Rust underneath battery tray

[Ben's Z]

You folks done anything in the past to get te rust off the metal underneath the battery tray? I was going to use this stuff called evap o rust and perhaps then zinc prime the metal before top coating with epoxy primer then paint. Anyone ever put por 15 on there and then painted over that?

[Hardway]

Anything to neutralize the rust and prevent it is a good thing. Priming and painting over it once the Evap rust has done its job is a good option. Por-15 is good too but I do not think its designed to be painted over. Maybe you can evap o rust, then por-15, then prime, then paint? I am sure some other members will chime in on this.

[jfa.series1]

Get rid of all the surface rust you can possibly reach. Use small wire brushes, small chisels, pointed objects - anything you can come up with to get it out. Be aggressive and thorough. If your evap o rust is a phosphric acid product, follow directions and ensure it has time to work. A plastic spray bottle usually works well for application. Rinse thoroughly and let it dry for a day or two to get all the moisture out. A hair dryer can help with all the cracks and crevices that WILL retain moisture. POR-15 does not require a primer over acid-washed metal but follow all directions carefully. Don't get it anywhere you do not want painted, including yourself. To paint over it, use a self-etching primer, then your color coat. Been there, done that. Patience pays off. Good luck.

[Mike]

If the rust is bad, you'll want to drill out the spot welds on the tray and take it completely out. This way you can sand and prepare the surface correctly. When you are ready you can weld the tray back in, making sure all of the rust is gone.

[Kurbycar32]

Mine was pretty nasty but generally intact. I brushed and grinded as much out as i could then coated the entire thing with rust bullet (same idea as por15). Eventually ill have the motor out for something, when that happens i plan on replacing the battery tray completely.

[Ben's Z]

If the rust is bad, you'll want to drill out the spot welds on the tray and take it completely out. This way you can sand and prepare the surface correctly. When you are ready you can weld the tray back in, making sure all of the rust is gone.

Nowhere near that bad thank god. If you are following my engine rebuild thread, I have my motor and trans out along with just about every other piece bolted to the inner fenders and fire wall. I have a serious undertaking on my hands now. I'll post some pictures in my engine build thread in a few days. I am going to degrease everything with purple power, then wax and grease remover and scuff sand any good areas with 320 grit wet. I think I can get my air angle grinder with roll lock discs on most of the rusty areas.

[ZCurves]

Couldn't you get an angle-mirror and see what the condition under the battery tray really is? Then you could media/soda blast with one of those cheap kits from Harbor Freight. Treat with Phosphoric Acid, clean, prime and paint. I have a touch-up gun you can use.

[zKars]

Getting all that rust sealed is critical or you're just band-aiding and all your work you're doing now will soon be wasted when the rust comes back again. Short of sand blasting with a flexible hose held under the tray to completely strip it, there is no way you will clean it properly without removing it.

If the underside of the tray is nasty, then the areas between the tray flanges and fenderwell at the spot weld areas are also nasty, which you can't get to without removing the tray (spot weld drilling).

I know its hard to judge just how bad this is, but I've seen too many that were far worse than externally visible, including what happens below the tray into the frame rail and firewall. Until you've thoroughly stripped the area, its not possible tell the true extent of the damage. Its better and easier with everything out to fix this properly now than later. Been there done that.

I've erred too many times with this issue on the side of "oh its just surface rust" that came back to bite me. Sorry for taking the hard line on this, but "do it right" has to win in this case. You're car is too nice to just patch over the rust.

Edited October 2, 2012 by zKars

[hls30.com]

After doing all of the typical things in other Zs and having rust in that area come back, I drilled the spot welds to remove the tray, replaced the underlying metal and welded it back in-not difficult, no real muss or fuss, and more importantly I touched it once and was through. I did use POR15 products to seal the replaced/repairied metal.

There are only a few spotwelds...after I figured that out it just didn't make sense to "try" to take care of it-so I actually took care of it.