Knocking noise in front

[14D]

So I've had an intermittent "knocking" type noise coming from somewhere in front for the last couple years and 15-20k miles.  It started after driving on a torn CV boot for a bit and sounded like it was coming from that side (driver's).  I had a trusted mechanic reboot it (last time I paid anyone to work on my car) and he said everything was fine internally and of course the car wouldn't reproduce the noise for them.  It stayed very intermittent until the last 7-8k and in the last couple thousand or so has become a pretty much constant noise.  

 

Originally turning left reproduced the noise more often but lately turning either way will produce it, if its not making it already.  It is also sensitive to throttle input and it only makes the noise when I'm on the throttle in gear (ie when I'm not coasting or have the throttle shut in gear).  It sounds like a bad CV joint but more of a knock than a clicking sound.  It is consistent with tire speed, not engine rpms.  I recently replaced the wheel bearings, ball joints, ad tie rod ends in the front as well as rebooting/inspecting the other axle.  Some were pretty bad so I was hoping this would fix the noise.  Struts and mounts are in decent shape,  my control arm bushings are pretty shot but I don't really see that causing this noise and the really bad one is on the passenger side and while the noise could be coming from anywhere it sounds more to the drivers side or center of the car. 

 

At this point I'm thinking transmission or differential and will be draining my gear oil to check the drain plug later this week.  So my question is if the trans/diff is bad should I replace it?  There's no way I can afford a decent car right now but with all the crap I still have to fix (suspension bushings all around, total timing belt job, and new tires soon, plus a clutch if I have the trans out) not to mention the rough body (I don't mind it looking like crap as long as it runs and drives fine but at the same time it doesn't make sense to spend more than something cheap but decent would cost) so it might not be worth it.  I'm torn what to do as I've grown to love this car and don't mind doing the work.  93 legacy wagon, fwd, 5spd, 260k.  

 

Also I'm not positive but I think one time a few years ago I drove a few hundred miles with the mini spare on the front, with 200 of it being at freeway speeds.  I can't remember for sure if that flat was on the front or not, but I didn't know it could damage anything at the time and wasn't missing my vacation, lol.  Still not sure if this is as detrimental to FWD cars as the AWD ones.  I'll certainly heed the warnings in the owners manual/on the tire next time though. Just remembered I have changed the gear oil since this started (probably 12k ago) and all was normal then (just a small collection of fine shavings).  However the noise has certainly gotten worse since then, mostly in how frequent it is but also has become louder and more intense, maybe a 30% increase, mostly in the last couple thousand miles.  My shift shaft seal has started leaking in the last 10k but not enough to where I've had to add fluid.  Thats about all I can think of that might be helpful.

 

Sorry for the long winded post but I know how hard it can be to describe these problems let alone attempt to diagnose them over the internet.  Thanks in advance for the replies.

Edited September 10, 2013 by 14D

[1 Lucky Texan]

well, as for just working with some WAGs, I'll offer a couple;

 

double check the 'transverse link' bushing. Sometimes called the front lower control arm rear bushing.

 

as a wild experiment, you could swap axles left to right in the front. If the inner tripod joint is making the noise, it will make it on the other side now - or possibly stop with almost new wear surfaces in play (cause, only reverse would previously be wearing the axle.)

[14D]

well, as for just working with some WAGs, I'll offer a couple;

 

double check the 'transverse link' bushing. Sometimes called the front lower control arm rear bushing.

 

as a wild experiment, you could swap axles left to right in the front. If the inner tripod joint is making the noise, it will make it on the other side now - or possibly stop with almost new wear surfaces in play (cause, only reverse would previously be wearing the axle.)

 

 

My transverse link bushings are shot. the right side is a lot worse than the left though.  Could this be causing the noise?  It sounds more like something that is rotating, but who knows.  Sounds can be very deceiving and difficult to track down.  And that would make sense that the noise was worse/happened more frequently when turning left.  Last time I looked into it my best (and possibly only) option was getting some used ones off carparts.com or a yard.  My steering wheel has a shake/shimmy to it but it seems to be slower than the noise.  this has also gotten worse with the noise in recent weeks.  Unfortunately I'm dead broke and jobless at the moment so any repairs will have to wait a bit.

[idosubaru]

Which boot was busted/replaced - inner or outer?

Sounds very telling that the axle needs addressed, increase that sentiment if it's an aftermarket axle:

 

  It started after driving on a torn CV boot

The descriptions...getting worse over time, wheel speed, under load (throttle related) all sound very axle suspicious.

I would hold off on the trans as that money may be better spent on axle work than trans fluid.

 

Cost conscious options:

 

1.  swap the axles side to side and see if the noise moves or like LT said it may load it differently and go away.

2.  remove both axles and swap the guts...i forget which way and if it matters but I've heard of people doing that and they say the parts wear differently when installed on the other side.  I haven't done it or taken them apart and compared side to side to see if that makes any sense or is any different from option #1.

3.  buy a used Subaru axle - i routinely buy them for $25, could probably find one for $15.  www.car-parts.com search by zipcode

 

#3 is what i always do as a rule since aftermarket axles are low percentage and problematic.

 

running the spare should not have hurt your transmission at all, it's just an open diff, only one wheel is driven at a time, the other can do whatever it wants.

[1 Lucky Texan]

that LCA rear bushing 'transverse link' is THE single most heavily loaded spot that transfers tractive and braking forces to the body of the car. You may wear-out tires faster too. To do it right is a little pricey. Do it cheaply (with poly bushings) and you have quite a bit more 'fiddly' labor and will also have a lot more harshness. If you put the car on jackstands and push pull the rear of the lca, does it hit the inside of the mount? if the fluid is leaked out, they still sorta work OK, but if rubber is gone - I could DEFINITELY understand them making noise.

 

agree with GG on axles. And often, people go weeks/months with them making noise - but they will fail eventually leaving you stranded. Outer joints usually 'click' though - dunno about knocking.

 

as for any other ideas to check; broken springs can be hard to spot, double check anti-sway bar endlinks and mounts (and for breakage), I guess struts/strut mounts could be a source???

Edited September 10, 2013 by 1 Lucky Texan

[14D]

I believe the axles are subaru re-manufactured ones.  I had a hard time finding boots for it and had to have a parts guy measure the old ones and match the dimensions up.  I remember reading somewhere on here about old brat axles being used for subaru remans or something, idk.  My inner DOJ's are huge compared to normal ones though.  I only drove on the torn boot on the driver side for a few hundred miles and still had plenty of grease left in it when I had it rebuilt.  When I had the hubs off to replace the wheel bearings earlier this year I could detect no play in the joints of the driver side axle.  I rebuilt the pass side at the same time as the rubber was starting to crack and it appeared and felt fine as well.  At this point I'm thinking it's the rear control arm bushing the more i think about it.  If the noise persists after replacing those I'll try swapping axles.

 

I replaced inner and outer tie rods in april as well as the ball joints (while doing the wheel bearings).  My rack and pinion boots had been torn for a while and the rubber was cracked on the outer tie rod ends as well.  The passenger side ball joint and inner tie rod were shot, I could get close to a 1/2" of play out of the wheel between the two.  Definitely should have checked it all out sooner, but for a while was just planning on replacing the car but now can't afford anything else or even want a newer one if I can keep this one on the road. 

 

I could get at least a quarter inch of play out of the control arm just yanking on it with the suspension unloaded from the rear bushing, so its definitely toast.  Driving on the blown out ball joint and inner tie rod end and my tendency to drive too fast on dirt roads surely accelerated its wear.  Replacing these sounds easier than swapping axles at this point, if I can find some.  IIRC there isn'n't a part number for the whole assembly that unbolts?  I'm thinking my best and cheapest option is find some from a yard off something newer with lower miles, maybe from somewhere other than the southwest which is very hard on rubber.

 

I could detect no signs of fluid around the bushing so its likely all gone (if the 93's had fluid filled ones?)  The LCA wasn't hitting the inside of the mount in april, but it might be by now.

 

and good to know about the diff and spare.  That's what I'd thought originally but wasn't sure anymore

Edited September 10, 2013 by 14D

[1 Lucky Texan]

there are numbers for the entire unit.

 

there's a lef and a right side. The torque values are huge and, with stuff just 'snug', you are gonna want to drop the car and bounce it, crawl under with it on the ground and torque it to full-tight. Then , drive it around for a few days, re-torque again. Wouldn't hurt have it aligned - or wait till you get new tires and align it.

 

while I went with poly, there's a DIY around here somewhere for the lca. Yeah, you might look here for some idea of what's involved; http://www.subaruoutback.org/forums/99-do-yourself-illustrated-guides/48910-lower-control-arm-rear-bushing-transverse-link-replaced-prothane-03-outback.html

Edited September 10, 2013 by 1 Lucky Texan

[14D]

Poly bushing might be the ticket, they gotta be quieter than it is now.  Thanks for the link, I think I've actually read it before when I first discovered the bushing was bad while researching it.  Would it be worth installing a grease zerk on the bushing mount for the poly bushing, or does it even require regreasing?  Whats the life expectancy like on those?

[1 Lucky Texan]

I don't have great answers to your questions. No squeaking yet on ours. I don't think a zerk could get new grease where it needs to go. The grease they furnished was very thick and I used it all. YMMV

 

others here I'm sure have more experience with poly bushings.

[Fairtax4me]

I've had my fair share of fun with worn out transverse arm bushings.

Yes they will clunk and knock when they go bad. If you can move it AT ALL by hand, don't you think 3,000 lbs of car is going to have a LOT more push and shove when going around a corner or braking/accelerating hard?

 

They are fairly easy to replace though. They just cost about $70 a piece from the dealer.

Poly is a cheaper alternative, but they will start to squeak after a few months of heavy use on dirt roads. You may have to take them apart to clean and regrease them once in a while to prevent wear and noise.

[1 Lucky Texan]

When mine start having a problem, I'm buying stockers to go back on.

[14D]

I've had my fair share of fun with worn out transverse arm bushings.

Yes they will clunk and knock when they go bad. If you can move it AT ALL by hand, don't you think 3,000 lbs of car is going to have a LOT more push and shove when going around a corner or braking/accelerating hard?

 

They are fairly easy to replace though. They just cost about $70 a piece from the dealer.

Poly is a cheaper alternative, but they will start to squeak after a few months of heavy use on dirt roads. You may have to take them apart to clean and regrease them once in a while to prevent wear and noise.

Thats what I figured when I could move it so easily, just didn't expect it to make a noise like that. $70 a piece isn't bad, and stockers sound much better than the poly.  

 

Thanks for all the replies, sometimes bouncing ideas around is the best way to solve problems.  I'll make sure and post up if this solves it or not when I get it done.

[Fairtax4me]

Just checked on these (reading this thread reminded me I have to replace one on my project car), online dealers are charging $60 each. List price is $83.

[1 Lucky Texan]

Just checked on these (reading this thread reminded me I have to replace one on my project car), online dealers are charging $60 each. List price is $83.

$60 is much less than what I was finding before my project. maybe 03 H6 is higher?

 

anyway - unless you have some performance goal in mind, or absolutely MUST save the last dollar, get the OEM units. Even worth borrowing $$ from a parent or - gulp - ex-wife.

[Fairtax4me]

Outback bushings are $80. (95-09)

Outback bushings have a different offset because of the spacer blocks between the cross member and frame. Rear of the TVA has to sit lower as well. IIRC also moved the center out a bit to give Outback more positive caster.