Mysterious Clunking! [Solved]

2366 Views 8 Replies 7 Participants Last post by Replays, Mar 23, 2019

TeeRev

Discussion Starter · Mar 19, 2019

So, about the mysterious clunking I mentioned in the "What Did You Do to Your Impala Today" thread...

About three weeks ago, every once in a while I'd hear this "clunk" coming from the back of my car when braking. It didn't happen all the time, and it wasn't 100% repeatable. Of course, it was driving me nuts. It seemed to be coming from the back right of the car.

I checked the wheels, the brakes, the suspension, nothing. Then the sound went away and I didn't think anything more of it. But... the sound came back a week later. When braking and sometimes letting off the brakes at slow speed, there'd be a clunk. Clunk. Clunk. Clunk. Drove me absolutely insane.

Finally, and I don't know why it took me this long, I decided to see if it could be something within my trunk. So I emptied it out, yanked the mat and carpet, checked the spare tire well, nothing. Then I looked at the side, and guess what I found?

A veritable swimming pool in my trunk. With a foot-long (literally) chunk of ice floating around. The backwards / forwards motion of braking would cause the water to slosh around and the ice would hit the body, causing that "clunk" sound. The reason the sound was only present for a day, then went away for a week, then came back was because it finally got over freezing outside.

There was no water anywhere else in the trunk, or in the "well" on the opposite side. I know the water didn't come from the top (i.e. the tailight area or the trunk lid) as I have a waterproof mat that covers the entire trunk floor, and the carpet and sides were completely dry. It must have been a bottom-up splashing of water, I believe from the vent (black plastic vent in the side wall over the puddle). I must have scooped out 30+ oz of water, not including the hunk of ice.

I wish I had taken a better picture of where the swimming pool in my trunk was located. Best way I can describe it is that it is in the back right corner of the car. Just behind the passenger side rear wheel.

Has anybody else on this forum experienced something similar?

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12 lt

· #2 · Mar 19, 2019

Thanks for sharing. Seems a strange place for water to get in. Have not had that issue, but will be certain to remember this.

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jtrosky

· #3 · Mar 19, 2019

My guess is that it came in the little vent. I've seen those before - I think it was with @LazerBlue's Impala? Maybe from a car wash (high pressure water making it's way into that vent)? Or if you drove through high water?

That vent is these to supposedly let air out (like when you close your doors with the window up, the air pressure inside the car gets relieved somehow - through that vent - at least that is my understanding of why it's there...

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TeeRev

Discussion Starter · #4 · Mar 20, 2019

jtrosky said:
My guess is that it came in the little vent. I've seen those before - I think it was with @LazerBlue's Impala? Maybe from a car wash (high pressure water making it's way into that vent)? Or if you drove through high water?

That vent is these to supposedly let air out (like when you close your doors with the window up, the air pressure inside the car gets relieved somehow - through that vent - at least that is my understanding of why it's there...

Yup, that's how the vent works, I believe, and my main suspect as well.

I haven't driven through high water, but I think you may be on to something with the high pressure underbody wash at the car wash. Good idea.

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Joes74challenger

· #5 · Mar 20, 2019

weird thing is i always had the underbody washes done on my 2010 and never had a water issue in the pockets (i checked them periodically and they were always dry.

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plano-doug

· #6 · Mar 20, 2019

Joes74challenger said:
weird thing is i always had the underbody washes done on my 2010 and never had a water issue in the pockets (i checked them periodically and they were always dry.

It would have to be a lucky shot. But I've seen sprayers before (in a bottle washer at a soda plant) where some of the jets get wonky such that an extra strong stream can be coming out. It would only have to hit the target for a moment to deliver enough water to make the icicle TeeRev posted.

Doug

.

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jtrosky

· #7 · Mar 20, 2019

Keep in mind that it's just another off-the-wall "JT theory", so it is VERY possible (maybe even probable) that it's completely false... ;-)

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dtnel

· #8 · Mar 22, 2019

I've had a clunk for years and it's not water related. It's suspension related I believe. Replaced rear struts with a quick strut kit, replaced stabilizer links, the lower easier to replace cross beam bars, the forward to front of axle lateral bars. Only thing I haven't replaced is the sway bar. Replaced the bushings at the same time I did all the other stuff.

It is mainly worse when people are in the rear seats , 1 or more people and the lore the worse the sound. Wheel bearings, brakes and rotors have also been replaced. All this was done as a 10 year complete suspension rebuild which was roughly $1200 in parts including the front rack & pinion, front quick struts, front sway bar and sway bar links. This didn't include an alignment afterwards which was around $70 or so give or take.

Sent from my SM-N960U using Tapatalk

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Replays

· #9 · Mar 23, 2019 (Edited)

dtnel said:
I've had a clunk for years and it's not water related. It's suspension related I believe. Replaced rear struts with a quick strut kit, replaced stabilizer links, the lower easier to replace cross beam bars, the forward to front of axle lateral bars. Only thing I haven't replaced is the sway bar. Replaced the bushings at the same time I did all the other stuff.

It is mainly worse when people are in the rear seats , 1 or more people and the lore the worse the sound. Wheel bearings, brakes and rotors have also been replaced. All this was done as a 10 year complete suspension rebuild which was roughly $1200 in parts including the front rack & pinion, front quick struts, front sway bar and sway bar links. This didn't include an alignment afterwards which was around $70 or so give or take.

Sent from my SM-N960U using Tapatalk

Funny my 2012, which has a long nightmare story I’ll tell if I can ever get time(electrical, trans, speedometer, traction control, hubs, stabilitrak, and many more general electrical problems), had a clunk that sounded like coming from under car toward rear maybe even right under passenger seat and was driving me crazy. Checked all suspension, brake system, all bushings, etc. and couldn’t pinpoint it.

Next focused on exhaust because was more evident on bumpy roads and sounded like it could be muffler bouncing around, found nothing.

Finally had car in air repairing the electrical problem mentioned above and just started pushing/pulling on everything under car. Was the dang shield over gas tank. Hit it with my hand and it clunked. At front of tank the shield was sitting against underbody of car and every time car hit a bump or driving fast on uneven roads the shield would come off the body and slam back against it. Popped push-ins out that were closest to that area, shield dropped down some, little light bending there and opposite end to make it sit flat against tank again and not touch underbody in any way, and noise is gone.

Been a mechanic 30 years and I have never seen such a thin piece of metal make such a loud noise. Noise sounded like someone hitting something in rear end with a small hammer.

I’m not sure what gens have the shield but if it does check all the way around it and tank to see if shield is touching body anywhere. Can’t remember if my 2010 had the shield or not, been a while since was under it and it has moved on thanks to a deer on a long dark highway. And sure can’t remember if the 2004 had it, that was way too far back lol. Damn I’m getting old. Anyway, just trying to say don’t discount the shields that cover everything under the car, I did at first and it cost me a few months of frustration before I finally figured it out.

Will get back when have more time to tell the story of the 2012. Wanted to share because this forum has helped me tremendously over the years. Always been in such a hurry never even created an account until a couple months ago. So feel like it’s time I give back a little since have to slow life down some, or more accurately life is slowing me down.

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Mysterious Clunking! [Solved]

TeeRev

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12 lt

jtrosky

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