Ok, while rebuilding the rotted out passenger longitudinal on my car I came up with an idea. How about a port that can be used for access to the interior of the longitudinal for inspection and other purposes. For example while my passenger side is going to be fine after I reconstruct it, I "think" the driver side is golden, however, I don't know for sure. Even if it is good, I would like to treat the interior of the driver side with some type of rust proofing (Metal Ready and then POR 15 most likely). But how do I get into that section without cutting a hole and then welding it back?

Here is my idea. In the front fender well there is a small area that if it had a port cut in, would allow you to view and/or access the entire length of the longitudinal. Items like the heater tubes and brackets will be somewhat in your way, but otherwise it is a straight shot down the length from here. I was thinking that a hole (maybe 1" in diameter or so) could be cut in the wall. Some type of "bung" (large diameter flat nut) could be welded in place and then a plug could be screwed into the bung. You could seal the threads with your sealent of choice, etc. to keep anything from getting in. An example of using this would be that a wand used to spray Metal Ready or thinned POR 15 should be easily snaked down the length via this. Every few years you could open it up and check to make sure things are OK. I don't like cutting up the car to do custom stuff, but I think this is maybe something I can live with.

In the photo below is where I am thinking about doing this.

Click to view attachment

I have looked at McMaster-Carr and I can't find a flat nut or some other type of weldable nut or bung that is of large enough diameter (1" or so). I think the plug is going to be easier to source than the bung. I would prefer metric threads, but I am thinking if I have any hope it might end up NPT or some other non-metric thread. Any ideas for source of a large diameter bung or how to create my own (i.e. thread 1/4" metal plate to make my own)? Is this a good idea or not? Opinions welcome!

I should have mentioned that I have thought about a simple plastic plug as well. I think that would work, but you would have to use some type of sealent to keep it from leaking and with that being directly behind the front wheel, I am afraid the plastic is going to get beat up and torn apart while the metal bung and plug is going to outlive the rest of the car.

or, just use the rather large oval holes that are already there ...

on the inside of the long, covered by a oval piece of tar ...
Andy

I have the tar patches off the oval holes in my car. IMHO, The rear one is nearly completely blocked by the flex heater tube. The front is mostly blocked by the metal heater tube pipe. You could snake something (such as a wand to spray) through one or both, but you can't really use them to visually inspect.

Interesting idea, but I wouldn't put a hole in the wheel house, too much of a chance for water to get in.

If they are treated and sealed from corrosion, they wouldn't need inspection.

I love the idea of an access hole.
I totally agree with Perry...that is the LAST place I could put it.
Seems they all get rust in the wheel well eventually...
Look for a less likely place for water to penetrate IMHO.

For the plug, look into boating parts catalogs....west marine has alot of interesting plugs for drains etc.

Rich

Use a rubber freeze plug from an American engine. They come in a variety of sizes up to 2" or more and make an ultra-tight seal.

I was thinking along the same route. I was planning on welding in a patch when done. But isn't there a bracket in the way that prevents getting towards the back? I was thinking there is a bracket for the sound absorber in the front. I haven't torn one down to see. As far as the patch goes, a good epoxy would work to hold a oversize patch in place. A little heat and it could be removed for later inspection.

There are two brackets that go top to bottom that hold the heater tube metal pipes. But they don't cover the entire width. It's tight, but you should still be able to see the entire length in some places.

If I can't find a good source for a large bung and plug (cue Beavis and Butt-head laughter) I may just cut a hole, do my treatment, weld it back up and cross my fingers.

The heater tube blocks a good bit of the access through the long. There is already an access hole in the front portion of the long- accessable from the inside of the door jam, behind the speaker location. Can't see in there unless you have a boroscope, a viewier on a flexible wand. However, you can relatively easily access the front portion of the long with a flexible hose to flush it out, dry, and then apply a sealer inside. Also, as mentioned earlier, the oval ccess ports on the insides of the longs can be removed. I used a flexible hose from Eastwood that has a right angle sprayer attachment on the hose. This can be used to spray inside the long, passing it through first the front hole I just mentioned to get the front half of the long. Then you can use it to pass through the side hole to treat the rear half of the long. I sprayed POR 15 metal treatment stuff, and then rinsed very, very well. Let it dry for several days, then heated it with a hot air gun to remove all remaining moisture. Then sprayed the inside with POR 15. Should be pretty good for a while. Make sure that drain holes are still open after all this.