2000 Legacy L Wagon - Mysterious Vibrations After Impact on Freeway

[dirty_mech]

This is a strange one that I've been trying to fix it for over a month.

4th of July I'm driving home at night on an empty freeway after a long trip and hit something in the dark.  It felt like a 4x4 piece of lumber.  Sent the front end of my car flying for a hot second.  Pulled over a bit later and couldn't find any damage.  Didn't notice any driveability issues so I made a note to get my alignment done later and went on my way.  About 30 miles down the road I start to get a  strong vibration through the stick shift that would get worse with acceleration and engine load.  No vibration when coasting regardless of speed, and no noticeable vibration at lower speeds and engine loads.  Eventually it would get so bad the whole car would shake. Turning the car off and letting it sit helped reduce the vibrating for a time.  I eventually limped it home, mostly by driving around 60 in 4th gear to minimize the vibration. 

At this point the thing I hit on the road is so far out of my mind that it didn't even occur to me that it was related.  The vibration was also behaving like an engine mechanical or performance issue.  So I end up changing my oil, air filter, spark plugs, wires, ignition coil, and adjusting my valve clearances.  Engine is running better but vibration still there.  Get my front wheels rebalanced and learn that impact must've knocked the weights off of both front wheels.  Finally notice the vibration issue at a lower speed, this time after hitting the gas hard when taking off from a parking spot, which makes me suspect a powertrain and/or suspension issue.  Had Les Schwab check the underbody and they found no issues.  Checked it myself today; saw some nice scrapes on the underbody shell but no real mechanical damage that would explain the weird vibration.

Someone suggested a dropped valve but that seems to always correlate with misfiring, which I am not experiencing.  Numbchux suggested in the original thread that it might be low oil pressure.  I'm going to check for that but am a bit skeptical given the strange symptoms and proximity to the freeway impact.  I'm considering that a drivetrain or suspension component might be damaged in a way that's not noticeable.  If you've got any guess as to what could be causing these symptoms, please share!

Original thread:

 

 

 

[brus brother]

Stomping on gas and taking off from a parking spot sounds like drive shaft, U joint.

Any play?

Subies are robust but not meant for Dukes of Hazzard jumps.

[heartless]

engine or tranny mount, maybe?

would not necessarily be noticeable just by looking at them... but could cause issues under load

[dirty_mech]

brus brother - I just checked the U-joints on the driveshaft as best as I could without removing anything, which wasn't great.  The back one feels fine, what I can see of the front one looks OK, and I wasn't able to see the center portion of the shaft due to the exhaust line heat shield. 

I will remove the exhaust and heat shield if people think my symptoms are spot-on enough to check, but I'm starting to get tired of chasing my tail here.  I might just give up and have a mechanic take a crack at it this week. 

Heartless - I hope so.  I've spent a lot of time under that Subaru and looked for such things but didn't find them.  Still you're right, a ratchet trying to snug down all the bolts would be a better way to check.  I hope it's something like that or a driveshaft u-joint.  I may check for both those issues in the near future if I find the time.

I just got done checking the oil pressure as Numbchux suggested.  Just over 25 idling, and just over 75 at 5000 RPM.  Service info reportedly indicates 14+ PSI at idle and 43+ PSI at 5000 RPM, so it would seem I am fine with regard to oil pressure.  Bloody oil light didn't come one even with the sending unit disconnected; perhaps I've got a bad one?  Photos:

 

 

But thank you for the idea.  I wonder if this still an oil issue possibly however; I've been doing 10k oil change intervals with Wix XP filters and full synthetic for the past 50k miles or so, which is probably a bad idea for one reason or another given how particular these engines tend to be.

If I get to checking the driveshaft and underbody mounting bolts - or taking it to a mechanic - I'll let you all know.  Let me know if there's any other tests or things I can check.

A couple photos from under my car:

Big scrape mark on rear left section of underbody, possibily from the freeway impact.

This is my front left halfshaft.  The smaller CV boot connection has come a little loose and both connections are leaking a tiny bit of grease.  Other halfshaft CV boots are snug and no leaks.  Same side of car as underbody scrape; perhaps the thing I hit was more on the left side of the car?  Makes me wonder if these CV axles can become internally damaged from an impact without significant leaking.  Still hard to say how this would make my symptoms worse after an extended drive.  Quite an annoying mystery...

[Daskuppler]

It kinda sounds.like bad CV joints. The inners won't click on tightt turns like the outters do, but they will cause a bad vibration under load. If it is slowly leaking grease, it may be bad. They don't usually get worse as things warm up though.

Parts store CV axles suck though so this can be an expensive repair with Subaru parts. 

Edited August 8, 2022 by Daskuppler

[ferp420]

check your carier bearing that would be affected by heat and load it could be torn half way through but still wouldent be obviose at a glance and its the lowest point of the drive train vary easy to snag or smack it on something

a simple push pull test should tell you if theres a problem down there pretty quick if it moves more than a 1/4 of a inch in any direction thats probably the problem 

[lmdew]

Pull a used Subaru Halfshaft from the yard.  Clean, grease and reboot if needed.  Heck, just to see if the symptoms go away, install as is.  Rebuild down the road if necessary.

I take my 3/4" 4' long snapon ratchet with 6 point socket to the yard.  No nut has ever beaten that tool.  If the outter spline does not move freely once the nut is off move on to another Subaru.  Make sure when you put it in the innner rollpin is propperly aligned.  If it's 180 out, you can start it but it will jam before you get it all the way in and you will be hard to get it back out!

[el_freddo]

Jack up your front wheels and check for bearing play or noise. Also rotate wheel left then right and vice vests to load up CV joints and listen for any creaking or odd sensations as you do this. 

Do this on the rear wheels too. 

Cheers 

Bennie

[dirty_mech]

9 hours ago, Daskuppler said:

It kinda sounds.like bad CV joints. The inners won't click on tight turns like the outers do, but they will cause a bad vibration under load. If it is slowly leaking grease, it may be bad. They don't usually get worse as things warm up though.

Parts store CV axles suck though so this can be an expensive repair with Subaru parts. 

Well damn, that sounds like what I'm experiencing.  I also have an annoying click on tight turns, especially in the morning when I first start driving.  Even before the freeway impact.  The Les Schwab guys first thought CV axles when I described the issues to them, but they didn't see anything physically wrong with the shafts.  Perhaps because they are the aftermarket garbage you all are warning me about.

Sounds like plenty reason to try swapping out the axles.  I first replaced them 7 years ago.  Just looked them up and they were A1 Cardone 66-7259.  Lasted 7 years and 60k miles so far, but I suspect that unplanned Dukes of Hazard jump I took messed up at least one of them.  At the very least it's causing that clicking noise on turns so I will replace them.

I hear you guys on the OEM shafts.  I very nearly bought some replacement Cardones this morning but saw this thread in addition to your comments:

https://www.subaruoutback.org/threads/cardone-heavy-duty-axles.497231/

It really pains me to go to Pick n Pull to rip off 20+ year old parts and put them on my car, but I guess that's what I'm doing.  I'll take Imdew's advice Hopefully the employees will let me go through the gate with a jack stand so I can hold the wheel in place using the lug to break the hub nut, or I'm going to have a real fun time trying to get them off.  Forget why I replaced the original ones, maybe it was a click or just torn boots.  What a mess...

I am going to try to avoid any OEM axles with torn boots.  Hopefully I'll see a Fuji or Subaru symbol on the axles so they are easy to identify.

Oh and here's a morsel from that thread I posted above:

Sure sounds like my problem, doesn't it?  I'll let you all know what it drives like with some OEM shafts on it, and if Daskupller guessed it right. 

Will hit up Pick n Pull soon.  If anyone has had a recommendation regarding what boots to use for rebuilds, I'm glad to take it.  I may replace them in advance just to save on future maintenance down the road.

Edited August 8, 2022 by dirty_mech

[Daskuppler]

30 minutes ago, dirty_mech said:

Well damn, that sounds like what I'm experiencing.  I also have an annoying click on tight turns, especially in the morning when I first start driving.  Even before the freeway impact.  The Les Schwab guys first thought CV axles when I described the issues to them, but they didn't see anything physically wrong with the shafts.  Perhaps because they are the aftermarket garbage you all are warning me about.

Sounds like plenty reason to try swapping out the axles.  I first replaced them 7 years ago.  Just looked them up and they were A1 Cardone 66-7259.  Lasted 7 years and 60k miles so far, but I suspect that unplanned Dukes of Hazard jump I took messed up at least one of them.  At the very least it's causing that clicking noise on turns so I will replace them.

I hear you guys on the OEM shafts.  I very nearly bought some replacement Cardones this morning but saw this thread in addition to your comments:

https://www.subaruoutback.org/threads/cardone-heavy-duty-axles.497231/

It really pains me to go to Pick n Pull to rip off 20+ year old parts and put them on my car, but I guess that's what I'm doing.  I'll take Imdew's advice Hopefully the employees will let me go through the gate with a jack stand so I can hold the wheel in place using the lug to break the hub nut, or I'm going to have a real fun time trying to get them off.  Forget why I replaced the original ones, maybe it was a click or just torn boots.  What a mess...

I am going to try to avoid any OEM axles with torn boots.  Hopefully I'll see a Fuji or Subaru symbol on the axles so they are easy to identify.

Oh and here's a morsel from that thread I posted above:

Sure sounds like my problem, doesn't it?  I'll let you all know what it drives like with some OEM shafts on it, and if Daskupller guessed it right. 

Will hit up Pick n Pull soon.  If anyone has had a recommendation regarding what boots to use for rebuilds, I'm glad to take it.  I may replace them in advance just to save on future maintenance down the road.

Subaru axles are green.  They should have a hard boot on them, not neoprene (unless they have been rebuilt.  Take photos of yours before you go so you can recognize them.

 

Also, for the older cars, sometimes the dealers will have rebuilt OEM axles.  They are cheaper and of the same quality.  You can also have a shop near you rebuild them for less and the quality is usually pretty good.

You will also need a punch to remove the roll pin, otherwise it will never come off.

[idosubaru]

Aftermarket are garbage.  Avoid them at all costs.  20 year old Subaru axles all day long.  You'll be fine. 

Reboot with Subaru boots and high quality grease. 

The 2000+ OEM subaru boots are high quality and last a long time.  Aftermarket boots don't last as long particularly if they're seeing.  When i started using Subaru boots I quit ever redoing boots again - do them once and they last the life of the vehicle.  When I was using aftermarket boots years ago invariably I'd have to replace one here and there. 

[dirty_mech]

5 hours ago, Daskuppler said:

Subaru axles are green (...)

You will also need a punch to remove the roll pin, otherwise it will never come off.

Thanks for the info and the reminder.  I saw earlier that my back halfshafts are green so that's solid.  And I've got a punch that fits that pin perfectly, a depth rod for an old Craftsman drill.
 

[dirty_mech]

Got an axle.  The jack stand and breaker bar method is garbage.  Was trying to attach one of those rimstands Pick n Pull uses to prop cars when a friendly guy came and helped me crack the nut on the axle with a cordless impact wrench.  About to order one of those very soon.

Here's pictures of the axle, green paint and all.  Stamps on the axle include a 63 sideways, then around the circumference is written 5 SFJ 82, with NTN Y S I H written on the other side. Cleaned it up and rubbed the boots down with AT-205.  I'm somewhat concerned about the cracking on the inner boot visible in the pictures, but I just want to get this issue resolved ASAP so I'm going to throw it in for now until the boot starts leaking.    The thermoplastic outboard boot is in mint condition - wish they could've made the inner boot of the same material.

Hopefully it's just the left side.  I'll report back when it's done.  If anyone recommends a cordless impact wrench, I'm in the market.

Edited August 10, 2022 by dirty_mech

[lmdew]

Just put a large straight slot screwdriver into the brake rotor and it will lock up the hub to break the nut.  I usually stick them right down through the brake caliper.

[dirty_mech]

23 minutes ago, lmdew said:

Just put a large straight slot screwdriver into the brake rotor and it will lock up the hub to break the nut.  I usually stick them right down through the brake caliper.

Bloody genius.  Screwdriver locks on the brake pad bracket that way.  Alright then. 😆

[1 Lucky Texan]

NTN is what you want to see. wish we had access to NTN axles, or at least inner and outer joints, without going thru a dealer.

[dirty_mech]

On 8/10/2022 at 1:44 PM, 1 Lucky Texan said:

NTN is what you want to see. wish we had access to NTN axles, or at least inner and outer joints, without going thru a dealer.

I'm starting to get what you mean.  Installed the first axle and I've still got the vibration issue, presumably from the other aftermarket axle.  (By the way, would the fact that I took the axle from a right front wheel and installed it on my left front wheel cause any problems?)

Went to a pick n pull for the second time and had no luck for the second axle.  They had 5 Subarus (2000-2004) that could've provided the axles but all were aftermarket or missing.   One aftermarket axle had these interesting blue boot clamps on them with "OET", but I assume those are also junk like the rest.  Going to have to check the other yards nearby. 

Raxles want you to call them up for a price quote and that sounds expensive, so I'll just find a second OEM one.  I was lucky to find the first in such good condition.

Just watched the first minute of this video:

https://www.youtube.com/watch?v=SxwjEaynfJQ

Seems I'll be rebooting and/or rebuilding OEM axles for the rest of time, or getting Raxles if desperate.  Lesson learned.

Edited August 12, 2022 by dirty_mech

[heartless]

7 hours ago, dirty_mech said:

(By the way, would the fact that I took the axle from a right front wheel and installed it on my left front wheel cause any problems?)

no, it will not - they are the same left to right

[1 Lucky Texan]

you could look at car-part.com

[dirty_mech]

14 hours ago, heartless said:

no, it will not - they are the same left to right

I mean I knew that much.  I just meant in terms of wear pattern, since I am installing a used 20+ year old CV axle in the opposite rotation direction for the first time in its life.  Perhaps it's actually better since all the force is now being applied in the opposite direction?  Or worse?  Or not at all as you might suggest.  I've no clue.

I just salvaged another green NTN axle off a car in another Pick n Pull and will post it shortly.  It came from the left hand side of the donor car, and I need the additional axle for my right hand side.  So now I'm in this position where I have a set of axles from two different cars, one each from the left and right hand sides, but they will be installed in the opposite of their original positions.

I don't know if this will make a difference or not in terms of wear on the CV axles. Perhaps I'll get to let you know!  I want to see if I can rebuild these at home in the future.

[dirty_mech]

Here's the second CV axle, cleaned and treated with AT-205.  Had to check about 12 Subarus across 2 yards in the 2000-2004 range to get this pair of relatively clean OEM axles.  Most had aftermarket axles or one aftermarket and one OEM axle.

This axle seems pretty good except the outboard joint is just a tiny bit stiff compared to the first one I nabbed.  I'm guessing that means I should consider rebuilding them in the next couple or few years.  Outboard boot is in good condition as usual.  The metal is more rusted than the first axle but the neoprene boot on the second axle inner joint seems to be in better  condition with less cracking. Pics:

I also ran across another set of these aftermarket axles with the blue boot clamps on a junk yard car and took a pic.  Would be curious to know their brand, I can't find any clues online:

[heartless]

10 hours ago, dirty_mech said:

I mean I knew that much.  I just meant in terms of wear pattern, since I am installing a used 20+ year old CV axle in the opposite rotation direction for the first time in its life.  Perhaps it's actually better since all the force is now being applied in the opposite direction?  Or worse?  Or not at all as you might suggest.  I've no clue.

it seriously makes no difference left or right
in fact, it is frequently used as a diagnostic tool... swap axle positions to see if there are any changes in certain symptoms - vibrations, noise, etc

 

 

[idosubaru]

Yes it can matter. You can swap axle guts or side to side to change loading and material wear internally. I knew a local Subaru guy 20 years ago who was doing that with Subaru axles.  Often it doesn’t because OEM axles have so few issues. But it can. So if you have the option change the loading. 

MWE used to be a well known reputable axle rebuilder in Colorado. I’ve bought axles from Marshall years ago when I’d drive through CO.  Great guy and axles. Some (all?) of them were painted blue. I doubt that’s the clamps you’re seeing but it’s the only blue axle related thing I can think of. Probably more likely just a local store had a brand with clamps like that. 

[dirty_mech]

On 8/13/2022 at 10:08 AM, idosubaru said:

Yes it can matter. You can swap axle guts or side to side to change loading and material wear internally. I knew a local Subaru guy 20 years ago who was doing that with Subaru axles.  Often it doesn’t because OEM axles have so few issues. But it can. So if you have the option change the loading.

If by change the loading you mean swap them from left to right and vice versa, I've done that. 

I saw that it's recommended when changing ride height, which I also did a couple years ago.

Swapped the other axle off the passenger side and discovered it has tons of play in the inner joint.  Apparently there's a way to check for this but the Les Schwab guys don't go that far.  You can grip the bucket and the shaft and try to rotate each side against itself to check for play.  Test drove it and the issue is mostly gone.  The ride still feels slightly rough like maybe the bearings are a bit old or that stiff outer joint is generating a tiny bit of friction.  Not sure.  Maybe I'll change the wheel bearings at some point if its recommended for a smoother ride. 

I'm not sure if I can do any preventative or preemptive maintenance on the joints themselves to eliminate stiffness and prevent wearing.  That outer joint on the passenger side OEM yard axle was noticeably stiffer than the first one I got.  Would it be that to "swap the axle guts" might do the trick?  Is that caps and/or needle bearings that can be swapped, or more?  It would be solid if they sold a good kit for something like that. 

So glad I can get back to roadtripping without having to worry about that vibration developing again. 

This guy's story closely tracks everything I experienced:

 

Edited August 15, 2022 by dirty_mech

[forester2002s]

You may have already done this, but if not I would change the rubber-boots and clean out the CV-joints.

Most new boots come with replacement grease. It's fairly easy to completely disassemble a CV-joint, and to clean out all of the existing grease. Once clean, it's easy to inspect the mating surfaces, and to see if there is any surface-wear. The Subaru OEM CV-joints are a thing of beauty, and are well made.

Add the fresh grease, reassemble and re-boot.  This might help with problematic vibrations. But in any case, it's a labor of love, a kind of Zen thing.