Recently purchased Legacy has knocking sound when coasting and/or hitting bumps in road

[cgates30]

The knocking sound is coming from the left front of the car when I hit bumps in the road and when I'm turning to the left. There might be some rattle on the right, but not very noticeable and not when turning. 

I'll squirt some simple green under the car to see if I can clean it up and then start watching for leaks.

I haven't changed the struts yet, so if I can isolate the problem to the axles first then that's where I'll start. Will start looking for OEM axles...

[idosubaru]

A "free" diagnosis would be to swap the axles from left to right since they're the same.  If the symptoms move, or change, then you know the issue is with the axles. 
(the symptoms may even go away since by swapping sides the loading on the bearing surfaces shifts entirely 180 degrees out).  

That's probably what I'd do at this point if I were you: 
1. pull the drivers side axle and swap it for the passengers side. 

2. while the axle is disconnected from the drivers side strut you can twist/turn/pull on...or even remove the strut and inspect it. 

 

If the symptoms started after a strut change then that's the fist place to consider. 

Aftermarket axles, while terribly unpredictable, would probably come in second after a clear "no symptom" to "symptoms" event like the strut change, if you're positive that's the timeline of how it happened. 

I say "if yo'ure positive" because sometimes a symptom can initiate a repair, a noise happened in the winter and with loud music playing and heater blowing on high it didn't seem loud and you had the car going into the shop anyway "i think i heard something...and wanted to do struts anyway...let's do struts"....but then later you forget that a noise actually precipitated the strut replacement but the noise is now louder because the windows are down in the summer and you're paying more attention.

[1 Lucky Texan]

any 'thunk' noises starting forwards or backwards? if so, check the rear bushing on the lower control arm too.

sway bar endlinks worth a look too I guess.

 

Edited August 6, 2018 by 1 Lucky Texan

[cgates30]

I swapped the axle shafts and am still getting the sounds on the left side of the car. All of the bushings "look" good, but some easy/cheap to replace, so I'll do that next. I'd like to see if I can diagnose the strut mount.

By the way, one of the axles is most likely an aftermarket model. The hole in the collar that slides over the inner spline doesn't perfectly line up with the hole in the spline shaft. When I removed the pin it came out in parts. Also, try finding an M6x45 roll pin on a Saturday. Not around here, not even the local Subaru dealer had any. I ended up using a 7/32" (which under normal circumstances would be too small, but the misalignment just mentioned was enough to require a good bit of tapping to get it in). Long term I may replace that axle (now on passenger side), but for now I guess it is where it is.

[el_freddo]

That shaft that is half a hole out is fitted 180* out.

pull it off, rotate 180* and refit, the hole will line up perfectly for the proper sized pin

I'm still sticking with the strut being the issue with this clunking sound you described earlier. Classic symptom. 

Cheers

Bennie

[cgates30]

On 8/11/2018 at 11:03 PM, el_freddo said:

That shaft that is half a hole out is fitted 180* out.

pull it off, rotate 180* and refit, the hole will line up perfectly for the proper sized pin

I'm still sticking with the strut being the issue with this clunking sound you described earlier. Classic symptom. 

 

1

Yeah, I think it is the strut. There's that knocking sound that comes/goes but is more prominent when veering to the left and then there's a clanging sound when I hit bumps. The left side is worse than the right, but I think it comes from both sides when hitting bumps.

 

[idosubaru]

You misaligned the axles pins - they only line up one way - you need to rotate it 180 degrees and reinstall it.

 

 

[cgates30]

No update on the pins holding the axles. However, I did do some cleaning of the engine compartment to see if I can find any leaks. The result was not good. I got some water that is causing P0302 cylinder 2 misfire. In troubleshooting that I discovered the plug wires had been pulled out by the wire and the clamp over the wire insulation was mangled. Subaru didn't have new wires and I didn't want the Duralast from Autozone, so I'm waiting till this evening for my amazon delivery of NGK wires/plugs.

Also, I was able to get a recording of the sound I hear. It starts at about 5-6 seconds into the recording.

https://photos.app.goo.gl/xHjHNLYaMwh7wVRM9