2010 4.0 v6, manual trans,4x4


So, feels like I was just on here posting about a something (separate issue) and all the sudden there’s something else that pops up. I have a very strange noise coming from somewhere In the front lower half of the vehicle that makes a noise like a grinding low pitched marble rattle type sound. I’ll try to describe when it occurs and what it sounds like the best I can. So after trucks been sitting for at least 8 hours (based off a work day) when I start it up it doesn’t make the noise right away but takes about 5ish or so seconds to start and it’s a weird sound to describe but it’s like a grumbly metallic sound that continues for about a Minute until the truck warms up a bit, and then it only occurs when truck has load on it taking off from low rpm’s.. I’ve tried to replicate it and hear it from just revving the engine with it in neutral but I can’t hear it at all. Then I’ll put it in gear and go for a drive and without fail I can hear it al the way from about 1000-2000ish rpm and then it seems to go away but I also could be wrong about that since it’s hard to hear. Had an experienced mechanic take a quick look at it after I described to him what was happening I maybe though the timing chain as I know these trucks can have issues with them but when I started it up he assured me that it’s not the timing chains as he’s heard a few of em. Of course though when I go to show him the noise was quieter than usual and we didn’t go on a test drive because there was no time but he said what I was describing could possibly be a number of things but like I said we didn’t have the time to diagnose things and now he is on vacation hence why I’m coming here for some help. Sorry for the lengthy paragraph to all that read this far lol

-Brandon

 

At home
Cold engine
Remove the fan belt from the crank pulley
Start engine, Battery light will stay on that's OK
Go to engine bay and see if you can hear the noise, after the 5 seconds or so
Engine bay will be very quiet with no Fan, so should be able to pin point any noise

If no noise then the noise is coming from a pulley turned by fan belt

You can only run a cold engine for 60-90seconds without a water pump, so shut off engine before that, thats plenty long enough, lol, and you can REPEAT this test when ever engine is cold again

If no noise then spin the pulleys by hand, one will make a noise
Alternator bearing
Idler pulley
AC compressor clutch bearing are the more common noise makers

 

Thanks for your quick reply’s Ron, so I just took another listen to it on a cold start and it’s definitely an issue from the rear side of the engine, but I don’t think it’s coming from the engine at all. I took a very close listen to my right side cat and that’s where it sounds like it’s coming from to me, from what I described with it only happening at cold idle and then under load does that sound right to you? I also finally went out and bought a code reader because I have a check engine light on and it’s code p0420 and p0430 which have to do with the cats so in my mind i think that seals the deal but just wanna hear your opinion on it as im just starting to learn all this stuff for my self as it comes. Thanks

 

Engine off, tap in the CAT with a wooden stick or rubber mallet, if it rattles is breaking apart inside, so yes, failing CAT

 

So did some tapping with a 2x4 I had laying around and it sorta sounds like a little bit of rattle when I tap on the top of the cat, almost has like a hollow sound to it compared to my left side cat. I attached a short video of the sound you can hear it for about a second or 2 while I apply some load to the engine.