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I'm a diesel tech, been spinning wrenches and bloodying knuckles on these things for too long. But, like most of you I run accross something every now and again that you have not seen/heard before. This is one of my service trucks, it's a 98 F350 with a 7.3. This is a spare truck and doesn't get driven much. It's had a drivetrain (thought it was the transfer case) vibration for about 2 years? But with one truck down I used this one today, and it made a sound I have never heard before.
From what I can tell it only does it at idle, when you bring rpms up it seems to come out of it. That being said, it quit doing it twice today, ( so wait, this loud noise that sounds like the turbo is getting ready to blow up and causing everyone to stare at you at a stoplight just quit?) when I first raised the hood I was thinking an idler or vacuum/power steering pump, but it seems to be coming from the rear of the engine and seemed that the drivetrain vibration became worse, or "shorter" at a higher rpm before shifting. It is an automatic trans, 4R100 maybe, sorry haven't looked.
We have had this thing for 8 years or so and the only two things we have ever done other than GM is replaced the transfer case 20,000 or so miles ago with a junk yard one, and the center of the flex plate broke out once right after I purchased. I took the belt off and the noise is still there. I fired it up several times, at one point when fired there was a loud clunk and the noise was gone. I thought maybe torque convertor, turbo is still building boost and my experience with turbo's this would be a irregular failure. Thinking maybe the torque convertor? But the nois is so loud that it is hard to pin point when it's running. Possibly the cause of the drivetrain vibration all along instead of the junk yard transfer case. The truck only has 118,000 miles and the engine was replaced with a genuine Navistar complete reman at 85,000 before I purchased it. Sorry video will not load, it's a MOV video and so it's unsupported....thoughts? Thanks in advance
Last edited by onsiteservice; 12-12-2013 at 05:10 PM.