2013 Quest - Odd pulsing thump - not speed or RPM related

[commanderclif]

My wife's Quest van has an unusual, intermittent issue where an odd thumping will start somewhere in the front passenger side wheel or maybe even closer to middle engine area. I've tried to test drive it and get it to reproduce the sound in the past and got nothing, even doing a long distance trip at Thanksgiving with no issue. However last night she came home and said it was doing it so I took it for a test ride, nothing at first but eventually I got it to occur.

First of all, it's independent of RPMs or speed, so not immediately tying it to engine valves, or anything in the tires/wheel/brakes. It came on while driving a consistent speed and somewhat of a gyroscopic like spin up sound and feel that started out a slower and then built to a slightly faster rhythm but leveling out and being consistent. Speeding up, coasting or maintaining speed had no effect on changing the sound or its rhythm. Maybe, by applying brakes there was a bit of a muting and bring the car to stop would have it wind back down and stop. It was as if as the van got moving something started to slow sway/pivot/rocker that would progressive move more until it made a sound and bringing the car to a stop would have the motion dissipate as it came to a stop from moving.

Last year the struts were replaced but I don't think anything has been done in any of the controls arms or tie rods. Quest has over 100,000 miles.

Again, the rate of the thumping noise neither increases or decreases with speed, so can see there being an issue in the wheel rotation the way a flat tire would. Also, with the car in park and revving the engine there is never an issue, it has to be in motion and then in some sort of position or road quality that has the rocking sound to even begin. Not all roads, at all times.

[spamcop01]

Any chance you can capture the sound on a video and upload it to YouTube (YT)? That might help us diagnose it, and further, if you solve the problem you can add the solution to the description on the YT page. I had a problem with "clicking" sounds coming from the rack & pinion on a 2005 Acura TL several years back and posted a YT vid. A local mechanic had to use a stethoscope to nail down the exact source. I don't care about internet clicks, but that video has received over 43K views and 100 comments.

[commanderclif]

I'll see if I can capture one. My wife made one but it's not good, I heard the turn signal in the video and not much else.

[commanderclif]

Well, I'll be damned. Took a look at the Quest in the light instead of night time test drive and noticed front passenger wheel is missing two lug nuts. In fact one of them is missing the wheel stud, guessing it broke off. No idea when but even the other lug nuts weren't tightened. I'll be replacing the wheel hub this weekend, but a nut on the stem missing a lug nut and got all four tightened up for now.

Odd thing, last time wheels came off was when the dealership replaced the struts. They suggested a tire rotation at that time at a low price so I went ahead and did it. The passenger rear tire has as 5 lug nuts on but they are all standard, one should be the lock nut I have on each wheel. Both tires on the drive side have lock nuts and are appropriately tightened. So where are the missing two lock nuts? Could guess that one was one of the missing two and it fell/broke off. But were BOTH lock nuts on the same wheel? Where did they get an extra nut from if not? Or was there one missing all along?

Exhibit A for why I HATE to take a vehicle to a dealer repair shop.

[spamcop01]

That's pretty scary and glad you found it! They're going to deny any responsibility, but you've got to talk to the shop manager. Not sure if I mentioned it in the first thread you started, but when I replaced my front struts a few weeks ago, I found that neither half-axle had a cotter pin. I bought the Quest used with just under 25K miles, and until I replaced the half-axle, I couldn't think of another repair that would have required removing the cotter pin & axle nut. So I'm inclined to believe it happened at the factory. Regardless, I put new pins in.

Last thing: please be sure to update your other thread with your findings.

[commanderclif]

Dang, putting the cotter pin in is the easy part! I'll be making sure I put it back in when I'm done with the new hub! I'll report back that problem is indeed resolved. After tightening the lug nuts I test drove yesterday and it did happen but of course I have to remember it was intermittent but it certainly was happening more frequently recently. THANKS!

[spamcop01]

I'd be curious to know if your half-axles have cotter pins in. You're probably aware, but cotter pins aren't meant to be re-used. If you're anywhere near a dealer, you can buy new ones for like a buck each. Otherwise, AutoZone has a pack of 12 for $3-4. Good luck!