460 swap into a 78 Bronco

Just realized... I will probably address the cowl seal / drain leak (apply a rubber based sealer) before I do anything else !! I am pretty sure that all of that is backed up. Last thing I want is for water to get under the carpet, under the water proof layer and stay there and rot things up!!

I probably should not get a water proof mass backing layer for this reason, so I can tell if there is water in the cabin by checking the carpet for dampness.

viven44 wrote

I have thought about media blasting. I probably will end up doing that, is there a good portable setup available ?

You think your neighbor dislikes you now????  

I don't like it because it only sticks to a crappy substrate, and as Gary says, nothing sticks TO it..

If you're painting a rusty frame with a brush and roller in your driveway, then it has its place.
ALL the rest is marketing hype and a legion of users that don't know that much better products exist.

(The opinions presented here are not necessarily those of this station or the broadcasting company)

Gary says as long as its tacky when the top coat is applied, it would do well. Right ??

Oh about my neighbor.. City came in and said I was allowed to work on my own vehicles. The inspector even asked me if Big Blue was for sale. Another neighbor's kid randomly stopped by yesterday and asked me if I wanted to sell  The inspector said I should call in my neighbor for trespassing

Glad you got that situation resolved.
Media blasting is still sure to cause more friction.  

Sure. You can crawl around on a tacky floor and paint it best you can.
Like I said, I'm not trying to stop you or sell anything.
Just that there are much better products, and they have no time constraints.
If you have no problem with the window of opportunity (or retirement means every day is a Saturday -except Sunday- like Gary) then go for it!

I'll keep that in mind!!

If I was able to remove all the rust well with media blast, I would even do Fiber glass skim coat + the usual body work finish approach

You can remove all the rust with acid.
It will eat all the iron oxide before it touches solid metal.
Chemistry is fun! (and useful, sometimes)

I often use acid to clean a part. it works amazingly. but then I have to smell it. neutralize and clean. it too is a process which take time and care. but when done right you have all of the available steel left to work with. too often we abrade the part and remove much of the good steel and still have rust pores. unless the rust is neutralized it can contain enough oxygen to continue to grow under a perfect seal.

I loaned my portable media blaster to my brother on a "permanent" basis.  I hope to never need it again.  The amount of media I found in my body cavities as well as the huge amount of media it took to do anything made the thing far less than fun and very expensive to use.

They require a lot of air and you need very dry air or the media clogs.  So you need a very large compressor as well as a drier to get rid of the moisture.

I have a 50 gallon compressor with an in-line drier ... sounds like the cost of media might be prohibitive for any large job.

Yes agreed.. neutralizing has to be done to let the metal stop etching. The problem with neutralizing is that it is a basic solution (PH>>7) and oftentimes an oxidizer in-of-itself, and therefore needs a really good water rinse to rid of all the excess chemistry. Before it is removed it will do the job of forming a non-zero oxide layer (which is needed). Most paints/polymers rely on an oxide bond as native/bare metal doesn't have any good chains to bond to. The issue however is that the POR/paint, if and when it delaminates, you have almost fresh metal underneath that is a nice food source for trapped air/moisture that gets under the delaminations. Sounds like POR-15 is pretty robust in that department, but I assume it needs a good process of application to ensure no polymer cracking, etc.

POR metal prep's MSDS shows to have phosphoric acid and alcoholic base both working in unison to etch and oxidize.

I am leaning more and more towards physical removal, and I have always preferred that. I like that because it will remove any rust that is not adhered well and then whatever rust that is indeed still present is bonded well to the base metal really well and also a decent passivator. As mentioned, many of the paint over rust chemistries / polymers / primers do rely on a slightly oxidized metallurgy to form a good bond so some native rust/oxidation is preferred.

My neighbor needs to deal with either chemical residues in the alleyway or maybe the sound of air compressor running!!

"Rust Never Sleeps"....

It's mostly sulfuric or hydrochloric that are awful.
Phosphoric acid, like Kleen-Strip Concrete and Metal Prep pretty much only needs rinsed off when it's done.
Oxcylic or Citric acid don't smell too bad.
Citric is REALLY cheap, in bulk

Yes chemistry is fun! 25% of my job is to come up with ways to prevent copper corrosion in metal traces used in electronics. With a fab, there are even other methods at disposal to clean metals such as plasma etch, reactive iron etch using oxygen, fluorine, etc aside from wet etch chemistries.

Or..... just use an acid etch primer, like is sold just about everywhere. 💡

It certainly doesn't need any extra steps .

I have always wondered about those. Let me see what I find after media blast ! Maybe media blast will thin-out the metal some more and now I need to beef it up by building it up with a fiberglass filler.

I wish I had media blast while I was doing the cast iron intake manifold. It would have cleaned it up awesome!!

Any ideas of what would cause that rust pattern? Trying to guess what kind of water leaks that may have to be addressed in the cab.. or if this is just from water from shoes that soaked the carpet

I would check the seal around the windshield.  The mastic that was used dries and cracks and then leaks.  So I'd put a hose on it and see if you have a leak.

Water goes down…

So in your pict, left part of the rust surely comes from the front retaining bolt for the seat railing.
Silicon-seal it when you’ll put back your seat.

For the right part, this could be water from windshield as Gary said, or from some free hole in the firewall.

If it was from boots, well, the left side should be rusted same as right, unless the previous owner was a one-legged person.

Lol. who knows maybe both sides were one-legged occupants and why they wanted an automatic transmission.

Can you please expand a bit on "left part of the rust surely comes from the front retaining bolt for the seat railing.." not sure I follow.

Yes good idea. I'll run a hose before installing new carpet.

I suspect that this bolt lets water flow into the cab.