So, is the tailgate of the Gladiator NOT metal?

[seven30]

It doesn't rust, but it does corrode!

Believe me, 20+ years in the aircraft industry, Aluminum does corrode big time! It doesn't get big red rust patches, it gets white patches that eat it away like a cancer. Basically just like rust.

Look for it to start anywhere that the aluminum touches another metal. Screw holes, frame interactions, etc...

Exactly. Corrodes around screws and ferrous metal contact points. I have a 1964 GMC coach. Almost entirely aluminum. The only signs of corrosion are where steel parts are in contact with aluminum. Back in that period they used a lot of zinc chromate coating that helped slow down corrosion but it would need constant attention if driven in the east coast winters.

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[Bulldog10]

Seems like it's not -- I tried to put a magnet on it, and it wouldn't attach -- it DID attach to the fender, but NOT the tailgate?

Aluminum-same as doors!

 

[seven30]

What about the sport hood? Is that steel or aluminum?

 

[ShadowsPapa]

It doesn't rust, but it does corrode!

Believe me, 20+ years in the aircraft industry, Aluminum does corrode big time! It doesn't get big red rust patches, it gets white patches that eat it away like a cancer. Basically just like rust.

Look for it to start anywhere that the aluminum touches another metal. Screw holes, frame interactions, etc...

Yup. I work with aluminum on a much smaller scale than aircraft, and I've run into some things that literally crumble. I should take pictures of the ALUMINUM scuff or sill plates used in my cars - the edges eaten totally away, screw holes eaten away
(like you said - steel screws through aluminum into the steel rocker and sill panels below - ELECTROLYSIS)
It's why Jeep has isolating pads between the hinges and hood and other key areas.

At first it's sort of a white, fluffy stuff. I have pieces I've tried to clean and they end up looking like the surface of the moon once the white is removed.

Aluminum is also on the list of active metals (compared to noble or non-active metals) (active metals lose electrons more easily......)

I found a snippet here to explain it a bit for the LURKERS who wonder -
Although it does not seem to be particularly reactive, aluminum is considered an active metal. Its behavior is deceptive because it reacts rapidly with the oxygen in the air to form aluminum oxide (Al2O3), or alumina, which is tightly bound to the metal and exists as a dense coating (unlike the oxides of iron)

 

[ShadowsPapa]

Exactly. Corrodes around screws and ferrous metal contact points. I have a 1964 GMC coach. Almost entirely aluminum. The only signs of corrosion are where steel parts are in contact with aluminum. Back in that period they used a lot of zinc chromate coating that helped slow down corrosion but it would need constant attention if driven in the east coast winters.

Electrolysis happens - if there's moisture present.
Zinc is a sacrificial coating and self healing in that even if a zinc plating is scratched, the metal below is still protected until the zinc is gone far enough. (I do zinc plating and passivation)

 

[rharr]

My hope is the Jeep engineers paid attention in class when galvanic reactions were discussed.

 

[Rocksalt]

the tailgate is plutonium

 

[seven30]

the tailgate is plutonium

Doesnt that cause corrosion of adjacent vehicles.

 

[ShadowsPapa]

the tailgate is plutonium

FBI is looking for your tailgate..........

 

[ShadowsPapa]

My hope is the Jeep engineers paid attention in class when galvanic reactions were discussed.

Check the hood bolts - I see some shields around the screws and what looks like an insulator between hinge and hood. Plus if the paint seal doesn't break, you are fine.

 

[seven30]

Check the hood bolts - I see some shields around the screws and what looks like an insulator between hinge and hood. Plus if the paint seal doesn't break, you are fine.

The hood on the Mojave is steel. And heavy. Not sure about the Sport yet.

 

[steelponycowboy]

I figured that out a long time ago. Tried to attach this magnetic sticker to the tailgate.
Had to put it on the side. Fail to understand why Jeep did that. Save a few pennies I guess.

Aluminum is more expensive than steel. They did it to save weight and to help MPG. The bad news is if you get it damaged, has to be replaced.

 

[steelponycowboy]

The hood on the Mojave is steel. And heavy. Not sure about the Sport yet.

Sport is steel. European Rubicons are steel, US models are aluminum. Go figure

 

[ShadowsPapa]

Sport is steel. European Rubicons are steel, US models are aluminum. Go figure

Why would the Sport hood be steel? Overland isn't - should be the same hood.

We also have different CAFE requirements as well as different collision requirements - could be part of the explanation.
Who knows what the EU rules are...........

 

[ErylFlynn]

Exactly. Corrodes around screws and ferrous metal contact points. I have a 1964 GMC coach. Almost entirely aluminum. The only signs of corrosion are where steel parts are in contact with aluminum. Back in that period they used a lot of zinc chromate coating that helped slow down corrosion but it would need constant attention if driven in the east coast winters.

It is called galvanic corrosion and happens to many metals when in contact with a different metal. Rates, and details of course vary by metals. Why you need to be careful mixing metals and some times what bolts you use later after the fact. You could replace a bolt with what you think is better, and create corrosion and damage the area.

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