Unscrew the phillips heads bolt at the top rear of each rear wheel arch. It has already been removed in this image and goes into the white plastic clip.
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Detach the strap which supports the lower edge of the outer fender on each side. The bolt at the fender is prone to break, so take out the one at the frame if the other seems stuck.
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Locate the two towing hoop brackets under the back end. There are three 10mm bolts holding each bracket. Remove these. They are likely rusted solid. Use an Impact Wrench!! You do not want to break the bolts or the welded nuts inside the inner fender component!!
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One of the welded nuts sheared and I had to grind it off. PITA.
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The fender is now completely loose except for one annoying push/pop clip on each side of the outer fender. You have to reef straight out on each side of the van about a foot behind the wheel arch. Again, PITA. Below is what the clips look like when you've got them unpopped. Now the whole fender just slides out backwards.
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If it's anything like mine you've got a real rusty mess on your hands.
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The outer fender is attached to the inner with a bunch of bolts along the top and bottom edges. Every one of these was rusted solid and either broke or pulled the plastic tabs off and started spinning. I had to grind the heads off all the bolts that did this. This will almost certainly result in melting the tabs which the bolts are mounted to, but since the tabs are broken it doesn't really matter.
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At least now you have everything apart.
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After I had it apart I began hammering on the inner fender and holes started appearing all over as rust fell off it!
I am posting this so that it might encourage others to get in there and do a bit of maintenance and re-painting before it gets as bad as mine.
When I figure out what I'm doing with my lump of iron oxide I'll do another post.