replaced them in case something was rubbing that i didn't see, no change.

My possible thoughts now:

1) bad motor mount(s), maybe I damaged a weak engine mount when jacking and shoving the transmission and engine to get them to line up? Now sound/vibration is being transmitted directly to the frame? However the sound seems to be coming from up higher/dash height... The motor doesn't seem to move around when the engine is revved.

2) IP / injectors are tired and my engine wasn't running as smooth as I thought, the DMF was hiding it and now it's very apparent with the SMF? I know the IP has at least 100k on it, if the previous owner didn't replace it, it has 220k on it. Injectors were replaced about 70k ago (G codes off the shelf from Mid West Injector Service).

Thoughts? Am i headed down the wrong path? Am I just crazy [emoji16], my wife seems to think so because I won't sell it! I tried to record the sound but the microphone on my phone keeps cutting it out, treating it like background noise. It's a daily driver and I'm worried I'm hurting it.

1993 F350 Crew Cab Dually
XLT
7.3 Factory IDIT w/Banks Sidewinder
5spd Manual
 

Thewespaul

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It started immediately after I removed the DMF flywheel and clutch and put in a Valeo SMF flywheel and clutch,

Its just the smf noise, I would pull up the carpet and install some dynamat, you will get much less heat in the cab and never know the noise is there.
 

jrollf

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Its just the smf noise, I would pull up the carpet and install some dynamat, you will get much less heat in the cab and never know the noise is there.
So I would get the noise even in neutral with the clutch pedal pressed down?

1993 F350 Crew Cab Dually
XLT
7.3 Factory IDIT w/Banks Sidewinder
5spd Manual
 

Thewespaul

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The flywheel is always spinning if the engine is on, gear rollover noise comes from the input shaft going into the trans, and that will stop when the clutch is depressed, but the flywheel can still exaggerate the engine’s harmonica or noise.
 

jrollf

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Dynamat it is! I knew the flywheel and pressure plate always spin. I've heard of the rollover noise before but not much about increasing harmonics due to the smf.

Thanks!

1993 F350 Crew Cab Dually
XLT
7.3 Factory IDIT w/Banks Sidewinder
5spd Manual
 

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