Clunk Noise on front left wheel - Subaru Legacy

In the past week a noise on the front left wheel side started becoming every day more prominent. It goes at the same frequency as the wheel is rotating. The vibration can be felt on the steering wheel as well. ANy suggetsion as to what it could be?

The mechanic said it could be the axle CV joint, but probably not the ball bearing; it could even be the transmission in his opinion. He injected some grease in the booth of the axle to see if this was going to change anything, but there was no change.

Eventually we decided to try replace the axle, but as he started taking down the wheel and extracting a couple of pins, he became more convinced that the axle was OK, so he recommended that I take the car to the dealer to diagnose if it was indeed the transmission.

When I left the mechanic's garage the noise had disappeared, and never came back by the time I reached the dealer. So I didn't go through any diagnostics as it would be wasted money.

Any suggestion on what this could be, and what to check? The car is a Subaru 2003 Legacy station wagon with 118,000 miles on it, 2.5 L engine.

 

Until you said it went away, I was ready to suggest a tire going bad from the tread separating. My best guess would be that somewhere in the process of going as far as the mechanic went he inadvertently stumbled across the problem without realizing it.

 

This actually was the second time the mechanic had put the car on the hoist to check it underneath. He examined both times treads, brake rotors and axles. Only the second time he started taking something down. What I also asked them to do the second time was to turn on the car while on the hoist, put it in gear and spin all 4 wheels to at least 30 mph. First they spun the incriminated side without the wheel on; then because it was almost not moving (the differential transferring most of the rotation to the other wheel), they mounted the wheel back and they spun it again. I'm wondering if this has something to do with a problem in the differential that the uneven rotation hid away.

 

Possible, but I'm not sure you would feel transmission/differential problems in the steering wheel. I'm more inclined to think a cv issue of some kind. Last time I had to deal with a cv personally it showed up as a pronounced shake in the front end when accelerating, especially when hitting the freeway on-ramps. I'm not much of a Subaru expert (can't tow them on my wheel lift wrecker since they're AWD), so I don't know what Subaru-specific items might come into play, in particular anything in the AWD system.

 

Thanks tow guy for following up. I agree CV is a possibility, but when the car was hoisted, moving the axle by hand didn't show any significant play. I wanted to add further piece of the story that may or may not be related to what's going on right now.

About a month ago a grinding noise started on the other side (front right hand side). It was at the same frequency as the wheel, and I thought it was something caught in the brake rotor, but nothing was showing after taking the wheel down. It appeared at the beginning of a 100-mile trip, and the next day was not there anymore. It had the same period as the clunking noise, but just grinding this first time. I could tell that it was metal on metal, and not with a lot of energy dissipated, but it was definitely there. The next day I went to the mechanic, and we couldn't find anything.

 

Do you have a long-term relation with the mechanic? I'm thinking maybe a fresh set of eyes/ears/thoughts on the problem wouldn't hurt, but have to be careful of treading on toes if you've been with the first guy for a while.

 

Yes I do have a good relationship with him. However, he's the first who proposed that I go to the dealer for a second opinion, since he said he couldn't be sure of what it was.

 

I like mechanics who aren't afraid of suggesting other opinions. Although I'm not a big fan of dealer service, sometimes they are the best choice.