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'03 Outback H6-3.0 Black Granite Pearl, base model with cold weather package and cloth seats.
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1,094 Posts
Discussion Starter · #1 · (Edited)
Just had to replace the idler pulley (bearing). This is the second idler pulley (bearing) replacement in the life of the vehicle.

Just for grins, i looked back in my detailed records to see just how often these bearings are failing (tensioner and idlers both).

Turns out both the tensioner and idler pulleys have been replaced twice in the 337k+ mile history of this vehicle.

idler:
first replacement: ~189k miles
second replacement: ~337k miles (~148k miles on this one)

tensioner:
first replacement: ~140k miles
second replacement: ~311k miles (~170k miles on this one)

This seems relatively consistent between pulleys. All replacements prior to this one have been done with replacement Subaru Idler or Tensioner assemblies, not just pulley bearing replacements.
Based on reading information on this board, I decided to buy a bearing and replace it myself in a used pulley.

Some observations:
There are two pulleys you may come across. One has a lip at the back edge of the belt drive surface. The other doesn't. They seem interchangeable and the belts ride in the same/proper location with either.

Replacing the idler pulley is a piece of cake. 15-30 mins tops.
Pull the intake snorkel to get working room. Use 14 mm combination wrench to unload tensioner and remove serpentine belt. Start with the wrench on the tensioner pulley bolt as far to the left as the hose will let you. You will need the full throw on the wrench to sufficiently unload the tensioner to remove the belt. No need to remove upper radiator hose.
Unscrew the old one and replace with the new one. No hidden nuts to worry about losing. Ensure the washer under the bolt head is oriented properly to prevent it from freezing the pulley rotation. Torque to 25 ft-lbs.

Replacing the tensioner assembly is more involved, and requires also removing the upper coolant hose, from a working room standpoint.
Replacing just the pulley should be slightly easier than a complete assembly replacement, but you need to ensure you don't lose the semi-captive nut on the back of the tensioner arm where the pulley is mounted.
Tensioner assembly replacement should be 45 minutes to 1 hour. It's difficult to see where the bolts go, and you'll spend some time fishing around in there, at least the first time you to it.
Pulley only replacement should be 30-45 minutes while you fiddle around ensuring you don't lose the nut, or finding it if you do.
Re-install belt and snorkel and you're done.

On an old tensioner assembly, the bolt can be pretty tight. Be prepared for a bit of work to get it off. May require removing the assembly and removing the bolt on the bench instead of in place on the engine.

Old bearings come out with a couple good whacks with a hammer on a large diameter socket.
Bearing installation is best done on a press with a suitably sized socket or slug of metal to ensure only the outer race receives seating pressure.
Seems like no need for bearing locker, as these go in pretty tight. I couldn't even find bearing locker compound when I looked for it, and no one had heard of needing it.

Regards,
 

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OBW H6 VDC, Tribeca, XT6
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12,386 Posts
it's odd how they fail at all sorts of mileages, you've got some good longevity out of yours.

i don't remove the coolant hose to replace them but I totally understand why you'd want to.
 

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2004 Subaru OBW L.L. Bean H6. 2003 Subaru OBW L.L. Bean Former 2001 Subaru OBW VDC owner.
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1,316 Posts
it's odd how they fail at all sorts of mileages, you've got some good longevity out of yours.

i don't remove the coolant hose to replace them but I totally understand why you'd want to.
what mileages have you seen tensioner pulley's fail at?
 

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2009 3.0R Outback
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1,032 Posts
Replaced just the bearings on my '09 H6 at 152k with Timken 203FF. They have around 38k on them now.

I think at least the idler pulley was replaced by the PO at some point. It doesn't have a lip on it and the bolt washer was all bent up like the OEM idler/bearing grenaded.
 
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