Purpose of cowl vent holes?

[cobramike33]

Going to have to address rusted out cowl vent holes, but my question is do they serve a function worth saving? Pardon if this question sounds foolish, but curious if welding them up and just utilizing the ac fan is a viable option.

[b5blue]

  With my Classic Auto A/C system the right side is blocked as part of the install. I pulled my left side vent box sometime ago and to get full effect from the new A/C blocked it off also. I think you'd be fine. I'm still testing but not missing having vents.

[cobramike33]

Thanks B5. It seems riskier to keep them open for potential future leakage and I do plan to run a vintage air system myself. It would be extremely frustrating to undue so I'm seeking advice from the been-there-done-that crew 

[green69rt]

One problem with permanently sealing them off is that stuff accumulates in the cowl.  My car was full of leaves and other debris when I got it.  I could reach up in a lot of the cowl and remove it by hand or with a vacuum hose.  If you permanently seal the vents you are pretty much blocked.  I know everyone says that they will protect their car but stuff happens so maybe a tight removable plug would be a possibility?  I can't imagine cleaning that stuff out more than one every year or three, but it might happen   

[b5blue]

He's talking about patching over the slots to make the cowl solid by the wipers, right cobra? Something many will deem "not right" but I'm considering myself.  In the past I've dealt with torrents of rain here in FL. that had me just pull over nearly in tears dealing with leaks.

[green69rt]

He's talking about patching over the slots to make the cowl solid by the wipers, right cobra? Something many will deem "not right" but I'm considering myself.  In the past I've dealt with torrents of rain here in FL. that had me just pull over nearly in tears dealing with leaks.

Oh, it that case....never mind.

[Dino]

If welding up the actual cowl slots is what you're talking about then you're going to have to make another vent somewhere or there will be no way to draw fresh air into the box. If it's in bad shape you can just cut the whole thing out and make sure the inside is in good shape with proper drainage on both sides. Then weld in a new cowl and be done with it. I drive mine in some pretty nasty rain and once I cleane dout the cowl and unplugged the drainage holes everything was just fine. Before that I found out I got wet feet!   

[b5blue]

The main reason I'm even thinking of it is you can't paint under the vent slots...I've tried and given up!  They just keep rusting back.

[Dino]

Nah, just block the drainage holes and vents and pour 7 gallons of paint in there.   

I think the only way to get paint there is to do it from below through the big ducts but that means stripping the interior. The other option is to spray the underside with a flexible nozzle through the slots but at that point I'd use a wax instead of paint. Either way it's a pita to get the underside covered.

[green69rt]

The main reason I'm even thinking of it is you can't paint under the vent slots...I've tried and given up!  They just keep rusting back.

Getting inside places on these car is tough.  I've used this stuff inside the trunk lid, hood, etc.  If you decide to use it, be careful.  It's really runny and will seep out any hole it can find.  If it does leak out use mineral spirits to clean it up.


http://www.eastwood.com/internal-frame-coating-w-spray-nozzle-qt.html

[b5blue]

  Yup tried that...found the flexible wand fits Rust Encapsulator cans also but controlling spray there is just no way. (Crap goes everywhere but intended.) Getting a coat on the inside of the upside down U shape of each vent rung can't be done. I had the entire vent system wide open and much of the dash apart.  Now on a rotisserie upside down you might get it coated someway? I just gave up! 

[Dino]

Lower lots of small paint bombs down the cowl and mask the vents shut before detonation! There! Insta-paint!   

[green69rt]

  Yup tried that...found the flexible wand fits Rust Encapsulator cans also but controlling spray there is just no way. (Crap goes everywhere but intended.) Getting a coat on the inside of the upside down U shape of each vent rung can't be done. I had the entire vent system wide open and much of the dash apart.  Now on a rotisserie upside down you might get it coated someway? I just gave up! 

Sounds like you had lots of fun!  Yes it's hard to control and it will go everywhere.  Don't have a solution for that except to clean up afterward.