I wonder is this can be related to my rod bearings being replaced about two months ago.
When I'm out driving around and I let off the accelerator and I am essentially rolling around 2000 rpm's I get a sound that can best be described as marbles or ball bearings thrashing around deep in my engine. The sound will go away as I accelerate but come back after 3250 ish rpm's.

It started off quiet, but has got to the point where I can hear it over the stereo am I am worrying about mucking something up.

Any ideas?

 

Have you checked the timing? Engine oil level? Rule out the obvious problems first. Usually, if a rod bearing is going bad, you will hear the knocking more under accel.

 

I would say one of 2 things. If it is running good but just loud I would say your timing chain tensioner is junk. If it is running crappy I would say your head gasket may be pooched.

Bottom end noise usually is a deep pounding not a marbles type sound. Unless you have a broken piston skirt and a piston is slapping around. I would put money on the timing chain tensioner though.

 

4 wheel drive? Is 4 wheel drive engaged? Mine sounded like that and It only did it when my hubs were locked. Yours could be something completely different, though. I hear timing chain is a cause of this sound as well.

 

Hmmm, head gasket ws done not too long ago, since than oil is doing awesome. Level is a little higher that it should be.
The 4wd seems fine, went in and out if it yesterday and it has no effect on the sound.

I'm gonna check the tensioner today, it was fine a few months ago or it would have been replaced with my HG...but that was a few months ago. And that also makes sense that the sound goes away when I accelerate thus removing any tension.
If it is the tensioner is there an easy way to tighten it up?

What about a grossly loose valve? The sound does have a bit of a mushy click to it.
I know without hearing it it is anybody's guess, but any ideas are helpful.

 

Alright, took off my valve cover and I cant seem to find any chain wear and my TC guides are still intact. So at least it seems the sound is not chain related.

Any other ideas?