The vents are for pressure relief from blower fan use or the doors closing... but they tend to relieve pressure both ways, despite being one way flaps.

When the truck is barreling down the road at 60 mph, the local pressure from the frontal area pushing forward creates a slight local vacuum behind the vehicle.

This phenomena is why the backs of SUV's are so dirty, without an upper air deflector to direct some of the surrounding pressure to create a wind wash to counteract the vacuum.





I suspect that a slight vacuum is created in the space between the cab and the bed, and when driving in a driving rain, some water is sucked in through the gaps and cracks and flaps of the cab vents... toward the lower local pressure inside the cab, if the blower motor is off.

So even little rain hats over each cab vent may not be entirely effective at excluding water from entering. But they will certainly help.

I have purchased "hats" for this purpose... a rain guard for the entire rear window, and individual rain guards for each cab vent. I have not installed them yet, because to do so most effectively will require bed removal, and I am putting that off until I can coordinate other projects.

While I don't think the hats will entirely deny water penetration, for the reason already stated, I do think that the less water that penetrates, the easier it is for evaporation to manage what does make it past that very poor cab vent design.

 

If you are the designer, you have to have the parts in hand. Pull the rear C pillar interior trim, and remove the back trim card that covers the rear cab sheet metal. You may be inspired by what you physically see in a more informed way than anything you read. You have to see it with your own eyes and feel it with your own hands. We'll wait for ya.

 

I have seen mine, and seen that they have let some water trickle in (which is now frozen solid) from not the vents themselves but from the outside of the top corner due to the deteriorated foam seal. I have not had a chance to have both of them in hand to really look over and drum up a design, the newer style wont be a problem to get but I cant say the same about the older (99-02/ my) style, especially with them being obsolete and having to unbolt the box to remove one.

 

I sealed the top vent completely closed with JB Weld 15 second glue and a Plastic cut from a storage container.

Rain still gets in on both top corners of the hatch opening, even when the truck is sitting still all night, I have learned to never leave anything where it can get wet.

on the last 2 trips, I laid a thick Canvas Tarp over everything, and tucked it tight to the back edge of the door.

 

So the moral of the story is to leave your a/c blower on high speed?

 

The old style vents can be removed and remounted without having to remove the bed box.

Once the back trim panel inside the cab is removed, the old vents can be squeezed gently, such that the one way tabs on the top are depressed, one at a time, and pushed outside of the sheet metal hole, while still hanging on to the vent frame.

Continue doing the same for each one way tab around the vent perimeter, until the vent is released from the back panel, and is precariously held by the center ribs. Rotate the vent 90°, lower, and tip the vent now vertically oriented back into the cab as a freed part.

 

I had to remove my bed box to get the vents out. However the front of the box was somewhat bowed toward the cab which limited the amount of space I had to work with.

Would have saved me multiple hours and some scraped up knuckles.

 

Ever get around to scanning the vents?

 

I of course had the leaky year cab vents in my 2003 f350.. the thread gave me some ideas in addition to bringing me aware that the vents aren't available anymore.. I didn't particularly want to replace them any how since they are very hard to remove from inside the cabin.. I didn't really feel like removing the bed..

So I made the following with things I had in the garage a 12 dollar sheet of thin gauged after metal from home depot and some marine vent covers I got on 9 dollars on Amazon.

I cut the sheet metal down with aviation snips, and sized it so that it would over lap the vent opening by an inch on all sides. . I installed the vent covers in the middle of the sheet metal with silicone and screws that I angle grinned down. I drilled two 3/4 inch holes for the venting. Then I got two strips screen ac folded them and placed them on the other side of the sheet metal compared to the marine vent covers and used super glue to put the screening in place. .

I had some sound proofing laying around and used spray adhesive to attach to the sheet for the inside of the truck.. I don't think you need that.. it was just an extra step..

I then caked a liberal about of silicone immediately around the open area and then on the permiter of that a consistent beed of liquid nails.. I carefully put it in place and stacked some weight on it over night..

Did the garden hose test the next day, not leaking at all. .

I think it's a little over kill.. but I hate water instrusion..

By the way.. I think this is only an exchange vent.. only equalizes pressure or air exchange.. as long as there are holes in the cabin that are protected from insects and is water intrusion proof, that's all you're looking for. You could cap it off if you always planed to have a window cracked. .

Good luck..

 

I have a 2000 F350 which I purchased new. I have been giving it much needed "love" over the course of the last year. One thing I wanted to do was add subwoofer behind the rear seat. I had noticed water under the rear door sill and thought it was due to old door gaskets. Long story short, my vents had been leaking for a long time.

Initially, I thought about pulling the old ones and adding louvered vents to the area. My plan was to rivet/seam seal them in. I bought a louvered piece that is used on gas firepits for venting off of amazon. They were 15" long by 4.5" tall. Cutting it in half yielded 2 pieces which sit perfectly in the recessed area. I really didn't want to drill them, so I used some 3M VHB tape to mount them (from the inside) and cover the perimeter w/gorilla duct tape. This worked ok, but they would still suck water in. Not as bad as the factory ones, but still and unacceptable amount.

That being said, I decided I would try to design and machine some aluminum ones. I am a machinist, been one for nearly 40 years, so I figured I'd give it a shot.

One of the issues is the distance between the back of the cab and the front of the bed. My bed front has a bow in it, and there is probably no more than 1" of clearance. I was able to get both of mine out, but it took a 1 x 2 with a couple of door shims wedged in between the cab/bed to get them out. Based on that, I knew the biggest piece of my design couldn't be thicker than .750". I decided on a 2 piece design, with a vent piece mounted between the cab/bed and a backing plate which mounts from the inside of the cab which bolts to the vent. Both will have "o-ring grooves" around the perimeter. The backing plate will have a recess cut into it (about .030"), which will house two rubber "flappers".

I use a cheesy cad system at home called delta cad-pretty much cad for idiots (which suits me well!), but it's super easy to use. I have attached a screen shot of my design. Since it's in 2D, it's probably a little hard to understand. At work, I use Mastercam, which I have created the wireframe, and had one of engineers create the solid model from it, since my modeling leaves a lot to be desired.

Anyway, I have attempted to attach the screenshot, hopefully it works. I am hoping over Christmas break to machine one set of vents, but I probably won't test them out until spring, since my old ones (which I pulled, cleaned up and remounted using 3M VHB tape) are doing ok. Also, seeing that I live in Washington, it gets pretty wet here for extended periods.

I'll keep you posted...

 

One last thing, I have a tendency to over think things, or "analysis to paralysis". The drawing I posted has gone through many changes, but it should give you an idea.

I'll try to post a screenshot of the model when I get to work tomorrow that may make things a bit clearer...

 

@wag42

Thank you for your last two posts, and future promises of more posts and pictures.

As your own story proves, it is NOT a matter of IF anyone's original and unmodified 1999-2003 cab vents are leaking.

It is only a matter of WHEN they actually notice that their always leaking cab vents are the cause of water in the wire raceway under the door jamb, corroded cab corners that "strangely" seemed to rust from the inside out, fogged up condensation on the interior surface of rear glass windows, water under the front door threshold (as every time the brakes are applied, the water keeps traveling at the previous speed, since the water isn't physically attached to the cab), etc.

One reason why owners can go years without ever noticing, is because the water in the cab eventually evaporates, and more quickly so if the truck has air conditioning, which works as a dehumidifier.

Another reason why owners never notice their cab vents are leaking is because not many remove their rear seat entirely, plus remove the C Pillar trim and back panel trim... all of which are required to do in order to SEE the cab vents leaking, as opposed to just seeing water in the threshold and assuming it is the rear cab window leaking instead.

So the alternative cab vents that you are presently designing with a view in mind to machine them is a noble effort at resolving a very common problem that a lot of folks never realized their trucks had before they traded out of them.

As you refine your design, consider incorporating some of the cab vent directional drainage design cues that Ford switched to in 2004 for the inside half of your two piece vent.

 

If I had a 3D printer, I think this would be a great project for it.

 

I have been wrestling with how to incorporate some sort of drainage into the bottom of the vents. With my backing plate design, the windows serve as a stop for the flappers (so they can't move inward, only outward). They also have a .200" lip which run around the side and the bottom of each vent to hopefully keep water out. And when I state hopefully, I am far from confident they will. The .200 lip may not be tall/wide enough to serve as a stop. I am trying to keep the vet opening as large as I can. The OEM ones are 1" x 5.75" x 2=11.50 square inches. Mine are .925" x 1.4063" x 8= approx. 10.40 square inches. I may make my windows smaller and leave a larger lip. It's pretty easy to remove material, not so easy to add it back.

The material I purchased for the flappers is Santoprene. My understanding is it's actually a plastic but feels and acts like rubber. It's supposed to be more weather resistant and durable than rubber. The OEM "flapper" material measure about .023", the Santoprene I order was 1/32". I made a miniature vent assembly just to make sure the flap would work as I planned. I blew on it, and it opened, so the material wasn't too stiff.

 

Couldn't agree more!