I purchased an ‘05 6.0 X last year. Great condition, only 152,000 miles. It has an SCT Street tune. Runs great, well maintained, no ‘abnormal’ issues considering its mileage and age.

I am not a mechanical/transmission genius but also not totally ignorant of the basics, so here is my question/issue I hope someone here has either experienced or knows about (and yes, I have spent hours reading and searching posts).

My transmission works fine, shifts fine. However, I have recently noticed a short duration noise when suddenly letting up on the gas as I was accelerating at a reasonable rate (but you have to let up because some joker gets in the way). I do not know how to describe the sound. It is not a ‘clunk’ but more as if there were some internal transmission rub. It lasts about a second. Based on what I know about transmissions I suspect it is coming from the torque converter when the transmission disengages the engine from the wheels. That is, suddenly going from under power to coasting. If I do not let up on the gas abruptly, there is no sound. Works fine.

I suspect it is something related to the torque converter because if I engage the tow/haul button, which makes the transmission not go into coast mode when decelerating (engine in compression deceleration) the sound is absent.

What should I be worrying about? I just like to understand and anticipate problems. I hate to blindly take it to a transmission shop since you know what that may mean ($) once they get in it. All diagnostic help appreciated (by the way there are no codes thrown). Thanks in advance.

 

My SWAG* is a problem with a motor mount or transmission mount.





*SWAG = Silly Wild A Guess

 

Thank you. I crawled under it this morning. Everything seems tight. No broken mounts or supports ... baffling sound, but does not seem to affect the operation. Best practice may be 'if it ain't broken, don't fix it'. Still, OCD wants me to know so all suggestions appreciated.

 

I have similar issues with mine. A 2002 4R100 in the V10. I "feel" things through the gas pedal at different stages of acceleration. I have read there are issues with the torque converter in my particular transmission, but it could be many other things as we have no idea how the previous owner treated the Transmission. We are getting ready to have a Transmission shop do an inspection/diagnosis. This rig is too heavy to be messin' and guessin' with the Transmission.

 

As I understand it, the most common cause of transmission failure on the Excursion and super duties is grounding issues. What happens is a large amount of electricity generates within the transformation and this causes the internal parts to essentially weld together.

The prevention is simple, it is recommended to add additional grounds from the transmission to the chassis. One at the bell housing and potentially one at the tail end. You may also want to replace the ground from the body to the frame that is just under the front passenger seat with a heavier gauge ground.

There are are a couple YouTube videos that explain this.