Cowl fresh air venting

[66furys]

I have been chastised for silly questions, but have another. I am fighting the water intrusion from the cowl that rusted my driver side floor, and will now pull the kick panels to install carpet. I have not yet pulled the cowl, and am wondering how the huge amount of leaves get into the vent system at the lower doors. New vehicles have screens to prevent entry, and am assuming that these cars just have large openings, and any leaves that migrate thru the cowl louvers just come in thru a large vent hole. I am assuming that I may want to add some type of screen to prevent this.....when I later pull the cowl. Cannot attack everything at once, and am just thinking about this for now, as I pull the panels below. Just wondering what others have done about this. thanks

 

[73Coupe]

Suggest to pull the cowl vent screen and the kick panel vents, pull the front carpet, vacuum it out then flush out with a high pressure hose spray. Make sure the drain holes at the bottom are cleared.

This is a commonly neglected area - out of sight, out of mind...until problems arise. Never painted, hard to clean, and a perfect receptacle for dirt and organic debris....optimum conditions for decay.

 

[1971 300 Alvah]

For my '71, I would have a flood of water come in through the lower vent. There is a rubber flapper at the bottom of the cowl that is there to let water drain out, but it was obscured by decades of debris. I cleaned it out and have not had any water enter since. This is serviced from the engine side of the firewall.

 

[66furys]

thanks both for the help....appreciate it.

 

[MoPar~Man]

What can you do, if you're here, and you want to make these areas less prone to material build up, prevent rusting, etc? I still don't get how and where water flows/drains through these side passages but allows fresh air to enter through the kick panel vents.

 

['66 Fury I]

I agree with cleaning, opening drains and flushing. However every time the car is washed or out in the rain, the cowel is flooded and will remain wet, especially in the crevases, for who knows how long. This is ideal conditions for rust. I've wondered if anyone has thought of spraying, fogging or pouring something to prevent or neutralize rust. Anything used would have to dry "non-sticky" and penetrate exsisting rust and debris.
How about it, any ideas? Thanks! Lindsay

 

[1971 300 Alvah]

Here's how the water stays out. The lowest portion of the cowl has this little rubber flapper valve (red arrow) that lets water drain out (normally), the air inlet for the cowl vents is above this, so water should all drain out and not get into the vents. When the drain gets clogged, water backs up until it can flow down into the vents. I used a hanger to "open up" the drain and then flushed it out really well with water. This was probably 5 plus years ago and I haven't had the issue reoccur since. Car is kept outside all the time.

 

[73Coupe]

Here's how the water stays out. The lowest portion of the cowl has this little rubber flapper valve (red arrow) that lets water drain out (normally), the air inlet for the cowl vents is above this, so water should all drain out and not get into the vents. When the drain gets clogged, water backs up until it can flow down into the vents. I used a hanger to "open up" the drain and then flushed it out really well with water. This was probably 5 plus years ago and I haven't had the issue reoccur since. Car is kept outside all the time.

View attachment 644332

At least on a fuselage body, a poor design in my opinion. However if this gets clogged the water will flow horizontally and drain out the sides and exit via the lower cowl drains, located behind the kick panels/rear of fenders. Not sure what year car the OP has or how the other eras are different. But important to keep this clean in addition to the lower sides of the cowl where debris also becomes lodged and blocks the drains.

 

[D Cluley]

I added a layer of black window screen under the cowl vents. It is practically invisible, and I figure anything small enough to get through the holes in the screen will flush right out the other end.

 

[buicker]

I've had water entering from vent and geting the carpet wetWas cause by rust holes on cowl, afer fixing, it still was leaking, fond out by having water running in cowl and with a mirror looking up true the vent I saw water comming in from the tin joint insinde the vent

 

[SuperDave]

Pine needles are the worst! They can and do get thru the cowl screens and are highly acidic, as they break down they greatly contribute to rust. That's why you don't see green turf grass under pines, the soil is too acidic from all the fallen needles.

My answer is either park indoors or a car cover. Getting them out requires pulling the heater box assembly and vacuuming it out with a hose. Big job. I have considered painting the inside of the cowl compartment with bed liner paint if I want my car to last another 50 years. A rusted out cowl box would dramatically impact the structural integrity of a unibody vehicle.

 

[Just Carbs]

If the car will be outside in the weather, I put magnetic sign sheets cut to fit over the cowl.

 

[66furys]

The cowl bowl is divided into three regions; the center has a crevice below the wiper motor that you can easily get something into, to clean to the flap hole in the firewall. But, both sides drain into the vent region that is a large cave behind the vent doors. There are small indents that you can feel with a finger from the top, and you can see them at bottom below the fender...pretty good size. After you clean out the vent caves after removing the vent housings, you can run water from the top and clearly see it drain into these caves and will exit below.....ends all questions. I could not get any kind of brush in there, so washed with rags and cleaners, then with paint prep, and finally used etching primer and then paint inside. I am now a happy camper with this mess. I am not at all happy now that I was faced with a wiper motor with no connector link. For only two years they used this specific park mechanism that is unobtainium. I am off to the salvage yard when I can get there after removing my variable motor. Not happy about this one.