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2003 Outback (H6) Clunk noise and humming noise question


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#1 dbullen

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Posted 23 January 2012 - 11:19 AM

I have a 2003 Outback with H6 here's what's happening.

If I accelerate quick off the start, I hear a loud clunk noise that sounds like it's come from dead center of the car below the center console/shifter area. You hear the clunk only when you give it a bit harder then normal from a start. Also hear the exact same clunk noise if you brake hard (You hear the noise 1/2 second before car comes to complete stop).

Also hearing a humming noise, that is really noticable at 30-35 MPH and above or below that speed you still hear it just not as noticable.

Also have a slight vibration in wheel only when your on the throttle either first starting off (accelerating from a stop) or going up a hill (Whenever there is more load on the vehicle). All new tires/ wheels have been tripple checked for balance. No difference between summer/winter tires rims, so I know it's not a wheel tire issue.

I'm having my subaru guy (master tech) look at the issue this weekend however he's tried to figure out the clunk last time I was up and though it might be a drive shaft issue, he dropped the back part of the drive shaft and it looked fine but didn't have time to look at the front part. Just wanted to see if anyone has had any similar issues and what the problem was.

#2 johnceggleston

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Posted 23 January 2012 - 05:53 PM

i just bought an '01 outback VDC w/ H6, 157K miles and a DEAD trans. i replaced the trans and found a bad rear trans mount in the process. have your guy check it out. pick up on the rear of the trans. there is a rubber cushion in between 2 metal plates. i don't know how the plates are attached to the cushion, mine was completely loose, one plate not attached to the cushion.

~$67 from the dealer, less wholesale or online.

humming could be the power steering pump, that's on my list.

#3 dbullen

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Posted 23 January 2012 - 07:11 PM

i just bought an '01 outback VDC w/ H6, 157K miles and a DEAD trans. i replaced the trans and found a bad rear trans mount in the process. have your guy check it out. pick up on the rear of the trans. there is a rubber cushion in between 2 metal plates. i don't know how the plates are attached to the cushion, mine was completely loose, one plate not attached to the cushion.

~$67 from the dealer, less wholesale or online.

humming could be the power steering pump, that's on my list.


Thanks for the reply, My transmission was rebuilt a few years ago as well, mounts were okay then, though could be worn now, I will have him double check that.

Humm is only when you're in drive and at 50-60 KM/hr, sounds like it's coming from drive shaft, but thinking maybe wheel bearing, or maybe something else who knows.

#4 CNY_Dave

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Posted 24 January 2012 - 09:18 AM

Does the hum seem to increase at the same rate as wheel/vehicle-speed, or at about 4x the rate of wheel speed increase?

The driveshaft spins 4x as fast as the wheels so the pitch changes radically with vehicle speeds, wheel bearings not so much.

A bad U-joint won't hum, but the center carrier bearing can.

If it's a VDC car the driveshaft wears quicker as it always sees at least 55% of the power.


Dave

#5 dbullen

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Posted 24 January 2012 - 10:11 PM

Does the hum seem to increase at the same rate as wheel/vehicle-speed, or at about 4x the rate of wheel speed increase?

The driveshaft spins 4x as fast as the wheels so the pitch changes radically with vehicle speeds, wheel bearings not so much.

A bad U-joint won't hum, but the center carrier bearing can.

If it's a VDC car the driveshaft wears quicker as it always sees at least 55% of the power.


Dave


It's an H6 LL bean, so don't believe VDC. The humm starts at 30 mph or so and is gone by 35-40 mph. Or atleast faint enough you can't hear it over the engine/wind noise (It is loudest around 33/34 MPH). I've noticed it for probably 6 months, but in the last few weeks has gotten much lounder.

#6 CNY_Dave

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Posted 25 January 2012 - 12:21 PM

If it just starts to hum as you speed up, stays that same tone/pitch, then fades away it's probably a sympathetic vibration.

Wheel bearings and carrier bearings and bad diffs change the tone/pitch with vehicle speed.

Dave

#7 dbullen

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Posted 02 February 2012 - 06:05 PM

Appears to be the carrier bearings in the front differential that is causing the noise, looks like they will have to be replaced.

#8 CNY_Dave

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Posted 03 February 2012 - 09:04 AM

Hmmm, did the front diff lose some fluid?

#9 dbullen

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Posted 03 February 2012 - 09:27 AM

Hmmm, did the front diff lose some fluid?


Nope it's full, and carrier bearings were replaced approx 100,000 miles ago when I had transmission rebuilt.

#10 ivans imports

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Posted 03 February 2012 - 12:28 PM

i fix alot of center clutch packs that are still ok but not tight enuff if its loose when it trys to go awd it clunks or shudders the clutch pac has to be set verry tight almost 0 clerance the h6 has very good tourqe so it can rip out a center diff clutch easyaly

#11 ivans imports

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Posted 03 February 2012 - 12:33 PM

ps is a very hard trans to rebiuld diff is very hard to set if its been messed with throw it away and start with one thats never been touched takes me 4 hrs to r@r the front diff belive its 4.44 [dont mess with factory settings ]

#12 dbullen

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Posted 03 February 2012 - 01:07 PM

ps is a very hard trans to rebiuld diff is very hard to set if its been messed with throw it away and start with one thats never been touched takes me 4 hrs to r@r the front diff belive its 4.44 [dont mess with factory settings ]


Was rebuilt by a friend of mine who is a master subaru tech at one of the dealers. Has worked great the last 100,000 miles until now.

#13 dbullen

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Posted 03 February 2012 - 01:13 PM

i fix alot of center clutch packs that are still ok but not tight enuff if its loose when it trys to go awd it clunks or shudders the clutch pac has to be set verry tight almost 0 clerance the h6 has very good tourqe so it can rip out a center diff clutch easyaly


But I do get a shutter/vibration when under load/ up hill, accelerating from a stop.




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