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Center diff bearings replaced, but "jet" noise remains...


Scruit

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My car recently started making a noise that sounded like a supercharger or jet engine. Dependent on road speed only, and starts at about 40mph and gets louder with speed. Sound came from all over, can't directionalize.

 

First thing I did was check the front wheel bearings. Passenger side was clicking a little when I tugged on the wheel, and there was a roughness in the bearing on rotation. I replaced the wheel bearing.

 

The noise changed, so the wheel bearing was making *some* noise, but the main "jet engine" sound remained.

 

 

I put my chassis ears on the carrier bearing, center diff cover, extension housing and right next to the front diff, and found the center diff was making some horrible noises.

 

I replaced the 4 bearings inside the extension housing - the output shaft to the rear driveshaft had a ton of lateral play, and now it's solid. I didn't replace the center diff itself.

 

Got it all put back together, and the noise is still there.

 

The carrier bearing is quiet.

 

So, other than the center diff bearings, what else could be the source of this noise?

 

My thoughts:

 

- Front diff or driveshafts? (chassis ears didn't pick up any noise at the front driveshaft)

- New bearings are bad? (All installed using proper tools and a shop press)

- The center diff itself is bad (can't think of how it would make the noise though)

- Transmission bearing on the output side, before the center diff?, requiring me to crack the trans open.

 

 

 

I'm not putting a transmission in this car.

 

The $500 that the center bearing would cost would be an acceptable fix, but I don't want to speculatively replace the diff...

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Yea, these things do make some noise. My wagon's tranny is loud under load in the lower gears, has the whine of a supercharger. These things do have straight cut gears in 1st and 2nd.

 

I also have the decel noise when I lift off the throttle and the car is under 60mph, above that the tranny's quiet. I have learned to push in the clutch and coast in neutral in those cases. Mainly it's rolling down hill to stop sign.

 

Most other times I'm on the gas.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

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The bearings quietened down after the 1 mile test drive, so I suspect I didn't pre-oil them enough and they took a minute to get lubed up.

 

I can hear the other transmission noises... yeah, these transmissions are very... communicative. :-)

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