Painful low frequency drone/pressure in cabin

[LJE]

Low frequency vibrations could be absorbed my body mounts, but the sound transfers.

Another thought is pull your radio fuse and see if something is interfering with the H/U?

I’m totally spitballing. I can make my speakers buzz by setting my JBL amp to the wrong speaker OHM.

Electrical interference sounds like a plausible rabbit to chase... I've had weird ground issues in another vehicle that led to a buzz through the speakers that corresponded with engine RPM...

I had a seemingly similar issue with air pressure when we were driving through Colorado/New Mexico last month when there were some high crosswinds. It felt like the outside air pressure was creating a vacuum and pulling the driver's side door away from the body enough that it broke the seal on the door weatherstrip (about to replace it on both front doors), and every time it would lose that seal we'd get a weird drone that reverberated in the cabin like when you have a window cracked or open just wrong.

If the drone is more or less constant, it sounds less likely that this is your exact issue, but the weatherstrip rubber on the doors might be something to at least inspect.

I don't think the little subwoofer in the back would be able to move enough air to cause this leave of ear pain, haha. But, I'll give it a look again. I'd also expect it to be present at all speeds (and not get worse at higher speeds) though.

Door seals are at the very least there, but I'll give them a more thorough look. May try painters tape around the doors seams to try and diagnose as well.
When this happened to you, could you audibly hear a hissing noise? Or just the resonating drone? (apparently having a single window open makes the car into a Helmholtz resonator). I don't hear a hissing noise from air sneaking in, but the effect on my eardrums is very similar to having a single window open at speed.

I also need to check the headliner I think - it's a giant piece of material, so I could see it vibrating just the right (wrong?) way and pushing enough air to cause this issue.

 

[jaewastooshort]

could you audibly hear a hissing noise? Or just the resonating drone? (apparently having a single window open makes the car into a Helmholtz resonator). I don't hear a hissing noise from air sneaking in, but the effect on my eardrums is very similar to having a single window open at speed.

There was so much wind outside the car it's difficult to say what air noise was internal vs external, just that when the door seal was compromised it was quite uncomfortable with the buffeting sound. Old seals don't have as much spring and are easier to break, which is what I think caused my issue, and hoping that fresh seals will do a bit better. If you have one that's bad enough it's always leaking somewhere, seems possible that air speed while traveling is creating a weird air issue.

 

[GerLC100]

Beside sealing the doors/ check the weatherstrip: how sure are you that all windows are properly closed/ sealing? Sun roof slightly open/ not sealing? rear vent windows properly closing?

 

[Rhetoric]

I've been pondering this as I drive my truck around...

Is your windshield install good to go? As in: the windshield itself sealed properly? Trim installed using correct rivets? Something wonky there usually leads to more of a whistling sound, but maybe yours has a pressure response instead?

Have you checked if your C pillar exterior vents are working correctly?

I love a good puzzle so I hope the brain trust here can help get this solved.

 

[LJE]

I've been pondering this as I drive my truck around...

Is your windshield install good to go? As in: the windshield itself sealed properly? Trim installed using correct rivets? Something wonky there usually leads to more of a whistling sound, but maybe yours has a pressure response instead?

Have you checked if your C pillar exterior vents are working correctly?

I love a good puzzle so I hope the brain trust here can help get this solved.

I *think* its a factory windshield (at the very least, its OEM glass). Its got a spider web crack from before i got it, so its on the docket to get replaced anyways - the thought had crossed my mind.

Rear C pillar pressure vents seem to be functional - you can feel air blowing out of them with the AC cranked.

 

[Live to Ski]

good call on the c-pillar vents. that never crossed my mind.

 

[LJE]

Ugh. Another evening of troubleshooting, but no solution.

Things I tried tonight:

1. Taping all window trim
2. Making sure headliner wasn't vibrating
3. Making sure rear hatch wasn't vibrating
4. Trying different window open/shut combos. Opening windows helps some, but doesn't solve the issue.

Pressure resonance is worst between 55-62ish, seems to go away at above 70 (havent tested high speeds sustained though). Bumpy roads make it worse for sure at lower speeds.

I'm back to wondering about these tires of unknown history (beyond them being 4 years old, but lots of tread left). I think I'm going to try to find somewhere to roadforce balance the tires. It just seems odd that the actual resonance frequency seems wheel speed independent - amplitude definitely changes with wheel speed though. Wish there were someone around here with some spare wheels/tires to try out!

 

[RapidRob]

Ugh. Another evening of troubleshooting, but no solution.

Things I tried tonight:

1. Taping all window trim
2. Making sure headliner wasn't vibrating
3. Making sure rear hatch wasn't vibrating
4. Trying different window open/shut combos. Opening windows helps some, but doesn't solve the issue.

Pressure resonance is worst between 55-62ish, seems to go away at above 70 (havent tested high speeds sustained though). Bumpy roads make it worse for sure at lower speeds.

I'm back to wondering about these tires of unknown history (beyond them being 4 years old, but lots of tread left). I think I'm going to try to find somewhere to roadforce balance the tires. It just seems odd that the actual resonance frequency seems wheel speed independent - amplitude definitely changes with wheel speed though. Wish there were someone around here with some spare wheels/tires to try out!

I know,I know. It just doesn't seem like it's the tires but I think I would take the time to carefully inspect each wheel/tire assembly for out of round, bubbles
etc. As you said it would be great to borrow a set for a drive to totally eliminate that from your possibilities.
And don't discount the frame weight suggestion.
I also am interested to find out the solution to this mystery. Good Luck.

 

[MongooseGA]

How are your engine and transmission mounts? Diff mount bushings?

Is there any part on your exhaust that contacts the frame or the body?

 

[LJE]

How are your engine and transmission mounts? Diff mount bushings?

Is there any part on your exhaust that contacts the frame or the body?

All bushings/mounts (short of the cab mount bushings) are sll brand new. I even have new cab mounts, but that's a lot of work. Hahaha.

I planned on checking exhaust today - I'll report back on that.

 

[LJE]

I know,I know. It just doesn't seem like it's the tires but I think I would take the time to carefully inspect each wheel/tire assembly for out of round, bubbles
etc. As you said it would be great to borrow a set for a drive to totally eliminate that from your possibilities.
And don't discount the frame weight suggestion.
I also am interested to find out the solution to this mystery. Good Luck.

Visually the tires look fine (and spin up fine on a 'normal' balancer), but that's not to say that there's not a issue once load is applied to them. Going to try to get them roadforce balanced today.

 

[LJE]

Sigh. Another day and $100 in road force balancing later, still no fix or improvement.

I guess my next step is to pressurize the exhaust via the tailpipe and check for weird leaks - again, I would think that would have an engine-speed dependent part to it (and be more auible outside of the vehicle), but I'm fresh out of ideas here.

I somehow seem to have made a rather expensive torture chamber - driving the LX for more than 15 minutes or so leaves your ears hurting for the rest of the day...

 

[shane431]

Maybe the problem needs a new set of eyes (ears) to help diagnose. Got any trusty Cruiser shops in your area to take a look? It might at least give you some others ideas on where to look.

 

[leveeguy]

Someone send this man a frame weight just to rule it out if nothing else...

 

[Bisho]

May try pulling the fuse for your radio to rule out something going on with the audio system.

 

[LJE]

Maybe the problem needs a new set of eyes (ears) to help diagnose. Got any trusty Cruiser shops in your area to take a look? It might at least give you some others ideas on where to look.

Not a terrible idea, but I'm not aware of any in the south-central Indiana area. I do want to get a second person to drive while I move around

Someone send this man a frame weight just to rule it out if nothing else...

Hahaha. I'd try it out if someone had one! I cant believe they're $350... I did try clamping a decent size chunk of flat rock to my frame (lol), no change...

May try pulling the fuse for your radio to rule out something going on with the audio system.

I'll give it a shot, but i cant imagine the stereo system habing enough oomph to cause this sort of thing.

 

[AARONTLC]

Alright, have another odd one for the forum...

I just got Lazarus (2005 LX) back from the alignment shop - so it's the first time I've actually really been able to drive it ever! Super excited about that. Mechanically drives like a dream & all is well on that front.

However, above about 40 miles per hour I get a super low frequency 'drone' in the cabin. You can barely hear it, but holy crap does it make my ears hurt - feels like it's building pressure on my eardrums. If I'm going down a decent hill (i.e, no load on the engine) it goes away even at speed. I can rev the engine at a stop and it doesn't do it - seems like it has to be under load.

I do have Doug Thorley headers on it, but I've near heard of anyone having this issue with them.

Opening the rear quarter windows helps a little, but not much.

Has anyone had an exhaust leak somewhere cause something like this? That's my best guess - some sort of odd leak that's causing low freq pressure spikes. Open to other ideas though - it's a weird problem!

I have been following this thread for a couple days and I did some searching on other vehicle make forums. I stumbled across a problem that Mercedes Benz Sprinter owners deal with quite often and it has to do with the roof slightly separating from the support ribs. I am fairly certain what you are experiencing is low frequency vibration which feels like someone is slapping both of your ears at the same time. They identified it by sitting in the cab and then someone getting on the roof or really anywhere on the vehicle and with an open palm lightly slapping the body. Once identified they were able to find the separation and stuff rags or 3M mastic tape in the gap to stop it. I am not saying this is your problem but it may be worth checking. Good luck!

 

[MongooseGA]

Maybe I missed this, but were the headers installed before or during your ownership? Has any other exhaust work been done from the headers back?

 

[Zuberg]

I have been following this thread for a couple days and I did some searching on other vehicle make forums. I stumbled across a problem that Mercedes Benz Sprinter owners deal with quite often and it has to do with the roof slightly separating from the support ribs. I am fairly certain what you are experiencing is low frequency vibration which feels like someone is slapping both of your ears at the same time. They identified it by sitting in the cab and then someone getting on the roof or really anywhere on the vehicle and with an open palm lightly slapping the body. Once identified they were able to find the separation and stuff rags or 3M mastic tape in the gap to stop it. I am not saying this is your problem but it may be worth checking. Good luck!

Been following this thread and this is a great idea to check the roof AND hood. On my 2006 both the roof and the hood sheet metal had delaminated from the support structure. I had strange wind noise due to this.

I re-glued the hood and roof to the support structure and voila, silent once again.

If you tap on the hood and roof sheet metal it will be very evident if they have come free from the support.

 

[LJE]

I have been following this thread for a couple days and I did some searching on other vehicle make forums. I stumbled across a problem that Mercedes Benz Sprinter owners deal with quite often and it has to do with the roof slightly separating from the support ribs. I am fairly certain what you are experiencing is low frequency vibration which feels like someone is slapping both of your ears at the same time. They identified it by sitting in the cab and then someone getting on the roof or really anywhere on the vehicle and with an open palm lightly slapping the body. Once identified they were able to find the separation and stuff rags or 3M mastic tape in the gap to stop it. I am not saying this is your problem but it may be worth checking. Good luck!

That's a brillant idea! I've been scouring the web and hadn't found that. The wife and I just did this. Both the rear hatch and the roof seem like plausible areas. I'm pretty sure I've ruled out the rear hatch (put a ratchet strap on the interior panel to hold it all tight), but I think I may end up dropping the headliner.

Can someone smack their roof (lightly) for me and let me know how much vibration they see up by the sunroof? I've got a decent amount, but I'm not sure if thats normal since theres not much room for ribbing there.

Maybe I missed this, but were the headers installed before or during your ownership? Has any other exhaust work been done from the headers back?

I installed them when I replaced the engine when I bought/restored this LX, so I never ran it with the stock manifolds. No other exhaust work has been done.

Been following this thread and this is a great idea to check the roof AND hood. On my 2006 both the roof and the hood sheet metal had delaminated from the support structure. I had strange wind noise due to this.

I re-glued the hood and roof to the support structure and voila, silent once again.

If you tap on the hood and roof sheet metal it will be very evident if they have come free from the support.

Oooo good to know! I adjusted the hood bumper stops, but i did notice some noise when the wife tapped the hood as well. I'll look at the supports!