Front Dif mount loose

Last night I had the truck (2010, 5.4, 146k miles) up on the lift for an oil change. As I always do, I start inspecting and shaking stuff to see if it moves and found a loose front dif mount. I found it by grabbing the front drive shaft trying to move it up and down. It moved up and down....a lot. On further inspection, I saw that the nut had backed almost all the way off the bolt. The bolt head is pretty easy to get to on the left input side once the heat shield is removed. The nut, on the other hand, is a real ball buster! After two hours of trying to do it myself, I got a friend to help me. By jamming a 22mm open end wrench with everything bit of ass he could muster, my bud could hold the nut enough for me to snug it up pretty good. I plan to keep an eye on it until I can get the nut welded to the cross member. There is no washer behind the nut, so it could well be that it's supposed to be welded and maybe broke free. I couldn't tell for sure. Any way, with the mount tightened up, the drive shaft/dif can no longer be moved by hand.

I had this, was causing a clunking sound when going from D->R and R->D, dealer torqued it back down and hasn't come loose again in a couple of years.

t_j said:

I had this, was causing a clunking sound when going from D->R and R->D, dealer torqued it back down and hasn't come loose again in a couple of years.

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So many causes of "the clunk!" They are really the CLUNKS and they ain't normal.

Do you think this could cause a grinding noise when put into 4 auto? I have had grinding noises coming from the front when in 4A and the dealer cannot find the issue or replicate the issue.

aschiller98 said:

Do you think this could cause a grinding noise when put into 4 auto? I have had grinding noises coming from the front when in 4A and the dealer cannot find the issue or replicate the issue.

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I don't think it would directly cause a grinding noise, but it could cause other parts to fail that may. If the noise you are hearing is a fast ratcheting sound, like two fine-toothed gears coming together, during 2x4 to 4x4 High shift while the truck is moving, it more likely a worn IWE on one or both axle/hub interface. IWE stands for Integrated Wheel End, (a stupid name if y6ou ask me), but it's actually the vacuum operated actuator that engages the front drive axle with the hub in 4x4 mode. This Video will show you pretty much all there is to know about IWE inspection and replacement.