Whoop Noise While Moving

[Sal]

I have 98 Explorer XLT AWD 8cyl with 142K miles. I've been trying to track down a whoop-whoop sort of noise I get while rolling along. It isn't coming from the engine. I notice that when the car sits for a while (overnight) I won't hear the noise until I travel a short distance of say a mile or so.
If I apply the brakes a bit the noise is eliminated or at least quieted down to where I don't hear it.
I believe I hear the noise coming from the front of the vehicle.
I check the play in all the wheels by pushing and pulling from the top & bottom. There wasn't any noticeable play.
I also checked for bearing noise by turn the wheel left and then right while moving along at a fairly low speed. The noise was there only when I leaned towards the left (loading the right side). I swapped out the front right hub bearing with a new one but the noise is still there. I'm not too surprised because the wheel turned fine with the old hub and, sure enough, after I removed the old one it seemed to be in good shape.
I have about 1/8" play when I pull on the rear wheels (in and out). However, I read that is typical and something to do a C clip used to retain the axle.
I suppose it could be the rear hub. However, when I check it, all seems OK so I'm hesitant to replace the rear right hub.
Also, the front L/S half axle and the front axle were both recently rebuilt by a good rebuild shop and are in like new condition.

I'm going to try to get the truck up on a lift and put it in gear to see if I can pinpoint the source of the noise.
Brake pads, rotors and calibers all seem OK.

Any ideas of where this noise might be coming from?

 

[German Engineer]

Very detailed description, still a "whoop noise" is kind of hard for me to relate to, but here's my best guesses:

- Did you check the wheels and tires for any possible damage?
Your Explorer should have working ABS, so brake marks are rather unlikely, but not completely impossible to occur, because once even smaller brake marks appear, they tend to get worse and sort of "grow" with repeated braking due to the tire tending to start slipping at the same spot again and again.
Also - and in your case probably more likely than brake marks - you could have a locally damaged sidewall and/or carcass causing the tire to not to roll correctly making noise (This can be very hard sometimes even nearly impossible to spot visually and requires you to look very carefully for any irregularity in shape).
You could have a damaged/ dented rim.
And last but not least you could possibly even just have an unbalanced tire, but that again would likely be a result of local damage or an applied counter weight falling off.
All these things can commonly occur after rolling over a pot hole or a bump or an object or hitting a curb hard enough.

Other than what you already checked and the wheels and tires
you could:
- Check the serpentine belt (and any devices driven by that).
- Check the Fans if they run right.
- Check your sound system and speakers. (Yes I know this is probably kind of a silly suggestion in your specific case here, but radio and amplifiers can make really strange whoop noises too when there's electric interferences with whatever, like a bad alternator or plugged in devices etc.)

 

[RandomNerd2000]

Check your tires for lumps, I had this and turns out I had a Goodyear Wrangler Radial with broken belts, try rotating tires, it's free and if it helps, you moved the guilty tire from front to back.

 

[Sal]

All excellent advise but I should have mentioned the tire & some other history as well.

The Tires are Good Year Wranglers with 14K miles on them, 3 years old. I had the tires rebalanced and rotated.

All is in very good running shape. No check engine, ABS system is fine, Brake system fine. I don't feel any pulsing when I brake.
No pulling/ Stops Straight. Handles the road with no pulling at any speed. Tight suspension. 2 years on shocks & upper/low control arms, tie rods.
I did a brake job last June and the brake caliber and pins were working fine. Cleaned & regreased pins. Rotor surface is smooth.

Noise is coming from some component that rotates when the vehicle is moving.
Engine RPM doesn't change anything and neither does transmission gear between neutral & D.
The only way to lower the sound that I know of is leaning the vehicle left & right while moving. Lean left and right side loads with more noise. Lean right and noise goes away. The noise is also gone when I apply, even lightly, the brakes.


I wouldn't rule out the rims, rotors or tires even though they seem fine.

My best bet might be to get the car on a lift and put it in gear.

Great advise. Much appreciated!

 

[German Engineer]

…
...
Noise is coming from some component that rotates when the vehicle is moving.
Engine RPM doesn't change anything and neither does transmission gear between neutral & D.
The only way to lower the sound that I know of is leaning the vehicle left & right while moving. Lean left and right side loads with more noise. Lean right and noise goes away. The noise is also gone when I apply, even lightly, the brakes.


I wouldn't rule out the rims, rotors or tires even though they seem fine.

My best bet might be to get the car on a lift and put it in gear.

Great advise. Much appreciated!

That really sounds an awful lot like a damaged tire, probably the front right one. Seems like it's making more noise when the car leans in a left turn and the tire has more load and the tire's sidewall is being bent inwards.

A tire can really get damaged instantly, from one second to the next, when hitting a curb or rolling over a gutter or pot hole hard enough. The history or age of the tire doesn't necessarily have to mean all that much here.

Another, but really awfully vague idea could be that something is scraping on the brake rotor, like a bent dust shield, but that usually would not sound much like a "whoop".

You could just try replacing the front right tire with a spare and then drive the car to try and see if the noise is gone. If not you could go on and rotate all of the tires as RandomNerd2000 suggested and see if the noise and symptoms change sides and location.

 

[RandomNerd2000]

My old Goodyear Wrangler Radials I was really good to, and I had this literal thing on a near identical vehicle, and it was tires, I had a whole set of them, and they're just so bad about belts breaking and stuff poking random holes in them that I've never been so disappointed in anything more-so vehicle related. In the time I had mine, I had three flats (one I never found the leak), and the broken belt/whoop ordeal.

Pay careful attention, because mine that caused the whoop or roaring noise ended up having broken cords and the tread almost peeled off, without so much as a single vibration or anything, I just noticed a "growing" tire, I have pictures of it here still.

 

[GLOCKer]

I'm leaning towards tires as the culprit, bearings as a possibility.

 

[MAS Tequila]

Those Wranglers are crap.

The can look fine and do exactly what you're describing.

I had that issue with 2 sets of them.

 

[koda2000]

Those Wranglers are crap.

The can look fine and do exactly what you're describing.

I had that issue with 2 sets of them.

Worst tires I've ever had on a vehicle. I got rid of them almost immediately.

 

[Sal]

That's interesting that so many comments are directed towards the Wranglers as the culprit. That's what my 1st impressions were as well. Since I bought the road hazard warranty when I purchased these tires at Walmart (they're the 2nd set I put on), I had them rotate and rebalance all the tires.
The "whoop-whoop"didn't appear to move as did the tires.
I sort of concluded the tires were OK but from what's being expressed, I think I might start all over again and confirm whether the tires are at fault.

Again, I'm thinking to get the car on a lift and put it in gear. If the whoop is still there, it's probably not the tires since there isn't any load on them. On the other hand if the noise is gone I think we might be heading in the right direction.

 

[German Engineer]

Getting the car on a lift and putting it in gear is not a bad idea per se. But changing a tire is probably much quicker and cheaper to do though.
Also keep in mind that when you put the car on a lift, the entire suspension is relieved from load and will extend all the way down. That could also make noise originating from somewhere other than a tire disappear, if you're really unlucky.

And mentioning that now gives me the absolutely last other idea that I have, where a whoop noise could possibly originate from. You could also have a broken rubber drive axle boot.
But you would most likely have already noticed that right away and you would then likely also have a bad CV joint causing additional symptoms and noises.

But all talking and talking and talking of course won't really diagnose the problem by itself.

As mentioned, my first and best bet just like most others bet here is and remains the tires, especially the right front tire.
If you have a full size spare, then just change that out quickly and your symptoms will very likely be gone already.
And if that's happens to be the case then you can even just take the tire to a store and have them replace it right there and then.

PS:
You probably know, but just generally speaking for people who don't:
If you decide to replace just one single tire with a new one then make sure to get the exact same brand and type. Otherwise it's MUCH better to go right ahead and at least buy two identical tires and have them both mounted on the same axle, rear or front. Ideally you would of course want 4 identical tires. And from the drastic comments on your tire type here you might really want to plan on replacing your wrangler ones with some other brand or make sooner or later. If not all 4 at once, then replacing 2 of them now with a comparable tire of a different brand or make (I'd then use the good left over one as a spare) and then replace the other 2 later on when another tire fails is not a bad way for a cheaper route to, go unless you really plan on racing your truck on the Autobahn or try to win a Gumball of course.

 

[J_C]

Record it on your phone and post on youtube or elsewhere?

I'm doubting it's the tire since they were rotated, but if you need one new tire, you can't just buy same make a model tire, it's a start but the goal is to end up as near the same diameter as possible.

You can measure various new tire choices and have a tire shaved down to the same diameter as the other tires. It's typically around a $20 service, OR just get a used tire and take your tape measure with you so you can measure for a close match.

Have any of your suspension bushings been replaced with aftermarket polyurethane bushings? If so I would define a situation where you can consistently reproduce the noise, take a spray bottle with high concentration soapy water and spray them down, then see if the noise remains.