You can rule out the fuel system by shutting the engine off while decelerating, if the noise goes away then it’s fuel related. If it doesn’t then you know it’s something else.
I cut power with the ignition when decelerating with the throttle closed down a hill about 2000 RPM in 3rd gear. No change in sound at all. Still making a hideous racket, its super loud at that RPM. Push in the clutch, and it still makes the noise, just not as loud, and it winds down with engine rpm until the engine stops turning (remember fuel is cut with ignition).
The best way I can describe it is a loud bearing growl coming from the flywheel/clutch area. Makes the sound in neutral when free revving the motor at idle, on up through 2000 rpm, clutch in or out. At idle, put it in gear, let clutch out slightly, growl goes away as soon as clutch begins engaging.
1800 RPM, clutch out, 4th gear, cruising at constant speed or decelerating its growling as loud as can be. Put under any acceleration, light or heavy, the noise goes away immediately and everything is quiet and smooth.
After driving it this morning, and cutting the fuel to see if that changed anything, I took it back to the shop where I picked it up yesterday. I told the manager lets go for a ride. He immediately recognized the sound I describe as "terrible" and I drove it around a bit and made sure he had the opportunity to hear everything.
Pull back into the parking lot, and he starts ******** and moaning at me. "Well i'm not sure i'm gonna pull the transmission again" "I've already lost so much money on this job" "you gotta understand where i'm coming from" I reminded him that the first time was his **** up, I had nothing to do with that.
He incorrectly told me the first time, that the flywheel had "already been converted". He's also now saying they won't warranty the job because I bought the parts. I mentioned that he agreed the LUK kit would fit when I read the part number. It also does happen to be the correct kit, verified by LUK's website, and other retailers. I initially discussed just having the shop order the kit (the difference was $80 vs if he ordered it or if I ordered it off Rock Auto, and he encouraged me to order it and save the money).
There are several reasons for me to believe that it is very possible the kit was not installed correctly.
#1 - They shredded the packaging the first time they did this job and aborted installing the kit, and the parts I got back in the LUK kit were disorganized. I did not count the number of bolts. I also did not move the parts at all from where they placed them in the cab of my truck, if parts were lost, not my fault. If they lost some bolts, if they lost the instructions, I would not know. The LUK parts are of a very different design than stock. I imagine the bolts might be longer or shorter.
2 - Possibility of putting in the friction plate backwards. From a cursory look at it when it sat in my truck after they opened the packaging, it seemed to look the same on both sides. LUK stamps "flywheel side" or "transmission side" on the friction plate hub in small letters.
3 - Possibility they did not torque the flywheel bolts or the pressure plate bolts correctly.
4 - General incompetence. I brought the truck in for a flywheel replacement. I showed the manager the noise it was making, and he agreed it likely a worn DMF. When the truck was apart, the same manager told me it had already been converted to SMF "long ago" and just needed a new clutch and pilot bearing. When I got it back, It was clattering like a choo choo train and a pull of the inspection cover revealed a dual mass flywheel with a ton of play in it. The 2nd time around, I am handed back a truck that sounds terrible yet the mechanic who did the work says he did not notice any unusual noises.
Right now the truck is at their shop, and I tentatively agreed to have them pull the transmission, if the kit was installed incorrectly then they will cover the labor. If there is a defective part, then parts and labor is on me. I think that is fair, but there is now an issue of trust.
Let me know what y'all think. I agree with those who say that I need some injector work. However I believe that has been ruled out by cutting the fuel. No change at all in the loud deceleration growl.
Right now I am thinking I just cut my losses and get the truck back from these guys. I paid them $700, brought them the proper kit from a reputable company, which they agreed would fit, they kept my truck for 3 weeks and it is now un-drivable. I can fix the injectors over the holidays (I do not believe this is causing the growl) and take it to another transmission shop in a few weeks.