2013 Limited AWD 3.5L Rattle while in gear at low RPM

[ArtdW]

Hello:

 

I have the above described vehicle at 87,000 miles. I get an intermittent rattle/knock only while in gear (forward or reverse) and at lower rpm, from about 900rpm to 1500. Above and below that RPM range it goes away.

It shifts and drives normally. I have no check engine nor did we get any codes when my mechanic plugged it into his machine. This just started a week ago or so. To this point we have had no issues with the vehicle.

We get the noise while driving and we are also able to duplicate it by holding the brake and raising rpm slightly to the 900-1500 range. It never does it in park or neutral. 

Oil is fine, Trans was recently serviced, flushed twice and refilled about 3,000 miles ago. All levels are good and no leaks. PTU has not been serviced to my knowledge as we purchased it used early last summer.

Seems to be more prevalent after first start and cool but does occur when engine is at full temp as well.

I have had it on a lift and we used a stethoscope to try to find it. Unfortunately, it was very intermittent while it was up in the air and we had a hard time duplicating the noise long enough to pinpoint the location. However, it seemed to come from the back of the engine and not the transmission. Again, we could only get it to make the noise while holding the brake and in gear and getting the rpms in that range while on the lift.

I am going to give it back to my mechanic and he will make another attempt after a cool start. We went ahead and did an oil fast flush with Mac's 5830, and changed oil just to throw a dart at it and no change.

See attached video please. Any thoughts on what to check would be appreciated.

Thanks,