Thread: battery corrosion

Hi, the white powder is not uncommon these days. It is basically liquid battery acid that has leached around the seals for the battery terminals and vent/filler caps, and dried after the water content has evaporated. The powder can be highly corrosive if it comes into contact with water, (even from fog), and will damage the battery lead terminals, battery carrier, and any other metal it comes in contact with.

The best way to fix the problem is to regularly wash the lead terminals, battery case, carrier, clamps, etc with a strong solution of warm to hot water and bicarb soda. The bicarb will react with the acid and fizz and bubble, this reaction neutralises the acid, and leaves a salt residue. Once you can apply the solution to any part without reaction, you have then neutralised all of the acid on that part, and you should then wash the part with warm water and detergent and a scrubbing brush to remove any salt deposits.

If you find bare rusty metal that has been attacked by the acid, neutralise it with bicarb solution, wash, allow to dry, apply a rust neutraliser to convert the rust (unstable oxide) to a stable oxide, then apply a couple of coats of bitumous paint for ongoing protection. Bit paint is one of the few coatings that are fairly impervious to sulphuric acid.

It would be most unlikely that the acid powder formation would affect the warm up cycle of the motor unless the acid has built up to such an extent that it has been able to attack the wiring harness, sensors, or computer systems.

If the car is hard to start from cold and then rough till it warms up, suspect the 'enrichment system' which replaces the old carby choke system. This senses engine operating temp and adds extra fuel to the mixture as required until the engine warms up. The extra fuel can be supplied through the normal injectors by adjusting their open period, or via a seperate 'cold start' injector common to all cylinders.

If the car starts fairly easily from cold, but is a beast during warm up, suspect the temperature sensors, rather than the injector side of the system.

malb's on the money.

After cleaning the terminals it is usual to cover the terminals with petroleum jelly to prevent further corrosion.

Originally Posted by malb

Hi, the white powder is not uncommon these days. It is basically liquid battery acid that has leached around the seals for the battery terminals and vent/filler caps, and dried after the water content has evaporated. The powder can be highly corrosive if it comes into contact with water, (even from fog), and will damage the battery lead terminals, battery carrier, and any other metal it comes in contact with.

The white stuff is actually not just dried acid but a mix of Zinc, Lead and copper sulphates and extra acid formed by the reaction of the battery acid with the battery terminal and clamp and sometimes the battery compartment. If the terminal clamps have iron or an iron bolt/screw in or near them there will be iron sulphate as well. As malb says the stuff is corrosive and he does a great job explaining how to get rid of it.

The other thing you can put on it is the black stuff they paint on horses hooves, Cant remember the name, but someone will know it. Cheap and will protect the terminals.

woodcutta

Thank you so much to everyone for your informative and detailed responses.
My husband has spent the last hour replacing the 'cold start injector' from a spare 929 and he thinks he saw water in the fuel. As the fuel ,tank is just about empty he is now draining it to see if that could have also been affecting the performance.
We love these oldish (1992) Mazdas and it's great having a spare on hand. It's saved us a heap of money and even though hubby is not a trained mechanic he is having a heap of fun.
It's great having the info on the battery and he will attend to it ASAP.
He will also look at the 'performance' area.
Kind regards,
JMJ

PS
Yes it is a beast until it warms up. We usally just grit our teeth through it, so we will definitely be checking the 'temperature' situation.
Cheers,
JMJ

Get yourself a Haynes manual for the cars, and perhaps a fuel injection book. I used to have a BoschF.I. book that was great reference for Fl systems, including the Japanese ones, which operate (obviously) on the same principles.

Also, google and ebay are your friend for troubleshooting/parts.

(I needed a new distributor last year for an old Accord, dealer here $1200. Dealer in L.A. $60.00. Same part, better service.)

I don't have any specific insights into your cold running difficulties, but agree completely with the foregoing on the battery terminal condition.

Good luck...

Sounds like a tuning problem of some kind possibly fuel . It mostlikely also needs some new parts in the electrical ignition system .

If you suspect water in the fuel, it will affect the flow through the filter so a new filter may be needed.

A temporary solution to moderate water contamination in the tank is to add some metho to the tank contents. Metho is hygroscopic (absorbs water) and allows the residual water to flow through filters, injectors etc to clear the system. One cup of metho will cope with a cup of water in the fuel mix, enough to clog a number of filters.

I also use metho as a basic rinse and final rinse if I need to drop a tank because of recurring contamination. If the problem is reccurring, drain and drop the tank and look for the source, it is normally damage to the tank or seals. Check the tank seams and filler sealling etc, particularly if the tank is partly behind a wheel and exposed to water spray from wet roads.