Metal chatter noise from under truck

Been having an issue with a metal chattering( chain like metal tick noise) is the best way to describe it.. The issue only happens at low rpms under a load ,or uphill. If the transmission downshifts the noise goes away. I notice the noise during 12-1600 rpms up a slight hill, until the transmission downshifts to 2k rpms.. The problem seemed to start since i dropped my carrier bearing 3/4". Anyone else have any issues like this? truck is a 2010 DCLB auto

 

3/4" drop?

Is your truck lifted?

If not, then I think you got some angles in conflict, 3/4" is a lot...

 

Yes truck is lifted.. I have all pro expos leafs

 

Mine does a similar nose in low rpms, its a heat shield rattling, goes away as i speed up too.

 

As stated likely a heat shield on the exhaust or underside of truck.

Mine corroded away on the underside of the truck so the bolt head pulled through the heat shield. Added a washer and solved the problem.

Bang on your exhaust pretty hard with a rubber mallet or shake it good to check for rattles. If nothing start to inspect heat shields for movement.

 

Thanks guys ill take a look

 

exhaust and heat sheilds are nice and tight. If i accelerate slowly right about 1800 rpms i get the knocking noise. once the rpms increase or the tranny shifts gear the noise is gone.. i also removed my CB drop and it made no difference..driving me nuts!

 

the crossmember seems good.. took a few hits around the exhaust with a rubber mallet.. everything was good.

 

Does it sound like a chain running over a sprocket ?

 

Have you checked the u-joints for wear and grease?

 

yup basically...

 

they are nice a tight and lubed...

 

Catalytic converters make noise under load and going up hills.

 

I hear the exact same noise

 

i agree with you. except the issue is now happening on flat terrain with little to no load. its is intermittent and only happens withing 1500-1800rpms

 

I am starting to lean towards a center bearing on the drive shaft. Im going to try to borrow my buddies go pro.

 

This afternoon i took the rear drive shaft out and drove around.. the noise still occured.. this rules out the rear drive shaft/ carrier bearing. I just took a crappy video but you can hear the noise. once i upload it i will post.. this is driving me nuts!

It its starting to occur more frequently now. I noticed i cant really hear it unless my windows are up. There are moments when it gets extremely load and feels like something is going to grenade. If i give it quick gas i can replicate the noise anytime.

 

Here is the video.. you can hear the noise right away and again at 14 seconds
http://www.youtube.com/watch?v=3KXX6xWul7c

 

I'm no mechanic, but that sounds like the engine knocking under a load, due to crappy gas maybe? It sure don't sound good.

 

I thought about that as well. I doubt its the motor though. I did a simple foot on brake in drive test. no noise.. the truck has to be moving. I am almost convinced its something with the torque converter or transfer case.. My next step maybe getting a tranny flush.. Im at 80k so it wouldnt be a bad idea anyway. I will try some 93 octane next tank to see if its detonation related also. From what i read it could very well be spark knock. Plugs got 15k on them.. maybe ill change them again and try cleaning the MAF