Undercoating a 95' for the first time

Does ALL the water drain out of your bathtub after you pull the plug? No. There's always moisture and small puddles left over.

Also, the inside of a frame is cold(er) and dark, so less likely to evaporate.

There is also sand mud and dirt that gets flung inside the frame rails that holds on to a lot of water.

 

These holes are small and can easy be clogged. But even if they are open there is not enough "fresh water" to come into the boxed frame to wash out dirt from there. So the water, dirt and salty sludge enters the inside of the boxed frame through the holes on the side and from the top rear where C-section transitions to boxed and stays at the bottom of the boxed frame. Any water that enters the frame makes that sludge wet, but does not wash it out. Perfect recipe for converting steel into rust.

By the way the first thing to go is the part of the frame in front of leaf spring hanger. The reason for that is that this spot traps most of the sludge that enters the frame. If not washed and treated with FF or similar waxy stuff it will rot first.

Now regarding rubbery coating, it can easy clog or reduce the size of the drain holes making things even worse.

 

this particular section is not sealed up on top or anything? i have not found any pics on TW for this particular area yet that i must be aware of
i have not yet removed the box on mine to give it a real good inspection and cleaning yet, waiting for some warmer weather and capable hands to help... still figuring out a gameplan for next year

the easy clogging of holes is most likely due to delaminating paint coating chips on the inside of frame?

good stuff here, thanks

 

If you get a garden hose and pour water where the C-sections converts boxed part, you will see a water coming through the tiny drain hole in front of leaf spring hanger. It's hard to take pictures of that area. This is the best I have - look at that hole pointed by the arrow:



Ant look at that tiny drain hole for the whole rear section of the boxed frame.

 

This has been discussed before. The entire frame is coated inside and out (it's dipped) in a coating, however this coating was not applied thick enough, and/or the coating itself was not resilient enough to resist heavy winter climates where there is a lot of salty water (or salty air in the case of coastal areas).

I'm not really sure where you're going here. What "box" are you talking about removing?

No. as was said, the clogging is from grit and dirt ext, not from chipping paint.

There is surely delaminating going on, but the delaminating is because corrosion/rust is getting underneath the paint.

 

i learned something new today

 

NEVER use a product that dries and hardens on as undercoating. Crap and moisture will eventually get behind it though cracks or chips, accelerating the corrosion process as it gets trapped between the frame and these coatings

The best option is oil-based undercoatings, like Fluid Film, Krown and similar products. But these are good only if you apply them on a YEARLY basis. But their consistency is both their strenght and flaw. They have water-like consistency and will creep anywere, into the smallest crevice and corner BUT this consistency will also allow them to get washed off on areas exposed to elements. This is why you must apply it yearly

 

delaminiting paint is definitely what is causing my drain holes to block after a real good hosing out, although at the local salvage yards i did my schooling at this summer, those trucks definitely had some dirt all mixed in in the real bad parts
by box i mean pickup box, aka the bed, whatever it is called

 

Yeah, what I mean is that the delaminating is not what's causing the rust to occur, is the other way around. What starts the rust is clogging from dirt and grit, and just that water tends to sit inside the frame.

 

now you have me even more worried!

 

It is because of a phenomenon called condensation. When switching from hot to cold and cold to hot temperatures (the change of seasons, basically), it does create moisture in the frame. Not enough to make your frame rust as it will evaporate eventually, but when mixed and trapped with dust and debris inside the frame, it does not evaporate and it makes it rust, rusting through over time if the dust/debris clumps are not cleaned. Add the winter salt and chemicals to the mix and it accelerates the process tenfold

But down south, there isn't season changes as brutal as up here, that is why the inside of frames may be dusty or have debris in there, but the inside of the frame is in good condition. Very little to no moisture gets trapped in there due to the absence of the condensation phenomenon

Or course, if you drive or park in a pond, that's a different thing...

 

But why is the paint inside the frame chipping off, that's not related to condensation. Bad paint or improper preparation of the surface to be painted

I'm working on bed rails for my truck and I'm using used steel bars that are at least 30 years old but the paint is still hard as a rock and does not want to be removed, even with a drill wire brush

 

It's all related, it's kind of a feedback loop.

You've got the inferior coating (either in chemistry of the coating or the thickness), so condensation and the dirt and grit (mixed with road salts) that holds on to even more moisture just sits there. That junk eats into the inferior coating more easily than it would otherwise, which then leads to more holes, which leads to more corrosion, which leads to more holes.

 

i like the science of all of this
its much better than the shrugging of shoulders and bewildered look the Toyota dealer service dept assistant gave me when i asked him about all of this on a recent visit

 

I use Great Lakes Chemical on my vehicles.

 

It's honestly really simple. People over complicate it all the time.

If you don't want rust, keep the metal clean and dry.

Don't use treatments that are "permanent" because they just mask problems.

At least once a season, preferably twice (at the start and end of winter) but at least at the end (so you don't have all that grime sitting there all summer), get a hose/pressure attachment and get INSIDE the frame and clean it out. Then treat with fluid film using any one of the many methods people have developed over the years.

I'm no expert since I don't need to be, but search around, you'll find plenty of people who treat the inside of their frames.

 

i will say another possibility is the use of a heated garage to park your truck in during the winter. It will also greatly accelerate the rot and cook it during the night
... it would be good to know how many bad taco frames were once tucked into the heated garage in the winter evenings

 

yes woolwax is a tad thicker. as for staying power I'm not sure. I have used both and don't see that big of a difference. No smell. one of the biggest complaint from my customers.

 

would woolwax pass the undercarriage auto power wash test?

 

OP, if you google fluid film, on their website is a locator for places that apply it for a fee. Part of the process is power washing the frame indie & out then drying before application. I was going to have it done last year when we went to Vermont to see the leaves change color. Didn't because it would have taken two whole days out our short time there. Seems like the price quoted was under $200.