I'm watching this, as my mechanic says my clunk may be internal to the strut, as everything else checks out OK.

A word of caution on those remote sensors. I used these as a diagnostic tool as a development engineer and found that the cheap accelerometers have different sensitivities. We confirmed this by clipping all four to the same spot and listening to them one at a time. Sure enough some were loud and some were not.

The once per wheel rev knocking is baffling. Torque and steering input would point to a half shaft or differential bearing maybe???

 

It's going to take me a few days yet for the next iteration... Turkey Day and all that you know.

Your point about the repeatability of sensors is well taken. I spent a career in nuclear engineering and understand the issues of properly calibrated stuff... Still in all, this is what's reasonably available and within my budget.

What I do is use these to isolate noises and then listen for the pattern of the noise, placing less emphasis on the loudness of what I hear. A long time ago, in a place far, far away... I had some u-joints that kicked my behind trying to figure out "what that funny noise was." Turned out the failing u-joints noise was being transmitted down the propeller shaft and so the noise was appearing elsewhere! Took me weeks to figure it out.

In this case the critical initial questions were: is it in the transaxle or engine. Clearly not after I put this ChassisEar on. Very useful data points, as I was seriously concerned about the transaxle.

So now where is it coming from and why is it in sync with wheel rotation? The issue of the CV halfshaft is appropriate to consider, yet if it were the plunge joint (next to transaxle) the cyclic rate would be 3X and if it were the flex joint (at the knuckle) it would be a 6X cyclic rate. Since it is 1X, I infer it is some kind of slightly out of balance thing with the wheel energizing the lower arm arm once per revolution through a failing resilient mount.

My take for the moment is that the lower arm is my next step (~$50-60). There are two resilient mounts on this and if they are giving up the ghost, metal to metal contact would happen and would be cyclic. If I were a betting man it will be the rear of the two mounts that is failed (eg a vertical arrangement) rather that the front of the two mounts (a horizontal arrangement).

If that doesn't work then the strut itself is suspect. Since the noise is louder below the spring itself loose mounting bolts at the top, which I've looked at, seem not the problem, thus a strut with some kind of failure appears the next step.

Onward...!

 

2005 FEH at 121,000 miles. First 95,000 miles only had wire for engine block heater go out and two cracked tone rings. Yes I did have the brake rotors replaced. Then a speed sensor failure with another crack tone ring caused AWD and drivability issues. 115,000 miles a coupler for the AWD system and multiple items on the front end suspension needed replacement. Rust noted on rear passenger side wheel well despite it going to Ziebart. Had the MECS pump replaced at 120,000 miles not because it failed but because I didn't want to chance it.

Max mileage (mpg) tank was 43.5---tailwind for 200 miles helped!

Waiting for the new Ford PHEV in 2018 which will hopefully have an AWD version.

 

Installed the lower arm, surprisingly straightforward, although not easy. No change in knocking sound. It did seem to take longer to begin but when it did it was the same.

Today started looking at the sway bar/stabilizer bar. Took off the bracket holding the bushing in place. Found the bushing in reasonable condition.

However, I found it installed backwards. The split is supposed to be facing the rear. As found the split was facing forward.

Frankly it's difficult to see how this alone could be the cause. Still, I finally found something that was not correct.

Have to think on this to see what makes sense. Will reinstall properly and see what happens with the knocking.

 

Thanks for the update. I'm learning to live wiith my knock, now that I know it is not a safety issue. And wow, does my wife like her new CRV.

 

Went in and looked at the pax side bushing. It also was installed backwards. Specifically, the shop manual calls for the bushing to be installed with the split facing to the rear. It also had the split facing forward.

Not at all clear that this could produce the knocking sound I'm hearing. On the drivers side there was some amount of small gravel in the cupped area beneath where the bushing bracket bolts up. But at least I found something wrong.

This gravel could in effect cause the sway bar to contact the frame. Still the cyclic nature of the knocking causes the inference of something else as the cause.

 

Just reinstalled the pax side sway bar bushing. No big deal. Note: it is worth chasing down the threads as they are in a place where dirt and water gets on them easily.

While reinstalling the bushing rear bolt (you have to get underneath and look forward) looked over the sway bar itself to see if it was correctly seated. Noticed that where it goes downward and forward toward the drivers side wheel (and over the underframe) that it was less than a little fingers width away from the underframe. On the Pax side for the same place the clearance was well more than a full fingers width from the underframe.

Since it is only held in place by the bushings and the two end point links to the struts, it can be moved somewhat side to side. So I moved it to equalize the clearance to the underframe in each place.

Road test to follow. As I see things if this were the cause it would be positioned to contact the frame and cause noise at the strut & link attach point and right underneath the driver.

Hm-m-m, if this turns out to be the issue...

 

Well... the sway bar thing wasn't it.

Did some work on the drivers side wheel & brake caliper to ensure there was no interference. Took out on a test drive with ChassisEar sensors installed.

The noise was most pronounced on the strut midpoint at the sway bar link attach point. It was also present on one of the bolts that mates the strut to the steering knuckle. It was fainter on this second sensor.

So... everything comes back to the strut itself. What baffles me is that it is cyclic. It's as if the welded joint where the strut tubes mates to the cast iron unit that attaches to the steering knuckle is wobbling from a weak & failing weld.

There was zero noise on the brake caliper and the lower arm. On to replacing the strut.

 

Installed the new strut (drivers side front). Fixed about 80% of the problem.

With the chassisear the notable knocking was on the sway bar link attach point midway on the strut. It is now gone there.

Knocking now only occurs when doing a gentle left turn. The knocking only shows up on the tie rod. It is present but not loud.

Will have to reflect on this.

 

Did a long trip (~80 miles). Knocking virtually gone. There is one angle of left turn where the knocking pops up.

Curiously, the knocking shows up on the steering gear. Set up with one sensor attached to one of the steering gear bolts. Go figure. The ChassisEar system has been useful here. But what in the world on or associated with the steering gear could cause cyclic knocking?

My take now is that I fixed one problem with the new strut pack and uncovered another one.

PS Sent off an email to RockAuto regarding the Monroe Lifetime warranty on this strut pack. Will let you know how it works out.