Galvanic Corrosion - screws, sealant etc.

[hebegebe]

Would a sacrificial anode similar to outboard engines be useful? I know there are lots of choices of alloy materials for different applications. I had used one years ago in a rooftop swamp cooler that seemed to work.


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[Squatch]

I'll share a little non scientific experience. I few years ago I bought a wrecked beater of an aluminum bassboat for a project. it had seen a bit of salt water and stored with wet carpets. It also had all manner of things attached to it with various screws and bolts. The previous owner was a wood carpenter.
This pic is after I pulled the carpet. The white stuff is corrosion from salt water.


When I removed all the BS tacked on this thing The parts put together with SS screws came apart and there was no real corrosion issues around those fittings. The Zinc(Pot Metal) rod holder bases that were screwed to the hull with plated or galvanized screws had to be cut off with a Sawzall and the old screws drilled out. They had become one with the hull aluminum.

I sandblasted the hull inside out to remove the corrosion.Then started on the hull from scratch.


When I rebuilt the boat. All fasteners have either been aluminum rivets in aluminum or marine grade SS bolts and screws.


This was all completed back in 2007. The boat has been on the water since and is stored outdoors under a cover. I recently gave the boat a once over and did some overdue maintenance. I had a lot of the fasteners out and all the SS stuff came out fine and was reused yet again. I found no corrosion issues with any fasteners.

I too was confused by all the info out there when I started this. But most of the marine guys said to use good SS so I did. So far so good.

 

[Bill D]

Would a sacrificial anode similar to outboard engines be useful? I know there are lots of choices of alloy materials for different applications. I had used one years ago in a rooftop swamp cooler that seemed to work.


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This is the point of using zinc plated screws. The zinc plating is sacrificial (it isn't going to last forever though) If you want your screws to last a little longer there are products like this. Yes there are different grades of stainless steel, but there is no stainless steel that is less cathodic than aluminum.

This product resists galvanic attack by sacrificing the metal in the anti-seize instead of the metal parts under protection.



If reading the chart below, you will notice that Magnesium, Zinc and Beryllium are sacrificial to zinc, stainless is not

 

[cwdtmmrs]

Wow! This topic is interesting. I bought my camper used 7 years ago. Without any thought of corrosion, I replaced all of the non-painted screws on my camper with SS because some of them were showing rust. They still look new and none show any signs of corrosion, including the latch screws. The camper is stored under a canopy, but not garaged. I do live in dry SoCal. I agree that SS is not very strong, but neither are the mating substrates.

CWD

 

[Bill D]

Wow! This topic is interesting. I bought my camper used 7 years ago. Without any thought of corrosion, I replaced all of the non-painted screws on my camper with SS because some of them were showing rust. They still look new and none show any signs of corrosion, including the latch screws. The camper is stored under a canopy, but not garaged. I do live in dry SoCal. I agree that SS is not very strong, but neither are the mating substrates.

CWD

You won't see the corrosion on the screws. It's the aluminum that would corrode if using stainless. It turns to a white powder. Water is needed as well, so you may do well with stainless. I suggest you remove a couple in areas where you would suspect the most moisture and check out the aluminum.

 

[hebegebe]

Will a magnesium anode bonded to alum frame protect every fastener?


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[Stan@FourWheel]

Thanks for the post.

I have had the shop guys take a look at the picture, and we have never seen anything like that on the marker lights before ?

Back in 2013 the power wire came out of the frame on the left (like shown in your picture), and the ground wire on the LED light bar was grounded to the screw hole on the left, near the power wire. There was typically not enough wire coming out of the back of the LED light bar to mount the ground wire on the screw over to the right (where the big hole is on your camper) ?

If there were to be corrosion, I would think (think?) it would be equally around, on multiple screws, multiple locations, and typically on the rear wall of the camper where road salts tend to build and stay. We haven't seen any corrosion on the front nose of the FWC over the years.

And zooming in at the picture, I can't see any corrosion around that big hole, but it looks more like a puncture? We have seen corrosion with screws reacting to the aluminum over the years, but it looks much different on the aluminum skin when that happened. If the screw corroded the aluminum sides, I don't think it would eat away equally and remove all of the wood paneling backing that front aluminum skin as well ?

I would tent to rule out corrosion, and maybe it was something that happened when the original owner had the camper? Hard to say one way or another without having the camper here. But thank you for sharing, as we really like to see these things, so we can make changes & improvements when needed.

We have made several changes and improvements since then with fasteners and wiring too.

BTW: I really like the way you made the plate to cover it. Looks great !



.

 

[cwdtmmrs]

I removed a couple of the latches today where I changed to SS screws years ago. Everything still looked new. Maybe it is the climate.
No reason to change back now.

CWD

 

[resto]

I am planning to do another Ranger2 (Eagle) build for a friend. So I will be looking for another one in rough shape like mine was initially - see my build 4WheelResto

If anyone is aware of where I could purchase one please send me a PM.

In that build I plan to use SS screws and hardware extensively. I feel I have a good idea of the pitfalls of using SS and how to avoid problems having done my "experiment" (written up in that build).


Here is a picture of what I started with. The screws were kinda rusty as the camper was old and had been exposed to rough conditions. SS would have done better.

 

[cwdtmmrs]

Wow! That is ugly! I like the Ranger II model with the wings on an early Toyota. They just look more "finished" and fit better without the big gaps on the bed sides or in the rear. I paid $1,000 for mine loaded and in absolutely great shape.

CWD

 

[resto]

CWD, $1000 for a camper as nice as yours - that'll work.

I won't be holding my breath expecting someone to PM me with a camper in the great condition of yours - and at such a good price - I'm expecting I will have some work ahead.

With regards to loping off the wings on my Ranger II, I didn't mean to desecrate the camper, but was forced by my stock 4 cylinder engine, to cut weight and drag wherever possible. You have to remember my '88 Toyota truck has about half the HP of your turbo charged version (very jealous).

Desecrated wings, but SS steps and latches:



Resto

 

[cwdtmmrs]

Wow! Beautiful work resto! Not to change the topic, but did you notice a difference in drag with the wings removed?

cwd

 

[resto]

CWD, I can't tell you whether I noticed a difference in drag with the wings removed because the previous owner, at my request, had removed the sheet metal around the tailights so I wouldn't have to bother with wiring the tailights to get it home (one of the campers tailights was also damaged /not usable).



My expectation was that difference by itself would not be noticeable; but the various accumulated reductions in weight and drag would be noticeable.



I also like the look of the wings on the older Toyotas, somehow those wings make it seem more integrated, more like a mini-motorhome. I especially think the colors I used would enhance the look of the wings. But the main reason I removed the wings was I was considering getting a newer Tacoma and I don't like the look of the wings on Tacomas so much. The next build I do will be different based on what it goes on.

This explanation relates strongly to this thread in this way...

It is my belief is that the guy that has the "best camper" is the guy that uses it the most - not necessarily the guy that has the prettiest camper.

But lots of people wash their cars, some wax their cars, some will buy new tires and/or wheels to enhance the look of their cars. Their is nothing wrong with adding a little bling in addition to using your car - or camper.

Stainless steel is a great way to add bling. You just have to be careful of the products you choose and/or how you mount these fasteners.

Stainless steel is super durable. You just have to be careful of the products you choose and/or how you mount these fasteners.

Some of the problems attributed to SS are actually from other causes. When I did my experiment with various fasteners (written up in my build thread 4WheelResto ) I noticed that any significant bubbling of paint for example, was due to scratching paint under the fasteners head (like from over torqueing thus "spinning" the screw), or screw heads in slightly crooked leaving one side proud of the sheet metal (allowing a gap on that side between the screw head and the sheet metal. I did not use silicone on the screws which would have exacerbated these problems. None of the SS screws (chosen by a salesperson at a fastener company that supplies to marine customers) used in the experiment showed any sign of corrosion relating to the stainless steel.

SS latch. Beautiful and durable:







Resto

 

[craig333]

I have a pretty good collection of nuts and bolts, its really nice not having to make a parts run to complete most of my projects. Except now you guys will have me all worried about what I'm using. One more thing to lose sleep over

 

[cwdtmmrs]

If my latches ever need replacing, I will go to SS as well. they look great!

cwd

PS.The Wings on your camper had already been trimmed to fit a truck other than a Toyota. They normally would extend down the bed another foot or so and angle up.