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Battery acid / paint damage / Negative cable oxidised


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Battery acid / paint damage / Negative cable oxidised

Obligitory I f***ed up and now i'm paying for it.

A year back i went interstate for about 3.5 months and left my car in a mates back yard with a tarp over it.

I'd left a lead acid battery connected thinking that i'd just jump start it when i got back.

Came back and i had a big star shape of rust under the bonnet above the battery and further surface rust below the battery area. Wonderful.


Fast forward a bit, change of address and saved some cash,  and firstly, can't find a competent person that can actually tackle this engine bay damage properly, and neutralise whatever the hell it is on the paintwork. I am assuming it is battery acid/vapor damage but i have no idea what happened.

I've paid a bloke 900$ in Dandenong (Vic) to crack at it and all his paint is just bubbling up and peeling off again. On their warranty card it says they don't cover rust and he doesn't want anything further to do with it particularly.

I've put a brand new lead acid from repco in there and the thing worked for about two weeks and now it won't hold a charge at all. Alternator is giving me 14.4 when i jump it, fortunately i had the alternator reconditioned only 20,000 km's ago.

I've noticed some oxidisation on that main negative lead thats soldered and screwed to the chassis but unsure if this can prevent a battery from charging.

At the end of the day, i think i've got f**ked battery and it has been leaking down its back all over my engine bay again, no idea why, it's 5 weeks old. I plan to replace

it with a dry battery if i can find one that fits.

I'll note that on this R34 the battery compartment was really tight and i pulled out a white tray that used to be under the battery. Is it neccesary or no? I know for example

my Falcon has its own plastic surround for cooling. This one On the R34 is just sitting on the chassis held with a clamp.


Questions i suppose, recommend a type of dry battery thats correct for 34 Gtt?

Can a bad negative connection prevent a battery from charging?

Why do these lead acid batteries keep freaking bubbling over ( amplified sound system in car too much strain?)

Know someone in vic that knows how to tackle rust/acid or an auto elec familiar with fault finding electrics in skylines.


Thanks for your time. I'm aware i f***ed up. cheers





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If your tray is Ok and its just surface rust, I would go and buy some steel and brass brushes, plus some emery paper, and a brush for the 4" angle grinder and hit it hard.

Then I would buy some rust convertor/removal, probably in the gel format for your job and apply it and let it eat the rust away then hose off and dry immediately.

Get it nice and clean and dry!!!

I would then apply rust resistant paint undercoat and cover it. What you use for a topcoat is up to you.

While your at it, use the wire brushes, undo your earth strap and clean it up as well.  When re installing don't paint it etc, just leave it bare, except for a spray of CRC yellow contact or a smear of dielectric grease or Vaseline.

I personally wouldn't use a vented battery ever again.  Sealed batteries all the way IMO.

$900, you can do this for $200 and do a better job of it.

You probably need to check the voltage and amperage output of your alternator...could be that your regulator isn't working and the battery is being overcharged???


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Damn man, how much battery acid leaked? I ran my battery on 15.3 volts for half an hour and it started to leak. How did the battery acid react to your metal in the engine bay? Below the batter tray mine is white and and the railing by the battery it is white now cause it lost the paint. If a simple sand down, followed by primer and paint enough to fix this issue? youre kinda scaring me now lol. Its only been a week since it happened

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Thanks for the input.

Im32fk -  I don't know exactly what happened. Clearly the water in the batteries is nasty and if that drips down its caused the issues under, but i dont understand how its ended up on the bonnet above. The car was left under a tarp and it was very damp out, but the paintwork on this car has always been good. I don't think i'll ever know exactly what caused it.

I do not believe simply sanding it down is enough, to answer your question. The spray painter resprayed my bonnet and sanded back and bogged it 3x before it finally settled.

However I believe after sanding it back as suggested you massage some diluted Bi-Carb soda into the damage that might do the trick. Others might know better though. This is what i'll be trying to do.

Tridentt - thanks for your ideas. It is just surface at this point, just in an awkward spot, particularly on that rail near the engine. God damnit.

My Alternator is giving me a beautiful 14.3 volts, what i have found is that my spray painter has painted the rail and underneath the main negative leads clamp to the frame, so the clamp had a bad earth. I'm not experienced with DC systems but i believe squeezing 14.3 into the battery and having a bad return path probably f**ks them pretty quickly.

I'll sand back underneath the main negative lead clamp and put in a new battery.

Related - i'm having big troubles trying to source a replacement lead. Any ideas on where i can get one?

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