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H3 Howling sound during acceleration - is this bad?

Z

Zerreitug

Active Member
Messages
29
Location
Tulsa, OK
Hey everyone, i have a 2006 H3 3.5L and I get this reasonably loud howling sound when I am pressing on the gas pedal. It sounds like it overlays the normal engine sound. It begins around 35mph, i have only taken it up to around 55mph and the sound is still present. If i let off the gas pedal, the howling sound stops completely. It will resume as soon as I press the gas pedal again.

My tire tread is semi aggressive but >75% tread life.

Anyone have this problem and found a solution to it, or is this sound normal. I ask because it can get pretty deafening and annoying.

Thanks for any help.
 
Z

Zerreitug

Active Member
Messages
29
Location
Tulsa, OK
Thanks for the reply Happy Hummer.
What information could i provide that could offer more insight? Im not very familiar with mechanics but I will do my best.
As far as the differentials, do you think this is just a symptom of normal wear? 185,000 miles.

I just changed the front differential fluid and aside from a small amount of the fluid having very very (very) fine metal dust, the majority of the oil looked okay(from the perspective of an inexperienced mechanic - me).

I was planning on running it for a few weeks and changing it again to compare the difference between the two oils.
Do you think that would be beneficial or just $$$ wasted?

Happy Hummer said:
In order to be of any help will probably need more information.

Howling could be associated with front or rear differential.
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J

JPaul

Well-Known Member
Messages
2,401
Location
Way up north, UT
Sure it's not the engine fan? When the clutch is engaged the fan is pretty darn loud. More of a roar than a howl though I guess. Have any audio of the sound?
 
alrock

alrock

El Diablo
Staff member
Messages
10,447
Location
Scottsdale
If you're getting that sound by using the accelerator, and it goes away when you are off the accelerator - can you get the H3 to make that sound when you are stopped? Try it in Park, try it in Neutral.
 
4speedfunk

4speedfunk

Well-Known Member
Messages
4,212
Location
Tardville
Throttle/coast noise is usually related to wear somewhere in the driveline. Check the front driveshaft first...there is a CV joint where it bolts to the transfer case, that can make horrendous noise when it goes bad. It’s cheap and easy. If that’s not it...I would check u-joints, then pinion bearings next.
You can remove the front driveshaft completely and put the t-case in 4Hi-lock mode. Go for a drive...this will tell you if the problem is in the front or rear driveline (and also allows you to inspect the CV on the front shaft).
 
Z

Zerreitug

Active Member
Messages
29
Location
Tulsa, OK
Thanks for the replies everyone. I really appreciate the help.

Jpaul & rascole -- I will get some audio of the H3 during my lunch today and post to youtube tonight. Thanks for the suggestions on that.
rascole said:
Try taking a video clip and post it to youtube.
Click to expand...

JPaul said:
Sure it's not the engine fan? When the clutch is engaged the fan is pretty darn loud. More of a roar than a howl though I guess. Have any audio of the sound?
Click to expand...



alrock -- I will try this test out today and post the results. Probably make a video of it also in an attempt to give more insight. Thanks for the suggestion.
alrock said:
If you're getting that sound by using the accelerator, and it goes away when you are off the accelerator - can you get the H3 to make that sound when you are stopped? Try it in Park, try it in Neutral.
Click to expand...


4speedfunk -- Thanks for the troubleshooting advice. I will investigate the driveshaft, transfer case and the CV joints this weekend (as well as google all of those to get more informed of their operation "noob mechanic")
4speedfunk said:
Throttle/coast noise is usually related to wear somewhere in the driveline. Check the front driveshaft first...there is a CV joint where it bolts to the transfer case, that can make horrendous noise when it goes bad. It’s cheap and easy. If that’s not it...I would check u-joints, then pinion bearings next.
You can remove the front driveshaft completely and put the t-case in 4Hi-lock mode. Go for a drive...this will tell you if the problem is in the front or rear driveline (and also allows you to inspect the CV on the front shaft).
Click to expand...
 
mdocod

mdocod

Well-Known Member
Messages
61
Location
Colorado Springs, Colorado
Sounds a lot like diff noise to me, but really could be anywhere along the driveline where gears mesh. Sounds like gears meshing badly to me.

Can you determine if its coming from the front/middle/rear of vehicle? Might be well worth having a passenger come along and compare noise levels in the far back to the front of the car.. rear diff sounds sometime propagate in the cab in ways that make them sound like they are coming from somewhere else unless you move around in there.

I'd be curious to try downshifting, see if you get the same noise or some new noise when under engine braking.
 
rascole

rascole

Well-Known Member
Messages
2,587
Location
Bellflower, CA
I can barely hear it but if I heard what I think sounds like TC chain noise. I can't stress enough how helpful a GoPro is in situations like these. Mount it as close to what you think is the problem is until you narrow it down.
 
Z

Zerreitug

Active Member
Messages
29
Location
Tulsa, OK
When i drive alone, it sounds like its coming from the front center slightly over towards the passenger side. Ill try to get my wife to hear it from different locations in the cabin to get some more data. That was an excellent suggestion mdocod. Thanks for the input. Ill try downshifting and check for changes also.
mdocod said:
Sounds a lot like diff noise to me, but really could be anywhere along the driveline where gears mesh. Sounds like gears meshing badly to me.

Can you determine if its coming from the front/middle/rear of vehicle? Might be well worth having a passenger come along and compare noise levels in the far back to the front of the car.. rear diff sounds sometime propagate in the cab in ways that make them sound like they are coming from somewhere else unless you move around in there.

I'd be curious to try downshifting, see if you get the same noise or some new noise when under engine braking.
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Yeah, sorry for the sound quality rascole. I swear it was more obvious listening directly from my phone, but even then, it is kinda hard to pick out. I would like to get some sound from highway speeds but my intelligence doesnt allow me to do that. Ill get my wife to record the sound on the highway the next opportunity i have.

The GoPro sounds like a good idea but its kinda pricey. Maybe a cheaper knockoff would work. It would also allow me to check 4speedfunk's suggestion with the CV joint that hooks up to the transfer case. The last time I was under the Hummer I did notice a small tear in a CV Boot.
Thanks for the advice rascole.
rascole said:
I can barely hear it but if I heard what I think sounds like TC chain noise. I can't stress enough how helpful a GoPro is in situations like these. Mount it as close to what you think is the problem is until you narrow it down.
Click to expand...
 
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Z

Zerreitug

Active Member
Messages
29
Location
Tulsa, OK
Here is an update for you mdocod. I drove the H3 until it started with the "howling", then downshifted as you suggested (only 1 position), but there was no change. It was identical to being in Drive. I feel like it has become quieter a bit. The only thing changed is me putting some miles on with the new differential fluid in the front. I dont have any data to back this up obviously but It seems to have quieted down a very small amount (im pretty sensitive to noises). Im gonna change the rear diff fluid this weekend and see how it looks.
mdocod said:
Sounds a lot like diff noise to me, but really could be anywhere along the driveline where gears mesh. Sounds like gears meshing badly to me.

Can you determine if its coming from the front/middle/rear of vehicle? Might be well worth having a passenger come along and compare noise levels in the far back to the front of the car.. rear diff sounds sometime propagate in the cab in ways that make them sound like they are coming from somewhere else unless you move around in there.

I'd be curious to try downshifting, see if you get the same noise or some new noise when under engine braking.
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Thanks for the suggestion Clark, are you referring to the wheel hub bearings? Sorry if it seems obvious but im new to auto mechanics.
Clark said:
Badly worn hub bearings can make a loud howling noise. Like you described. you can start there. Good Luck
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Clark

Clark

Well-Known Member
Messages
153
Location
New York
Zerreitug said:
Here is an update for you mdocod. I drove the H3 until it started with the "howling", then downshifted as you suggested (only 1 position), but there was no change. It was identical to being in Drive. I feel like it has become quieter a bit. The only thing changed is me putting some miles on with the new differential fluid in the front. I dont have any data to back this up obviously but It seems to have quieted down a very small amount (im pretty sensitive to noises). Im gonna change the rear diff fluid this weekend and see how it looks.


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Thanks for the suggestion Clark, are you referring to the wheel hub bearings? Sorry if it seems obvious but im new to auto mechanics.

Yes badly worn hub bearings will create a loud humming noise while in drive. It feels like your running without any lubrication.
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cgalpha08

cgalpha08

"Like Nothing Else"
Messages
3,585
Location
Indianapolis, IN
I would do as some others have suggested. I had a similar noise, turned out to be my front pinion bearing.

1. block off the wheels so the H3 doesn't roll
2. put the transfer case into 4 hi lock
3. remove the front driveshaft, its 8 bolts total, 4 at the transfer case, 4 at the front diff.
4. go for a drive.
* the h3 has to be in 4 Hi lock in order to drive with the front driveshaft removed*

If the sound is gone, then its an issue in your front axle assembly and you'll probably need to pull the front diff and investigate.
If the sound is still there, its in one of the remaining moving parts...trans, t-case, rear axle.

Check the driveshaft while you're under there, the boot does rip letting all the grease out and then the bearings go bad, but IIRC this makes more of a clicky sound than a howling (happened to me once).

Removing the front driveshaft is an easy and quick way to help narrow down where the problem is.
 
Z

Zerreitug

Active Member
Messages
29
Location
Tulsa, OK
Thanks cgalpha08. Those sound like some solid troubleshooting steps i can do. Ill look into removing the front driveshaft and checking the boots as well.

Thanks to everyone giving suggestions and sharing your experience to help me with this problem. I really appreciate it. I will be looking into your suggestions and try to figure this out.

cgalpha08 said:
I would do as some others have suggested. I had a similar noise, turned out to be my front pinion bearing.

1. block off the wheels so the H3 doesn't roll
2. put the transfer case into 4 hi lock
3. remove the front driveshaft, its 8 bolts total, 4 at the transfer case, 4 at the front diff.
4. go for a drive.
* the h3 has to be in 4 Hi lock in order to drive with the front driveshaft removed*

If the sound is gone, then its an issue in your front axle assembly and you'll probably need to pull the front diff and investigate.
If the sound is still there, its in one of the remaining moving parts...trans, t-case, rear axle.

Check the driveshaft while you're under there, the boot does rip letting all the grease out and then the bearings go bad, but IIRC this makes more of a clicky sound than a howling (happened to me once).

Removing the front driveshaft is an easy and quick way to help narrow down where the problem is.
Click to expand...
 
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crwalkerasla

crwalkerasla

Well-Known Member
Messages
313
Location
Corinth, MS
I would like to thank everyone in this string. On the return leg of a 3K mile trip, my '06H3 started doing the exact same thing. I got to looking it over and the rear seal of the TCase had been leaking. By the time I was able to find a truck stop with a garage open on Sunday morning, the whine, turned to a howl, to roaring like a banshee. A jug of LUCAS & ATF tempered the sound until I had to stop for gas. The roar returned, but I was able to get back home.

Check your seals before the real damage is done.
 
crwalkerasla

crwalkerasla

Well-Known Member
Messages
313
Location
Corinth, MS
Also, 2 more things.
1. The '06, '07, & '08 each used a different fluid in the TCase. '06 used Dexron III-H which is no longer sold. The substitute is D/M ATF.
2. The TCase on the '06H3 cannot be filled to capacity from the fill plug. You need to remove the speed sensor just above the plug and fill it there.
Hope this helps.
 
mdocod

mdocod

Well-Known Member
Messages
61
Location
Colorado Springs, Colorado
Lol... the T-case fluid can of worms...

I'm of the opinion that any of the Tcases from any of those years will run fine on just about any ATF-like fluid, as long as they are filled to the proper level, and that there may be advantages in this application to selecting thicker and/or synthetic ATF options from premium brands like Redline/Amsoil.

The most likely reason for them to transition from speccing the Dex III to the Dex VI is the reduced viscosity of Dex VI is apt to improve average fleet fuel economy estimates.

I'm very tempted to treat the ATF I put in there recently as a flush... dump it and put some thicker fluid in there for when I put up the skid plates, which will likely make the tcase run hotter.
 
Z

Zerreitug

Active Member
Messages
29
Location
Tulsa, OK
Just wanted to thank everyone involved in this thread giving me advice & here is an update as to the status of my howling source. My wheel bearings are fine and my front differential seems to not be the problem.

I believe the howling is coming from a vacuum leak somewhere in the system. Im suspecting a connection point from the throttle body but I am still investigating. I also notice my brakes make a kind of "squish" when i press the pedal down, so I am going to look into master cylinder troubleshooting and checking o-rings.

I changed my focus from mechanical because the howling, which I thought was constant, was absent from my driving occasionally, but then revealed itself intermittently during the same driving conditions. Also it completely disappears @ 60+mph. That scenario combined with the brake "squish" sound when pressed leads me to think there is a vacuum leak at a connection point big enough to cause a howl during the 40-59mph range. Also it sounds pretty much inline with the throttle body from the cabin.

Anyways just wanted to update you all and thank you for the advice. If you have more insight, ill gladly accept it, along with some good luck wishes.
 
A

atvspeed4

Well-Known Member
Messages
1,173
Location
massachusetts
JPaul said:
Didn't all of the H3's have electronically assisted power brakes and not vacuum assisted?

Sent from my SM-N950U using Tapatalk
Click to expand...

Correct, all H3 do NOT have vacuum assisted brakes. They have a small electric pump and accumulator. H3 also do not use vacuum to control HVAC.

For what its worth all of our H3s (5 of them) have that annoying howling noise you are discussing. They all have over 150k miles on them and despite throwing wheel bearings, driveshafts, CV shafts, T-case chains etc they each still make various levels of the same noise over 60mph under load. I think our next step will be a full transfercase rebuild to swap out all bearings and see if that helps.
 
Z

Zerreitug

Active Member
Messages
29
Location
Tulsa, OK
atvspeed4, thanks for hitting me with that knowledge. Its always good to learn more about my hummer. Keep me updated if the transfer case rebuild fixes that problem. I appreciate the info.

atvspeed4 said:
Correct, all H3 do NOT have vacuum assisted brakes. They have a small electric pump and accumulator. H3 also do not use vacuum to control HVAC.

For what its worth all of our H3s (5 of them) have that annoying howling noise you are discussing. They all have over 150k miles on them and despite throwing wheel bearings, driveshafts, CV shafts, T-case chains etc they each still make various levels of the same noise over 60mph under load. I think our next step will be a full transfercase rebuild to swap out all bearings and see if that helps.
Click to expand...
 
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