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Discussion Starter #1
I bought my car in 2010 and it seems like there has been white powdery stuff around the seat mounts forever. I would vacuum it up and think, Man I have to do the wet seatbelt repair some day. Well, the car has set for over 2 years now and I just rebuilt the trans and planned to start driving it again. I should have taken a picture with the seat in it, but if you see any white corrosion around your seats you better not put off a repair.

Fortunately, because of another member's misfortune I have a corrosion-free seat mount I'll weld in. I think I also have to do the rear mount which will require cutting out a section of floor. It's a smaller repair, but I think more difficult.

I live in Washington State and was pleased to go to Florida to buy this car, but then discovered it had recently moved to Florida from 5 years in Michigan. Originally it was from Washington State. It's come full circle, but I think it left some aluminum behind.

Hmm. I have to remove the carpet to brush off all this corrosion.
20200419_144613.jpg


Good grief, what am I seeing here? I actually have to dig this out!

85747


Oh no! What the heck! I was so happy to have a car that didn't rust.

85748
 

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Wow! I thought mine was bad. My driver's side front outer mount is missing some metal, but still seems strong enough. Luckily the rear mounts are fine.
 

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Wow that looks like a bad case of electrolytic corrosion!

I suggest when fixed lather it and the bolts with anti electrolytic corrosion compound and make sure surfaces are properly painted before joining the steel seat runners to the aluminium mountings.
 

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Thanks Peter. Yeah, I've been wondering how to protect things when putting it back together. On an old thread someone mentioned that the bolts had some kind of coating on them. I don't know what that would be, except that the rear bolts seemed to have red locktite on the threads. I'm thinking about making plastic spacers/washers. I know if I ever see corrosion again I won't wait 10 years to deal with it.
 

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^ Most bolts on the Insight that join steel to aluminum are 'Dacro' coated. I think Dacro is a tradename and I've never been able to find out what it really is. Probably some kind of zinc-based plating. On the Insight they're the silvery bolts I think usually with a green marking on them...

So, all that is simply from galvanic action between the steel "seat runners" and the aluminum mounting points/cross members?? (and the salty Michigan road spray)...
 

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Discussion Starter #7
^ Most bolts on the Insight that join steel to aluminum are 'Dacro' coated. I think Dacro is a tradename and I've never been able to find out what it really is. Probably some kind of zinc-based plating. On the Insight they're the silvery bolts I think usually with a green marking on them...

So, all that is simply from galvanic action between the steel "seat runners" and the aluminum mounting points/cross members?? (and the salty Michigan road spray)...
Dacro. Thanks. I remember seeing that somewhere. These bolts are black on all my cars and just look like grade 8 bolts. I'm going to use the seat frames from the parts car as they are not rusty. The car I'm currently driving has rusty mounts, but no white crusties. Remember too that this is not corrosion from below, like road salt, but must have been from salt brought in on the shoes?
 

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Discussion Starter #9
I understand that when you add a steel fitting to copper plumbing in a house the corrosion can occur anywhere in the house, not just at the connection of the dissimilar metals. It makes me wonder about the corrosion that is all over my car at all the steel bolts. I've read up on Tef-Gel that rmay635703 told us about. It certainly looks like the right stuff: ULTRA Tef-Gel PTFE anti-seize, anti-corrosion, waterproof lubricant

Take a look at these pictures. The bolts on the HV loom cover has been covered by the underbody panel so while everything is pretty clean there, ALL the bolts attaching it are like this one. Where does that corrosion start? I think the parts car is clean so when I get the Tef-Gel I'll take all of these apart and replace the bolts from the other car.

85775


And then eq1 reminded us that the steel to aluminum attaching bolts were called Dacro coated. Check out this photo of the gas tank strap bolt next to a brake line bracket bolt. I'm assuming the brake bolt is the Dacro coated one. I wonder why all the bolts are not Dacro? There are several of each under the car.

85776



I also thought you might also like to see what the seat mount cross section looks like. It will probably be a month or more before I can take this to a friend's house to weld it in (the red is paint from the sawzall blade. No Insight owners were harmed in the making of this photo):

85777
 

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Very useful pics, and questions...

I understand that when you add a steel fitting to copper plumbing in a house the corrosion can occur anywhere in the house, not just at the connection of the dissimilar metals.
Never heard that one. Not saying it can't be true, though I don't understand how it could be...

The bolts on the HV loom cover has been covered by the underbody panel so while everything is pretty clean there, ALL the bolts attaching it are like this one. Where does that corrosion start?
If I had to guess, based on what little I know about this stuff, if the bolts are steel and what it's screwing into is aluminum, or perhaps if only the surrounding material is aluminum, like if there's a capture nut, then you'll get galvanic corrosion when the area gets wet (the water is the electrolyte). Condensation on the cool, steel bolt is probably the wetness. The current that develops would travel all over the bolt, I imagine, so that's how you get corrosion on the underside. On the other hand, I thought aluminum had the more negative potential, and that the metal with more negative potential gets attacked - so I wouldn't have thought the steel would corrode... Maybe it's just some sort of oxidation from the aluminum that gets 'dispersed' over the steel??

Check out this photo of the gas tank strap bolt next to a brake line bracket bolt. I'm assuming the brake bolt is the Dacro coated one. I wonder why all the bolts are not Dacro? There are several of each under the car.
Not sure that the brakeline bolt is a 'Dacro'. Hard to tell. Is the bracket steel?
 

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Discussion Starter #11
Is the bracket steel?
Uh oh. I guess I forgot to check. Not sure when I'll be back under there. Actually, I'm sure it is aluminum or it would be rusty.
 

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^ I'm not positive it matters, actually. I'm thinking even aluminum to aluminum pieces on the car can be attached with the 'Dacro' bolts... It's not only the steel to aluminum like I said earlier...
 

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well dang that is kind of a big issue. I hate working with rust/corrosion and one of the reasons I love the insight is because I thought they were rust/corrosion proof (yeah sure fuel and brake lines are a problem eventually but easily replaceable)

are there any other parts of the insight that could corrode away with time?
 

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Don't buy a vehicle that has been driven in the area where they "Salt" the roads is a good solution.
 
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