Vibration problem progress...

[DieselViking]

So I did a few things today to try and figure out/ cure the vibration I'm experiencing at idle where my dash/ instrument cluster has a slight buzz, and I hear a steady and seemingly abnormal hum coming from behind my firewall. The engine sounds like the idle is "wavy" is the best I can describe it. The tach needle only rises and falls a tiny bit, but you can HEAR the irregularity. Anyway, I did this:

1. Changed both fuel filters: the old ones were only about 6,500 miles old. They were mostly gray colored upon removal with some darker spots on them.

Change in vibration- minimal at best. Idles a tad better, but the humming is still there.

2. Loosened the downpipe to cat bolts and v-clamp bolt while idling until change detected: this made a huge difference in exhaust vibration. Whereas before I could hold a wrench to any part of the exhaust and it would vibrate like CRAZY, now the pipes barely hum. Apparently the bolts were way overtightened! Check this if you're having exhaust trouble.

Change in vibration- just like the fuel filters, a tiny improvement, but at least now the whole exhaust system vibrates a whole lot less. Very nice improvement there.

3. Checked my motor mount bolts: checked the four 13/16 in. bolts on each side of the motor that bolt the mounts to the cradle...and guess what!!!

....while the bolts on the driver side were nice and tight...ALL FOUR of the bolts on the passenger side were loose...all barely FINGER tight!!!

So I thought I hit the Holy Grail on this one...I thought it was THE cause of my idle hum/vibe problem...I loosened the bolts on both sides and started the truck...revved it up couple times to get some body torquing. Then shut it off and tightened the hell outta those bolts.

Not really any change. DANGIT!!! Now I'm really annoyed.

The truck has no power problems when you get off idle or get on it WOT. Could it be the ICP sensor??? If you raise the rpm like 50 RPM, the engine smooths out immediately. I tried unplugging the ICP and started it, no change at all. Does that mean anything? Also, I noticed something new listening closely to the engine at idle: If I listen really hard to the engine beyond the normal diesel knocking I can hear a sort of metallic pinging sound that seems layered just below the other sounds of the engine. ???

Also, regarding my turbo moan/fart problem: what else besides driving it hard and running fuel system cleaner through it can I do to cure the probable carbonization/ turbo vane sticking I'm having? Techs chime in please. Any other ideas?

[DKR]

Not sure about the engine vibration but.......

Your turbo fart? Is it the normal one like when you get on it then have to back out of it quickly and then makes that whoop whoop whoop?

[DieselViking]

It does it when the engine is cold. I can gun it up to about 2000-2500 rpm and let off sharply and it does the "ducka ducka ducka" fart sound. You can hear it coming out of the air cleaner.

BTW, those motor mount-to-cradle bolts...how tight/ how many ft-lbs. should they be? I just tightened them down in a cross pattern about a 1/4 turn past as tight as I could get them with my 1/2 in. breaker bar. ??? Should I have driven the truck first after I loosened up both sides, and then retightened? I just loosened, ran it in park and revved it a few times.

[DKR]

Yeah, that "turbo fart" is common on the 6.0s. It is only noticeable a little with the factory air boxes, put an intake on it and you REALLY hear it!!

I don't know the ft-lbs, sorry.

[DieselViking]

Just got back from a 1400 mile roudtrip to Texas for the holiday. I had changed the fluids the night before the trip as I mentioned above. I drove the hell out of the truck on the trip. Kept the EGT's high by flooring it up a lot of hills on the highway. The buzzing/humming vibration I have at idle remains. My symptoms once more: The dash has a buzz and vibrates and you can hear the loud humming at idle. Also, you can see the tach needle rise and fall ever so slightly, and if you listen closely you can hear a "roll" to the idle...it seems to change pitch every so often. The moaning between 1500-2000 rpm I've been hearing seems a little quieter now that I'm back from the trip, but not entirely gone. Turbo fart while cold still remains.

So I'm back to the drawing board. and I played with the oil level to see if lowering it would cure the buzzing/humming vibration at idle...figured maybe if it was overfull that it might cause a problem. Lowered it to around 13 quarts. Didn't solve the problem.

I got a new ICP off Ebay for $28 . Gonna change that out and see if it does anything, if not I can resell it. I'm also gonna put some dielectric grease into the ICP connector. I unplugged my throttle pedal and plugged it back in. No luck. Gonna use some dielectric grease here too. What about the EBP sensor? The IPR? Now note that I havn't thrown a single CEL or code since I've owned the truck. Could any of these sensors go bad and not throw any codes or CEL's? Once I'm completely and utterly stumped and no one here has anymore advice I'm going to take it to the dealer and have them mess with it. Maybe I've got an injector that's not putting out at full strength? I'll let them run a power test/ cylinder/injector test. Ideas?

[2005F250]

If your still within warranty maybe you should take it in.

[DieselViking]

Yeah I know I probably should, but I havn't yet for two reasons- A. I love wrenching on things especially my own rig. B. I havn't had the time to be able to give up my truck to the dealer...drive it every day. I'm gonna have to schedule a time when I can be without the rig for a few days.