I have a 2014 Patriot 4X4 with the 2.4 engine and 6-speed automatic transmission that has an intermittent banging from under the body. It sounds like metal-on-metal hammering. It's intermittent but seems to happen under acceleration from a stop. The noise almost sounds like the muffler is hitting the chassis and thumping.

My friend who does my repairs, as well as his friend who is a tech at a Jeep dealer, can't find the source. They did a thorough check of things and it all looks good. My friend went on vacation, so more diagnosis is on hold for a week or two. There isn't anything similar discussed in Jeep tech lines.

Has anyone else come across this concern? Any ideas appreciated.

Thanks,
Harold

Sway bar links,rear control arm bushings

Sounds like defective motor mounts. I suspect your friend did a visual inspection and probably concluded the mounts were OK.
If the motor mounts are anything like the motor mounts on our 2.4 PT, a visual inspection lies to you. You have to pull the bolt, or pry on the mount housing to see if its actually good or not. Wouldn't take much movement to let something hit on the body structure or the floor pan.

I don't know how the rear suspension is set up on the Patriot, but the PT has a Watts Link on the rear axle, after several years of service, that Watts Link developed a bang under certain conditions. As time moved on, it became very easy to find. If the patriot is equipped with a Watts Link, with the suspension hanging, hutting one side of it with a rubber mallet will show you the source of the noise it that is it.

Thanks for the replies so far. I'll pass them along.

My guess would be lower control arms, They seem to have issues with them on the Patriots.

I got under the rear bumper today (about as far as I can get without lifting the Patriot) and shook whatever components I could reach. The passenger's side rear axle has some play and 'clunked' when I shook it. The driver's side didn't have any play at all. I think there shouldn't be any movement there. Hoping I'm onto something. Will know more in about a week when my friend can get it on his lift.

where was the play that "clunked" ? at the diff, or outer bearing ? [i'm guessing independent rear suspension ?]

I believe it's coming from the CV joint at the wheel bearing end. The bearing was making noise when I got the Jeep a few years ago and I had it replaced. The bearing only has about 17,000 miles on it.

My wife's 2012 Patriot latitude had a very similar sound. It turned out to be the aluminum heat shield above the muffler. The mounting holes on the shield had corroded away and it was just flopping around in there. I pulled it out and it quit making the noise. It hasn't caught on fire yet either and it's been a couple of years.

I had a very odd sound coming from a broken spot weld of the heat shield
on the OEM catalytic converter of a 1995 Dodge Ram 5.9 V8.

Do Chrysler dealerships still have that “Black Box” vibration and noise “Harmonic” analyzer that plugs into the OBD port and where you take the vehicle on a test drive?

if it's the cv joint, i wonder if both should be replaced while the axle is out ? or maybe a quality reman axle assembly would be cheaper ?

Grab the roof above the door. Rock the car right to left. If it makes the noise, have someone rock while you grab various components. You will feel what ever is loose. I'd be thinking sway bar links first.
Doug

My friend bowed out of working on the Jeep because he couldn't pin down the source and does not want to just throw parts at it. I got a recommendation for a 'come to you' tech. He also believed it to be in the CV axles so replaced them yesterday. There is still some noise but it has diminished. I found that the rear differential bounces up and down and is sometimes hitting the underbody. Any ideas on what to check next?

Also, were planning to go on an 800-mile trip in the next couple of days. The tech said the Patriot is safe to drive (behaves fine otherwise) and the noise only happens intermittently. I'm generally a worrier and even so I'm leaning towards going. We've been hearing the noise for well over 1000 miles. Any thoughts on what to do?

is the rear differential an independent setup ? if so, look closely at the mounting points for cracked rubber isolators.
as to the sway bar end links, [dog bones] they will feel tight attached, and the only real way to see how bad they are is to take them off and feel the play in the joint.

Powerflow, does this happen at very low speeds while driving? I had a new 2007 Charger company car that started with a front-end rattling/clunking (loud) sound very intermittently while driving at any speed, but most noticeable at very low speeds - ANY little bump you'd hit like even a crack in the cement would cause this. This started at a little over 30k miles. Had the lower control strut arms replaced - that did not solve it. Then one day we had the car up in the air while changing the oil & the shop manager came out to take a look after I described to the guys what was going on. I had even been to a well-renouned front end shop in the area, & they couldn't find anything wrong. So Ken (shop mgr.) grabs the front sway bar & on both sides of the engine cradle mounts & reefs on it. He said the two bushings were shot. Now they were not cracked or squished-out, but they were hogged-out some & they turned out to not be tight to the sway bar anymore. Once they were removed, they were ovaled-out. When the wheels hit bumps, the sway bar was sending a pretty good shock to the bushings causing the noise. I ordered some Energy Suspension bushings & this TOTALLY solved the noise. I would have never guessed this even if I was focusing on them.

The noise happens when taking off from a stop while making a turn. It doesn't happen unless you give some gas while turning, and sometimes it makes noise but most times it doesn't. The rear differential shakes and sounds like it's slapping the floor pan from underneath. The slapping noise decreased considerably with the new CV axles. The tech who did the work says it's OK to take on a long trip (leaving tomorrow) and even wrote it down on his bill. I'm thinking it may be the rear differential mount but so far I haven't been able to find any info online (like Youtube) to show the rear diff and how to change the mount.

The saga continues......

I'm still working through the noise in the Jeep. At this point, all 4 CV axles were replaced (and I got nicely ripped-off in the process...) and the noise is still there. The noise sounds like it's coming from a rotating component. There is now a banging noise when going from drive to reverse. I put the Patriot on ramps and found rotating play movement at the rear differential flange (where the rear U-joint bolts onto it) of about about 1/2"- 3/4" if I grab the driveshaft and twist it. I'm not too familiar with differentials and don't know if that's too much. Can the rear differential be the culprit?

I would be concerned about a 1/2" to 3/4" of free play on the pinion shaft.

There was a several year run where the pinion nut could loosen up and allow a lot of slop between the ring and pinion gears. When the nut loosened, the pinion would sink back into the axle assembly. When it gets loose enough, it will bind on the ring gear and start breaking off teeth, which turns into a real mess real fast.

Pull the driveshaft off the the rear yoke, and see if the pinion can move side to side, up or down, or in and out. Might put a socket on the pinion nut to see if it turns easily without moving the yoke. If that is OK, I think I would pull the cover off the diff.

Transfer case chain and sprockets like this
https://youtu.be/vxD7Cs1Az08