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Discussion Starter · #1 ·
All,

This may apply primarily to us truck owners, but some vehicles have interior vents or cab vents that allow for proper A/C flow and pressure equalization inside the vehicle. On my Ford pickup, two of these devices sit on the back wall and have thin one-way flaps that allow pressure out of the cab:



Unfortunately, these have caused me two problems:
  • One needed to be removed to allow for subwoofer installation.
  • The remaining one opens when the subwoofer hits (air movement) and makes a buzzing noise worse than any panel rattle I've ever heard.

What creative ways have other managed to silence these? Presumably they are there for a reason, so I'm reluctant to take them out altogether. Plus, I've not actually found a neat way to seal them off (currently have a layer of Dynamat over the opening left by the one, but it's not really elegant as the adhesive back side is picking up all the dirt that falls between the bed and the cab).

Any suggestions appreciated.

Thanks!
 

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maybe a layer or 2 of ensolite? I dont have any of those...

I'd try covering it completely, and if the cabin pressure is not to your liking the find a way to keep them from moving at all.
 

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Whatever you do....do NOT remove the vent. I belong to another forum and have written about my experience after removing them.....

Dont touch your cabin vents! - F150online Forums

Some people have covered one vent with sound mat like Damplifier Pro. You could also apply an air filter or other material over one or both vents to allow air to pass but absorb sound waves?
 

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Cheap fix, shread some cotton balls and use spray adhesive to attach them. It allows the air to move through, but muffles the sound. Worked good for me.
 

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Discussion Starter · #5 ·
Whatever you do....do NOT remove the vent. I belong to another forum and have written about my experience after removing them.....

Dont touch your cabin vents! - F150online Forums

Some people have covered one vent with sound mat like Damplifier Pro. You could also apply an air filter or other material over one or both vents to allow air to pass but absorb sound waves?
Thanks for the link, I did take a look. I *think* I could get mine back in if I had to (the way they came out required some manipulation when they were between the cab and bed. But not worth the effort since I'm still convinced having one is a requirement for good pressure equalization in the cab. Since the one had to be removed, I still need to find a better way to seal it and I saw your notes about proper flashing. I'd like to think a rectangular piece of plastic over the hole, siliconed on the inside, then covered with a buytl Dynamat-like product on the inside should work. Right now I think the single layer of Dynamat I have over it is keeping it weather-tight, it's just not an elegant solution.
 

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Discussion Starter · #6 ·
Cheap fix, shread some cotton balls and use spray adhesive to attach them. It allows the air to move through, but muffles the sound. Worked good for me.
Thanks. I may try a piece of foam air filter attached to the inside with adhesive as a possibility.

It's such a pain to get back there that I only want to do this once...

It's funny to watch the flaps bounce open when the subwoofer plays. The buzz they generate is unreal.
 

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Right now I think the single layer of Dynamat I have over it is keeping it weather-tight, it's just not an elegant solution.

I think you might be under a wrong impression. The entire article that I linked you to is about me relying on sound mat to keep water out. That lasted about 2 weeks.

Considering how little room one has to work with between the bed and cab, I have my doubts that proper flashing can be accomplished with the vent out.

I was convinced I could do it....now I am convinced I could not do it. Hence the reason I put the OEM vents back into place.

I wish you luck.
 

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Discussion Starter · #8 ·
I think you might be under a wrong impression. The entire article that I linked you to is about me relying on sound mat to keep water out. That lasted about 2 weeks.

Considering how little room one has to work with between the bed and cab, I have my doubts that proper flashing can be accomplished with the vent out.

I was convinced I could do it....now I am convinced I could not do it. Hence the reason I put the OEM vents back into place.

I wish you luck.
Probably right. I've had the mat in place for a year and have not noticed any leaks as I've checked the back panel and floor in the area. But it may only be a matter of time before it starts. Granted, the truck is not a daily driver, but it does sit through all rainstorms, so I'd like to find some way to make it work.

I guess I'm still searching for a better way to seal the one off...
 

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Discussion Starter · #9 ·
I think you might be under a wrong impression. The entire article that I linked you to is about me relying on sound mat to keep water out. That lasted about 2 weeks.

Considering how little room one has to work with between the bed and cab, I have my doubts that proper flashing can be accomplished with the vent out.

I was convinced I could do it....now I am convinced I could not do it. Hence the reason I put the OEM vents back into place.

I wish you luck.
Did you have anything on the back side (outside) of the deadener? I think I may have asked you this in your build thread, not sure...
 

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In my truck I trimmed off the bottom cup portion to make the vents more of a uniform bump in the wall. Then I used strips of 3/4" to space my amp board off the back wall and around the vents. I have removed the amp rack a few times to check for moisture and such as it was a concern but I have yet to find any signs of it on the raw MDF that is near the vents.

I was planning on covering them up but figured if I could work around them it would be all the better. I would think something like ensolite or overkill or luxury liner over them would quiet them up.
 

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Did you have anything on the back side (outside) of the deadener? I think I may have asked you this in your build thread, not sure...
No, I did not. But I did put a second layer of deadener face to face with a piece in the inside (custom cut to fit the hole exactly) so that the water woudl not cause the deadener to peel away. The deadener stayed put....but the water came into the cab anyway.
 

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In my truck I trimmed off the bottom cup portion to make the vents more of a uniform bump in the wall. Then I used strips of 3/4" to space my amp board off the back wall and around the vents. I have removed the amp rack a few times to check for moisture and such as it was a concern but I have yet to find any signs of it on the raw MDF that is near the vents.

I was planning on covering them up but figured if I could work around them it would be all the better. I would think something like ensolite or overkill or luxury liner over them would quiet them up.
Thats good to know. I assumed the cups were there to prevent water, which was forced into the cabin via the vents, from spilling into the cab (essentially creating a dam and forcing the water to drain back out). So cutting them off did not seem like a good idea. However, I did have to cut mine off when I purchased new vents and inserted them from between the bed and cab. It was the only way I could get them between the bed and cab before pushing them into place.
 

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Discussion Starter · #13 ·
I'm going to go with re-sealing the one with Dynamat (the single layer of Dynamat I had over the hole lasted for a year with no evidence of moisture entry) in a slightly improved fashion.

For the one that remains, I am going to double-layer a bedsheet over it to reduce the airflow and muffle sound (as suggested in one of the forums I was reading).

I'll post back with results and pictures.
 

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Discussion Starter · #14 ·
FIRST, how I (hopefully) silenced the flapping from the one remaining cab vent.

This is the one on the passenger side, not obstructed by my sub. It buzzes like crazy when the air moves through it when the bass hits.



Just some fabric (bedsheet) folded over and buried in the sound deadener. Hopefully enough to slow the velocity of the air just enough and to insulate some of the sound.
 

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Discussion Starter · #15 ·
NEXT, my approach for completely sealing the other cab vent, the one that sits behind the sub. I previously had one layer of deadener over it and it sealed fine for a year (when I took it off today, it was completely dry and no evidence of water coming through).

Since it seemed to work previously, I got an idea for a modified solution today.

Cut out some ABS to fit just inside the opening:



Attached it to some deadener:



"Inserted" it in to the opening (about 1/16" gap on each side):



Sealed it up:



Hopefully the butyl has sealed the edge as it did previously and the ABS on the outside will not attract the dust, dirt, and leaves like my previous attempt.

Not perfect, but the best I could come up with.
 
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