Subaru Outback Forums banner

1 - 8 of 8 Posts

·
Registered
06 OBW 2.5, 05 Forester, had 03 H6 OBW
Joined
·
5,935 Posts
Discussion Starter #1
OK, have what sounds like a front opinion (or front final driveshaft) bearing noise, pitch changes at about 4x road speed, but not much gear whine.

To me this means front pinion bearings, some bearing on the front pinion drive shaft, rear output bearing, or maybe the driveshaft carrier bearing.

Noise disappears with removing the load (just enough throttle to coast, or just coasting), amnd noise was not changed at all by inserting the FWD fuse (FWD light lit).

Other than trying to hear the noise with the car on stands, then inserting the FWD fuse and stopping the rear wheels, any other way to absolutely rule out the rear shaft bearing in the tailhousing or the carrier bearing?
 

·
Registered
2010 OBW limited 2.5 CVT
Joined
·
1,602 Posts
doing it on the stands might not work as there will be almost no load on the drivetrain (like your coasting test). It might work if things are far enough gone. If not, you still might be able to hear something with a length of hose or a stethoscope.
 

·
Registered
Joined
·
18,162 Posts
Does your H6 have VDC? If so, then the 4-speed tranny also has the VTD AWD transfer system. If the tranny has the VTD mechanism, the FWD fuse cannot not work to disconnect the torque to the rear drive train (thereby possibly reducing that as the source of the noise) because the VTD uses a mechanical center differential.

But if it has the "active" multi-plate transfer clutch, then the fuse should open the clutch, disabling rear drive, and it would appear that the noise is from the front drive train.\

Have you eliminated the rear transmission support bushing mentioned in another thread?

Can you get the car up on a proper hoist? If so, then insert the FWD fuse (subject to not having the VTD), have someone in the car, engine running, in gear, with just enough brakes applied to put drag on the front wheels. Then vary the brakes and/or throttle to cause the noise to appear, disappear, and then appear again. The other person underneath using a stethoscope, hose (as Wagondude noted) or just their ears, should be able to isolate the source quite reliably that way.
 

·
Registered
06 OBW 2.5, 05 Forester, had 03 H6 OBW
Joined
·
5,935 Posts
Discussion Starter #4
No VDC, and I think the rear drivetrain is reasonably excused.

Do you have a link to the mount thread?

I have checked the rear trans mount, it's not sagged much, and is not metal on metal.
I think the noise is now too loud to be just normal noise that is transmitted.

If I were not afraid the trans would grenade and strand me I would try replacing just the driveshaft and the trans mount, just to be sure.
 

·
Registered
Joined
·
18,162 Posts
Do you have a link to the mount thread?
http://www.subaruoutback.org/forums/66-problems-maintenance/51826-2003-4eat-bad-trans-mount.html

Without the VTD the fuse should eliminate the rear drive. But, again, having the car up on a lift could be far more conclusive. In fact, with the fuse in, the rear drive shouldn't turn, and if it does it should stop with just slight pressure on the drive shaft or wheels.

pitch changes at about 4x road speed,
I guess what you're saying is that the sound isn't likely from the front axles or wheel areas because of the relative pitch. (Pinion shaft turns about 4 times the axle speed.) But noise can carry in strange ways, and determining pitch changes from a distance could be problematic.

Generally I tend to lean toward the sound being from in the tranny/front differential, but, if there's any doubt, I'd prefer to have that pinned down more definitely before investing in replacing the whole thing. Listening for the noise at different points (e.g.rear of transmission, transmission case, bell housing/front differential, wheel hubs/steering knuckles) should do it.
 

·
Registered
06 OBW 2.5, 05 Forester, had 03 H6 OBW
Joined
·
5,935 Posts
Discussion Starter #6
Oh that thread, yeah, that was my thread. No metal on metal as far as I can determine.
I have dealt with wheel bearings and axles on this car, so I can rule those out as not the right kind of noise.






The 'pinion noise' vid is from last week, the others from today.

In person it's easy to tell the trans noise from the wheel bearing noise, on vid not as easy.
 

·
Premium Member
2001 VDC/SC One of a Kind
Joined
·
14,318 Posts
Since the noise generated doesn't change with gear change, that negates the transmission gearing and the torque converter. It does sound like a bearing in the front diff since it escalates with rotational speed.
 

·
Registered
06 OBW 2.5, 05 Forester, had 03 H6 OBW
Joined
·
5,935 Posts
Discussion Starter #8
Noise with rear wheels on the ground and not moving:


I think this is definitive, front pinion bearing.

I also confirmed even in 1, there is NO drive to the rear wheels until you step on the gas (whern I had all 4 off the ground, heh)
 
1 - 8 of 8 Posts
Top