(w/videos now!) Hunting down noises on acceleration from stop

[pachieh]

Interesting problem here… sometimes I am getting a weird rattling noise when leaving from a dead stop that sounds like marbles in a metal can for about 1-2 seconds and then it goes away. It doesn’t always happen and all my inspections under the car haven’t revealed anything yet. Exhaust system seems tight, oil pump chain was tightened on Sunday, nothing appears loose.

It may happen more in comfort mode than sport+ and I don’t think it’s wastegate rattle (stock DPs).

I do have a metallic rattle on cold starts that seems to come front the transmission area, but it does not sound like this main problem.

Thoughts?

[zeroping]

How many miles. Could be oil pump chain needs adjustment which has been discussed on the board a few times.

[pachieh]

Not that as I just adjusted it. 79k miles

[pachieh]

Bump… still running into this…

[jaaf]

have a vid?

[shimmy23]

front DS.

EDIT: sarcasm

[pachieh]

Hard to get a video as every time I try, it doesn't happen... Karma...

Not the front DS, just replaced it with an upgraded one.

[pachieh]

Videos are here! It is now reproducible on medium throttle and acceleration from a dead stop.

I've been under the car multiple times. Nothing is loose, transfer case has new fluid and calibration and a new front driveshaft. I'm thinking the center bearing on the driveshaft going to the rear as the culprit now...

[ferrarif1]

Did you figure this out? Mine is making a similar noise but not as loud. I was leaning toward a wheel bearing, but maybe you found something more.

After thinking this through more, I think my problem is a pinion bearing on the front differential. Does yours make a groan when decelerating or engine braking?

[pachieh]

Not yet. I have to get under the car and take the heat shields off that hide the driveshaft.

My guess is that since it happens under medium acceleration from a stop, there is a lot of flex in the center shaft support as it’s probably worn out.

I’m thinking that if this is the case, I’m going to do a full driveshaft service. New guibos on both ends, new center bearing, and a JXB center carrier support.