[clavalley]

I have a 2004 h6 with 154,000 miles on her and she runs great except for one thing. At speeds of 25mph plus there is a low rumble sound coming from under the front seats. It starts at about 25 mph and will increase and decrease with acceleration and deceleration. I checked the wheel bearings and they seem to be fine. I checked the cv axles with no leaks at any of the boots. I just changed the trans fluid and filter. I checked the rear drive axle and there is some play when you turn it clockwise and counter-clockwise, but not up and down. I bought the vehicle with 133,000 on her so i don't know the history of the vehicle. How common is it for rear drive axles to be replaced on gen 2's? I'm not saying that is it but just a hunch. I am not a mechanic but I did stay at a holiday inn express last night J/K. Anybody have an idea what it might be or what else I could check to find the problem? Any help or info would be much appreciated.

 

[CNY_Dave]

If it varies about the same as the speed you are going, it might be an axle.

If it seems to vary much more than a speed change you make, it could be the driveshaft to the rear differential, or the carrier bearing for the shaft, or even the rear diff pinion bearing.

 

[clavalley]

Hey CNY Dave,

I used to live in CNY but alas I have moved to the Adirondacks followed my bride)Anyway what other way could i check the axle besides cv boots leaking without taking it off? or should i just take the culprit off. I am guessing the guy who had the car changed them because both axle nuts are bronze in color and seem new, just thinking aloud some ideas. I had a chevy pick-up that had a pinion bearing go and they sound similar but the trucks was much more noticable. This rumble is not very loud, but I notice it because I am pretty anal when it comes to odd noises coming from my car. the other thing this is my first subaru so maybe it is normal. Does your '03 ****** have any noises like this? Are the carrier bearing, pinion bearing, or u-joints serviceable? I have heard they are not and if you need a drive shaaft to contact wholesale import parts to get one. I am going to my buddies and put it on a lift and see from underneath while wheels are running where noise may be coming from. thanks again.
Chad

 

[CNY_Dave]

I don't think I have a rumble, and CV joints probably would not rumble.

My rearmost U-joint has a little slop but no noise so far, and yes, you have to get a new shaft, and have to do so to get a new carrier bearing. Pinion bearings are serviceable.

If you have VDC the prop shaft wears faster than on the non-VDC automatics.

Another thing it could be is the rubber in the rear transmission mounts may have 'sagged out', or the same may have happened with the rubber bushings that mount the rear diff.

Or it could just be the exhaust pipe touching the body.

 

[clavalley]

okay, just got back and there doesn't seem to be anything noticeable on the lift with car running and in gear forward and reverse with acceleration and deceleration, just a loose heat shield and i fixed that. i never thought to check the rubber bushings that mount the rear differential or rear transmission mounts if that was it that would be a cheap fix. I have non-VDC mine is a 35th anniversary edition. The rumble definetely is associated with speed of car. Maybe I'll try the fuse trick disabling AWD and leaving in front wheel drive and see if that changes anything. I assume it is normal when turning to hear the clutches working in the rear differential? I don't think I have torque bind the car turns at idle right and left turns. i'll check the rear transmission mounts and rubber bushings on the rear differential.... stay tuned

 

[CNY_Dave]

Don't know what you mean by hearing the rear diff clutches- should not make any noise, you'd feel a little binding on tight slow turns if the rear diff was locked.

If you were to describe this more as a 'humming' I'd say wheel bearing. I have a noisy rear one and I could say it's coming from where you describe.

If you are hearing a clicking on tight turns, that's probably an axle or maybe a loose wheel bearing shifting position.

 

[clavalley]

I am with you on the wheel bearing. My friend with the lift is gonna help me do a process of elimination with each wheel bearing front and back. rubber mounts for rear trans were okay and bushings on rear differential are okay as well. will repost when i find out.

 

[clavalley]

front passenger side wheel bearing.

 

[CNY_Dave]

The wheel bearings can be tricky, as far as figuring out which one it is.

Spinning the wheel with a metal rod held against the strut and tucked into my ear with my thumb over the end was the only way I ID'ed my bad front one.

It even got louder/softer while turning, but the reverse of the usual...

 

[CNY_Dave]

Heh, we posted at the same time. Mine was front drivers side, either from my bombing freeway ramps or from an accident before i bought the car (which I knew about pre-purchase)