Metallic Noise in Drive and Reverse at idle coming from front end

Sounds like front differential but not sure?? Any advice 1996 3.4l 285k

 

Drain diff fluid and look for chunks?

 

I'd look at cv joints and make sure they're not blown. Then the driveline and then drain diff.

 

You going to have to dig a little deeper into the situation. When in doubt lift the front end and start moving things until you can replicate the grinding sound.

 

I've drained the diff fluid a month ago, found some metallic on plug and some chunks but not a lot. Thought it could be u joints but not if it is occurring during idle. I have replaced one cv axle on passenger side but drivers side seems fine. I put camera under truck. sound is made when at idle, so cv axles aren't moving and u joints aren't either??

 

Noise only occurs at idle? Maybe a motor mount or tranny mount?

 

Yes, but only in Reverse, Drive, 1,2 but not in Neutral. I made a video of the noise but noticed the file is too big to upload. I'll try linking to youtube soon. I'm wondering if it's the spider gears in the differential because noise sounds metallic and like its going to lock up.

 

Something on the exhaust, lose or cracked??

 

I don't think so, but i'll check it out in the morning. I'll let you know how it goes.

 

Sounds like a engine related noise under light load. Check all your heat shields and everything driven by the belts. I know 3.4s are supposed to be amazing but check your oil and drain plug for metal if you determine it's inside the engine. Could also be cat rattle. And like @cruiserguy said, check your mounts. Idk how the crank pulley is built, but if it's a 2 piece dampener, maybe the rubbers worn out? Go to harbor freight or a parts store and pick up a mechanics stethoscope. Be careful, they can hurt your ears but use it to find the noise. Or if you have a long screwdriver or pry bar, put it up against whatever you think the noise is coming from and put your ear on the other end. The sound will resonate. It's a poor man stethoscope.

 

Definitely could be an engine problem, I've been seeing oil on the bottom end all over. Sometimes splattered on around areas by the starter, oil pan etc. Thanks for the advice!! I let you know how it goes.

 

What was the result? I am having same noise while only at idle in drive and slightly worse sounding in reverse.
No noise in park or neutral. Doesn't happen at cold start but only after hot and driven for a few miles.

 

Broken catalyst rattling around in one of the cats? That can make a racket at certain RPM and it can be temperature dependent.

 

Makes sense, I’m not passing smog (high NOX @ 15mph, yay California) and am being told to replace the cat. Going by my exhaust guy today and will update with solution.