Thumping Sound When Wet

We're in the midst of our third Florida rainy season with our 2010. In years past, there hasn't been an issue or if there was, it wasn't enough to notice and we had a pretty wet winter with lots of rain, but the problem just started a couple of weeks ago and the only thing I did recently was rotate the tires (making an X). Though, the rotation was just a few days before I started hearing the noise.

What happens when it rains, for the next couple of hours, there are multiple spots of standing water on the roads. It is impossible to go anywhere without driving through the puddles, some of which may be as much as four inches deep. Of course, what most people do is try to drive the crest along the center lines when you can, but even then at least the passenger side goes through an inch or so.

I don't know where the divide is, but a few puddles isn't a problem. It's worse when there's more and there's no way to avoid them except by never leaving the house because when it rains, it often pours.

After driving through however many puddles, I get a thumping or clunking sound from the front passenger-side quadrant of the car. It is not from the ICE because it's the same in EV. The way I'd describe the noise is that it's like when the tailpipe supports rust out from under a '73 Nova and it bumps against the bottom as it idles, except I've checked the exhaust and that's not it, plus it seems much further forward under the car.

Sometimes, it's kind of rhythmic, like it's going with the tire rotation especially at low speeds, but it's not rhythmic every time you're going very slow and when it is, it sounds more like a flap. It kind of seems like when you let up on the gas, even a minuscule amount, it could get worse, but the noise is also there while you're trying to go steady, so I can't really say the regen may be involved.

Also, I haven't driven faster than 45 while the car is thunking. I have taken it on the highway at a steady 75 since I've been hearing the noise, but those trips haven't coincided with rain. All of my daily driving is on residential and suburban streets.

Problem is that it only happens after driving through some number of puddles and though it rained every day for a week or so, it's not raining every day now. When the weather is dry, the car doesn't make the noise. Though, if you drove through a lot of puddles toward the end of one day, there will be some thumping the next AM until you've driven... maybe... ten miles. The next morning clunks are less than when it's wet and again, I generalize that it doesn't happen from three puddles and it takes more like fifteen.

Any thoughts? Anything anyone could suggest to check?

I've looked at the brakes and they look fine. I haven't taken them off, but the front passenger side pads and rotor look fine. I've also done the neutral thing to use only friction brakes, but the noise is just as loud. The tire holds its air, so it's not from deflation. With both front wheels up, the tires spin and there's no play forward and back. Everything underneath looks as intact as it has for years.

I don't yet know if you can hear it outside the car because though I could have checked yesterday, I didn't think of it when I had both puddles and a second driver. Also, I tried soaking the passenger side wheel, rotor and brakes with a hose, but that didn't produce the noise. I didn't think that maybe I should have soaked the other side until just now, but everyone agrees that it seems to be coming from the passenger half of the car.

Carista shows no codes or faults, even in the midst of the clunks. There are no dashboard error lights.

I don't know what else to check. Searching this forum and the web hasn't given an answer. I'm stumped.

I'd appreciate any DIY suggestions.

Thanks!

TLDR: Clunking or thumping sound seemingly from the front passenger side when the underside of the car is very wet. The noise isn't subtle. Inside the car, it's loud and can't be missed. Problem recently started and everything visible looks fine.

 

I've tried shaking some things. I could try shaking some more over the next couple of days or putting it on ramps so I'm more comfortable under the car, especially when shaking to see if I can find anything loose because that could quite possibly be the sound, but I haven't figured out why it'd only make noise after multiple times driving through water.

When the car is dry, there's no noise and if you drive through several puddles, it happens so little you might not notice. It's after you've driven through like fifteen or more deep puddles that the noise becomes loud and constant enough that if you didn't know it'd subside once everything is dry, you'd be reluctant to drive very far.

I'll try shaking some more and will see if I can visibly inspect those bolts. Thanks for the suggestion.

 

@Patrick Wong: Prior to first hearing the "little bit of noise" from a few puddles 22 days ago, there was like a week when there were multiple waves of downpours every afternoon. Then, after first hearing the noise and as it seems to have progressively gotten worse, but that's really only a subjective measure and could be influenced by my driving around looking for puddles, the downpours lately have been coming like every four days

I had been focused on searching this forum, eliminating a couple of other possible causes and staying out of the lightning during the rainfall. The forecast makes it look like I'll most likely have to wait at least a few more days for the next big rain, but if the noise persists, I'll try shaking things, then.

@schmuber: I don't know that there's any undercarriage car washes around, but I have thought about straddling one of my big sprinklers for a while, but I wasn't sure if making it rain from up under the car was the best idea. (Day before yesterday, I was trying to correlate the noise to the energy screen and yesterday it only rained for a few minutes producing short-lived puddles, so I took the passenger side wheel off, looked at the brake and tried my hose trick)

I don't know that I'll have time to try it during the daylight today -- my wife drove it to her office and we both have meetings this evening -- tomorrow evening she'll want to drive her car to a different meeting, but unless someone says I shouldn't, I'll try straddling a sprinkler during the daylight and if that produces the noise, I'll jack-up the front end and freespin the tires as soon as I can.

Thanks!

 

@edthefox5: Interesting... I had thought about rotating them back, but it was a lot of work to do by myself, so I wasn't jumping to derotate. After reading your response though and using it as a basis to search the forum, you may be on to something.

To be honest, it was the first time in a couple of decades that I rotated my own tires. I remember when this set was just a couple of thousand miles old, my wife and daughter dropped it at Sears for the free rotation, but that didn't end up being very convenient or fun for them and I hardly ever go to the mall myself, so we put another 30k on them without rotation.

A few weeks ago, it came to my attention that by not rotating the tires every 6 to 8,000 miles, I had voided the tread warranty on this set. Though it wouldn't count because the warranty was already voided and I wasn't going to make any kind of record of my rotation, I decided it would probably still be for the best because the tires would have been pro-rated warrantied for another 15,000 miles.

I'm guessing from my reading of your reply and other threads that after 30-35,000 miles, the wear pattern on these tires were pretty set and I can understand in theory that it could cause excessive noise, which the wetness might exaggerate into what can only be described as a horrible sound. My best back-of-the-envelope math says the tires have been about 700 miles since rotation. Does anyone think I'd do more harm than good by putting them back?

@CR94: While I haven't actually crawled underneath, the plastic cover looks to be as intact as it's been for three years. It's not perfect, but from looking under, it appears the same as it has been for 80,000 miles.

Any thoughts or other suggestions are welcome. Thanks!

 

@Patrick Wong: I've looked to see if I can find some kind of notation. They are Uniroyal Tiger Paw Touring. The manufacturer's page is very sparse. I'd say there's more info on the listing linked from my receipt from Sears. I see nothing that says direction.

Thanks

 

@Mendel Leisk: Not a lot of parallel parking in my part of the world.

@Everyone: There's not a big chance of rain again today, so I'll try to do the sprinkler thing this PM.

It sounds like we've come back around to the idea that derotating the tires without a lift could be unnecessary work, but I don't think anyone can really say that for certain until the noise is eliminated.

When I looked at the tires prior to rotation, I'd say they looked evenly worn, but I only eyeballed them and didn't actually measure. They've also been around 30k miles over the course of a year, so maybe though it's not super-visible, a pattern has formed. IDK

Thanks for all of the suggestions and the discussions. That's something great about this forum.

 

Update: No Progress

Instead of straddling a regular sprinkler, I bought one to go on the end of the hose and tried spraying up multiple points under the car, both the middle and right of the front, and one time under the middle of the back. I only let it go for five or six minutes in each spot, but I feel it was most likely enough to do whatever spraying-up would do.

I might try it again in a couple of spots during the daylight hours tomorrow, but I'm thinking that whatever it is making the noise may need to be immersed and the chance of thunderstorms is only hit or miss for the next few days.

Because I'll be able to work on it during daylight on Wednesday, I could put it on the ramps and give things a good shake.

Any and all ideas are welcome. I'll update this thread when I know more.

Thanks!