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Hog Troughs, Again


boogieman
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Thought I'd stir the pot a little. Has anyone ever cut into a body to see exactly where and how water gets in there? From the cowl area but by what means? A passage-way, a drain hose, a gaping hole? What about the drain hoses from the sun/moon roof units? I have read of drain hoses in the windshield (A Pillar) posts, hoses to the rear in the B pillar, and even to the trunk area. Any of the above? All of the above? No standards?

The troughs on mine look good in pictures. Haven't been able to inspect them as the car hasn't arrived yet.

Depending on how the water gets into them, I'm thinking of a means to seal them completely. Might not work but based on info I'm willing to try something radically different.

A good friend owns a structural spray foam insulating business. If the cowl, sun/moon roof, and quarter-glass areas drain there through hoses, why cant the hoses be extended/replaced to drain somewhere else or through the troughs to under the car? Then by access holes, easily covered with floor pan plugs, fill the troughs with structural spray foam. The expanding foam will fill every crevice, nook, and cranny of the area, and provide a stiffening quality to the area hanging over the frame between the wheelwells and completely seal that area from future water damage. Not to mention the sound and heat transfer properties inherent in the material.

Being retired from the construction/remodeling industry I see this as a viable solution. I have used this type of sealing/water-proofing/ insulating material in the most unlikely of situations to great positive results.

This could even produce positive results on cars with partially rusted-out troughs. Make simple aluminum/steel panels to cover the damaged areas. Pop-rivet them on. Fill with the foam. Sealed and structural support partially restored. Except in the roll bar location.

Nothing is perfect but this is possibly a low-cost, temporary, viable, alternative, solution to $5,000 worth of expense and down-time.

Let the debate begin.

Boogieman

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I'm no structural or automotive engineer so I can't speak to your idea on the foam or patching hog troughs but it has always seemed to me to do the job properly or don't do it at all...halfway measures seem to be weaker than correct repairs...or just like being just a little bit pregnant...the baby (rust) will keep growing. Another potential problem is...if the hogs are rusted to the point replacement is required...there's often frame issues to be dealt with as well. A quick-fix or band-aid on the hogs doesn't fix frame rust.

One source of water in the hog troughs is that the drains from the sunroof lead right to them...with no way to drain the troughs. Not exactly the best design.

What I've seen suggested as an idea that sounds very good, is to drill a couple of 1" holes in the hog troughs...enough to insert a spray head and mist it with some kind of protectant. You can then snap in removable plastic body caps to occasionally drain out any water that accumulates. How well this works I can't say but it sounds like a far easier and equally effective method to accomplish the same goal. If it's not practical or possible to seal the hog troughs making a way to keep them drained and dry is preferable.

I'm not trying to rain on your parade...maybe you have suggested a good way to reinforce degraded hog troughs...as I said..I'm not a good judge of that. Maybe someone else can add to the conversation.

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The foam idea has some merit if it's closed cell foam which will keep the moisture from permeating into the trough. The problem is that the hog troughs have many places that the foam needs to seal. The entire surface between where the fiberglass and the metal needs to be sealed. The troughs themselves have small open areas where they are bent and the pieces are spot welded together as well as the holes used for the rivets and drains from the roof. If the foam could form a perfect seal between the metal that would guarantee no permeation of moisture then you might have a chance. The problem comes if any moisture does get in you have established a perfect environment for rust to start it's disastrous pass.

I just don't have the faith in a product not engineered to do the job succeeding. The other problem is that once filled with foam it's impossible to very difficult to reverse in case of issues.

What I did on my 83 after I repaired the soft areas in the hog troughs was to drill several 3" holes through the floor into the hog troughs for access and some smaller holes for the troughs to drain out the bottom. Then with a couple of brush variants I slathered POR-15 over every inch of the surfaces inside the hog troughs and let them drain until everything was setup. I then plugged the holes in the floor and added insulation and carpet.

This gives them a chance to dry out if they do get some moisture inside. As I said, I'm just not confident enough in keeping the moisture out by filling them up.

Bob

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Points well made. As with anything out of the ordinary, nothing is guaranteed. Given enough access the foam will force itself into and out of every opening as it expands. And I'm not suggesting the type of foam available in the spray cans from the home supply box stores. The commercial grade material is a dense closed cell formulation, unlike the other readily available stuff.

No offense intended Bob, but can you be sure every square inch of the troughs in your '83 are covered and penetrated with the Por -15? It may be the case, I certainly don't know. If you are happy with your effort then it's settled.

I am simply offereing a new and different potential perspective on the bain of inherent desigh flaws on our Avantis. The foam being considered is truly water, wind, and thermal isolating. I just need to determine where the water is getting in by what means before I procede with my idea.

I know from reality that this is probably a temporary fix. After all, not everyone has the financial means to put another $5 grand into a car worth, in most case, barely triple that amount. Others need to wait and save for such an expense.

Just throwing out grist for the mill. Every situation is different and alternatives just might add a little more life span and usefulness to the cars in question. Anything that extends the life-cycle ought to be considered.

And some of our cars are about 50 years old, too. And many have been neglected to the point of shame for the previous owners.

I do appreciate a lively debate.

Thanks for your input.

Boogieman

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No offense taken, I'm very hard to offend anyway. I know the bottom and sides are because they are visible through the holes. The top attachment is the least of the worries as it's the last place to rust out.

I know the foam you are addressing quite well and, as indicated in my original reply, would be my choice if I had faith in the ability to seal everything from moisture. I spent way to many years in the permeation business to be comfortable with the ability to seal this area this well.

I'm not gospel on anything and would like to see you move ahead with the modification. If it works well then it would be a help to the entire owners group. The downside is I'll be somewhere else when the long term data is available. I just wouldn't do it on mine.

Bob

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Good deal Bob. I haven't pulled the triger just yet. My concern is where and how the water gets in there. I would hate to fill and seal that area with no means of diverting the water away before it got there.

As an example, if the cowl/plenum area drains through a trough so to speak, where does that water have to go? Through the floor vents to the interior? Or to accumulate until the cowl area is full? And the moon roof drains to where? And the quarter windows, assuming the exterior seals aren't 100% effective?

Lots of questions I have no answer to as of yet. I may never do this but willing to investigate the possibilities. Not about to seal them off without some due dilligence.

Mine are supposedly in good condition but will find out for sure when the car arrives here.

Boogieman

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I think it might be better to let the water flow through rather than dam it up. The water will just accumulate somewhere else and cause a new problem. I would drill holes in the trough to let the water escape. Most doors and quarter panel trunk floor extensions have this from the factory. As long as the water has a means to drain it works well. They fail when leaves and debris clog the holes.

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Got the car yesterday. Troughs could not be more solid. I want to learn how the water enters the trough area, not just from where. This will help me decide wheather or not to procede.

On my '79 there is a 1/4" hole in the bottom of each trough, but about 1" from the rear. The car has a nose-down slight rake so I don't see how that helps. I might put a small hole in the front area too. Either way, they are going to be wire-brushed, POR-15 coated and undercoated too. Possibly with a bed liner brush-on material. Haven't decided yet. Just now able to get started on the preservation.

I'll let the forum know.

Boogieman

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