Clunking noise

It is the pin moving in the hitch coupler. Go to any RV parts store and get a Teflon ring that goes around the pin. Problem solved.

It's called chucking. Just from curiosity do you have a Reese hitch. A teflon ring might help but maybe not. Chucking is more or less unknown with better hitches.

Teflon Lube late is great for replacement of having to grease hitch plate and king pin plate and could cause the clunking

Other causes....

King pin and hitch jaws/bar....slop (king pin moving back/forth inside hitch)
King pin hanging up on jaws/bar......lack of grease on king pin and it can bind
Hitch head bolts.....loose not properly torqued (Head moving inside frame/supports)
Capture plate/wedge loose (depending on brand of hitch)
Hitch rails....not secured/properly torqued (Hitch moving)

5vr Nose High.....to light of pin weight

If you are towing with that 2002 F350
Last item should NOT be an issue as the dry pin weight is 2950
Dry weight of that 5vr is 2000# MORE than what your truck is rated to tow (Dry 15,300 vs MAX Tow 13,200) and the GVWR is almost what the GCWR is (19,500 GVWR vs 20,000 GCWR)

You REALLY need to go across some CAT Scales and get your weights.

I saw a note on eTrailer that mentioned one other thing: high hitching. When you hitch up the bottom of the king pin shout be 1/2 to 1 inch below the skid plate. If you hitch up with the king pin bottom higher that that it's called high hitching. I know that can also cause hitch damage.

They also mention worn king pin but that should not be a problem in your case with a new unit.

You have something not quite right. The hitch should be solid when hooked up and you shouldn't be hearing any clunking when starting or stopping. You need to have someone in the bed checking to see where the noise is coming from You've either got too much clearance around the pin, or some mounting parts/bolts are loose.

Get it checked out for your own safety. And ours too. :)

Do you have a sliding bar style hitch? Hijacker or similar? The Hijacker has an adjustment bolt of the front. Chris

Me Again wrote:
Do you have a sliding bar style hitch? Hijacker or similar? The Hijacker has an adjustment bolt of the front. Chris

It's a Curt Q20. The dealership installed it.

I'd take it back to them something isn't adjusted right.

OP, do you have a pin box that moves, like a Demco Glide or a Tri-glide. Sometimes a Mor/Ryde pinbox will clunk, but not often.

Ken

Checkng with the dealer would be a good idea. But may well be nothing really wrong with it. Not familiar with the Curt. But my previous Pulrite Super 5th and and my current Reese Elite both had about 1/8" play where the top cradle (that rocks side to side) mounted on a shaft to the base. If I pushed forward and pulled back on the cradle, it would slide that small amount. Doesn't sound like much, but when having 13-14,000 lbs doing the push/pull every time I started/stopped it clunked. The Pulrite had a nut to tighten to take the gap out. The Reese is fully welded so I had to slip a plastic disc into the gap to close it up.