rusty battery box repair recommendations
 

Hi All,

Looking for some expert (well, at least more knowledgable than me) advice.

Like all 944s, mine has developed rust and at least one small hole in the battery tray. I repaired this a couple years ago but the seam sealer I used has cracked and let water underneath. :bang:

One area (~3"x3") feels pretty thin and has at least 1 (that I've found) tiny hole thru to the passenger footwell (where the DME lives). I've started using a sealed Odyssey battery so battery acid damage is a thing of the past.

A couple repair options that I'm considering after cleaning the rust are:
1) smear sealer over the area and paint (using POR)
2) just paint (POR) over it
3) tack weld a piece of sheet metal over the worst area, seal, and paint
4) seam weld sheet metal over the area, seal, and paint (least desirable option as there are sensitive components like the airbag controller immediately under the tray)

Any advice? Any recommendations on a good seam sealer? Anyone used the 'POR Patch' seam filler found on their website?

Chris has some excellent info in his thread about some amazing acid proof paint specifically for battery boxes! :D :D

Seriously....One thing you didn't mention was if it is structurally sound. It has been a while since I looked at your car, but I seem to recall the (small) battery having a good solid mount. If the structure is weak enough that its ability to anchor the battery is in question then a proper weld-in structural fix is in order. If this is purely cosmetic and for water proofing, then I'd say the seam sealer and paint fix is plenty. If you "tack" weld any metal in place you must be certain it is fully sealed or you will just make a rust sandwich that will get much worse in time. Another option for a non-structural fix is to properly sand/prep the area and then fiberglass some cloth over the holes before a final painting.

Eastwood and Auto Body Toolmart should both have the sealers, etc. you may need.
http://www.autobodytoolmart.com/
http://www.eastwoodco.com/

I just went through all of this. If I were you, I would not waste your time with just sealing it up with anything.

Cut and weld. Put new metal in their and give yourself something strong to which you can mount the battery/kill switch, etc. . .

The only thing to watch is drainage. When my car is on the trailer, it can collect water in the rewelded tray. I am about to cut a drain on the backside for this reason.

Good luck.

Not a structural issue. The thin area is close to the firewall and along the seam joining the firewall so attachment of the battery on either side is fine.

As the car is either in the garage (winter position) or covered (summer position, parked slightly uphill), it only sees water at track events or the occasional washing.

TD, you obviously haven't seen my fabrication skills. Andy has, which is why he recommended filling. :cry:

I might try to build up that area w/ filler to avoid the situation you describe (which is likely why mine is rusting in that area as well).

I don't have a welder either. It didn't cost much to have a body shop weld in new metal there, or one of the Dorki with a welder could probably do it for you easily. I just think it will be a better fix for less time/money.

This just seems to me like one of those kinds of fixes where you can either do it right the first time, or spend a fair bit of time with a compromise fix, that you then have to redo in about 6 months or 1 year.

Just make sure that you put a drainage hole back in after it is fixed ;)