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ok, so i'd like to know what you guys recommend for rust removal, i'm cleaning out the battery well, and while i can get a lot of the rust out with sand paper/scotch brite, but under where the battery sits is really bad, and i have no way of getting to it. i've heard of "Naval Jelly", how does that work? Thanks a lot, after its all clean, i plan to just spray it with some rustoleum, any thing i should do in addition to this?

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My suggestion would be to take the battery tray out. You can get a spot weld cutter from Eastwoods for a reasonable price or get one locally. Drill out the spot welds until the tray comes loose, some may be impossible to get to, these you may end up using using a regular drill to remove. When you are done you could re-weld or bolt the tray back in. This is the only way to get at the rust that you really need to get to. If you don't get it taken care of the next thing you know you will have a large hole there, and then it can be hard to replace.

Clean out the rust any way you can, wire brush, sandblasting, putty knife, sandpaper etc. If it is bad under there when you get done you may find you do have a hole that needs a patch panel. This is in a important place so take your time and do the best you can, as it is a seam that attaches the inner fender to the firewall.

When you are done I would say to use a self etching primer on the bare metal (Eastwoods has an aerosol) and use a good paint to finish. Or you could use Por-15 or the Corroless from Eastwoods if you prefer, they will seal the area to prevent any further rust. The main thing is get the tray out of the way and get it as clean as possible under there, any rust you leave will continue to eat away the metal, if you can't reach it, you can't take care of it.

One idea I have is after painting the engine compartment in my car, I think I may get a aerosol or roll-on pickup bed liner material and cover the area under the battery tray down to the top of the frame rail. This way any future spills (if there are any) hopefully will not get to any metal. Maybe it will work, maybe not, but it can't hurt to try. Use a good battery tray or mat under the battery when you are finished to prevent any more small spills.

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Yes, it may seem like a lot of work, but having the rust go on eating away at your car will cause even more work sooner or later. Much better to do a little work now than to do a lot of work later, or in the worst case, end up sending the car to a junkyard when it could have been prevented. I had a 72 not long ago that didn't look too bad on first look, but when I took off the fender and started poking around large pieces disappeared. When it was done all the inner fender under the battery tray was gone the width of the tray from the frame rail all the way up the under the tray, plus a piece was gone in the firewall. After one afternoon of poking around the car was beyond hope, and I ended up parting it out and sent the chassis to the crusher.

The battery tray I believe is actually made of a slightly thicker gauge steel than the fender so it may not be past hope yet. You'll have to decide when you clean it up.

BTW, you should check the frame rail area carefully above the t/c rod mount too. If acid has run down the inner fender it is possible it has run down into the frame rail as the weld seam is not sealed, and the frame rail is starting to rust out from the inside out. When you are finished with your repair I suggest using a seam sealer to seal the top weld flange on the frame rail all the way to the radiator support to prvent any more water etc. from getting down into the frame rail itself. Anywhere there are gaps in a seam is a point where water can get in and if the drain holes are plugged it will never come out, at least till it rusts out.

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I agree with my fellow Z nut on this one. If you have rust underneath your battery tray, drill through the spot welds and remove the tray.

There is no way you can be guaranteed that the rust inhibitor got down inside those cracks and nooks....

I purchased the Eastwood spot weld drill bit. It works great. But, I drilled holes completely through. I did this so I can merely bolt the tray back into position. If I ever become suspicious of rust or whatever leaked down in that area, I just need to remove a few bolts to get the tray out again. :)


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MrMoonshine: One of the nastiest things about rust is that, like an iceberg, you only see the top of it, and the bottom can be HUGE! Additionally, only taking care of what you see, is like stepping on the one or two termites that fell out of the light switch hole when you change the face plate in your home.

Too many times have I seen "surface" rust be rust-through. Or seen "mild" rust turn out to be serious panel weakening ready to provide Flintstone brakes in a vehicle rust. The sad fact about the 240 Z is that the engineers used very thin sheet metal in order to keep prices down, as well as doing the Japanese market "no one keeps cars longer than a few years" mindset in mind.

(Did you know that there are a couple outfits that import engines and other components from "junked" Japanese mainland cars to the US, simply because in Japan they don't restore / maintain older vehicles?)

Additionally, since this was their first serious directed attempt at penetrating the US market, they were not aware of many of our "quirks" and idiosyncrazies. (In Japan they do in fact, own their cars only for a few years.)

So, bottom line, do the "hard" work now, it will prevent it from being IMPOSSIBLE later.

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