I've been fighting with this front end vibration issue with my 2003 Discovery 2 for a while. The truck runs good otherwise but had this front end vibration problem since it reached it's 120k milestone. The vibration and clunking noise mainly come from the center floor of the front end and you can feel the vibration from the steering wheel and gas pedal too. It only comes out when I step on the gas pedal and accelerate. The vibration basically occurs at all speeds when the 65-80 mph range gives the worst. However, if I let go my foot from the gas pedal the vibration and the noise will become much less close to not noticeable.

I started with the wheel balancing as I noticed one of the weights on the front driver side wheel was lost. It helped a bit reducing the vibration but not much on the clunking noise; and two week ago, I put on four new tires properly balanced, still no help;
I then thought about the front drive shaft, replaced it with a rebuilt one and then a new one, neither one helped;
I also changed the brakes with all new calipers and brake pads with proper bleeding, nothing improved;
Finally, I changed the front suspension with all new springs and shocks, ball joints upper and lower on both sides, tie rod end, with a all four wheel alignment after, but the vibration and noise were still there when accelerating.

Now it seems I ran out options as I pretty much changed everything on the front end other than the differential and the steering damper.

What could be the possible causes for this front end vibration and noise?

 

Engine/transmission mounts?

 

mounts are a good next place to look and relatively cheap and easy to remedy. A bit tedious but they aren't bad to do. I go through motor mounts maybe 1-2 times a year depending on how much I get out and have them down pat. First time swapping them was a bit of an adventure. Get a swivel racheting 18mm wrench to make the driver side easier.

 

Could it be anything wrong with the front differential? How can I check?

Thanks,

 

Unlikely to be front diff.

 

I'm havin some vibrations recently as well. I noticed this week the front output flange on transfer box has some play. Hoping the nut just backed off and all I have to do is put a new nut on and tighten to spec. Might want to check that too if you didn't when replacing driveshaft. Never noticed mine and I've done shaft twice. Just push up on the back of the shaft where the joints are and you should be able to tell easily if theres any play.

Other than that, maybe hubs? is your fan in good shape?

 

Got something similar going on. Deputy suggested I remove the front driveshaft, lock the CDL and take it for a drive. If it goes away, that's your problem. Good luck!

 

2003 D2 probably doesn't have a CDL.