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MG MGA - Starter ate my battery

Driving to work today I smell some unfamiliar smell.

Suddenly the engine dies. I try to start it and the starter wont move. Damn it! Roll down to the side to a car park to check what has happened.

It seems like the started cable had got slighly stuck-out enough to keep the starter motor in contact and drain the battery.
This happened within 5-10minutes of driving

I jump started it and it worked fine but the battery is obviously dead.
The was some white oxidation stuff on the positive terminal of the battery.
I am going to try to charge it tonight to see what happens.
Questions;
Has anyone had this happen to them?
Do you think the battery is fried?
Do you think the starter motor may be damaged? brushes or something else?

Thanks!
Gonzalo
Gonzalo Ramos

Gonzalo,
Yes, I had this happen. I was at the Seven Springs NAMGAR event (GT32?) I was taking the car for a test drive after some minor maintenance and heard an odd noise when stopped at a stop sign. I returned to the parking lot, shut the car off, and the noise continued. At first I could not understand where the noise was comming from. Then I noticed the starter cable was slightly pulled out. Pushed it in and the noise stopped. The starter was running, but slowly. Very weird. I did not run my battery down. I too was concerned about the starter, but that was nearly 3 years ago and starter and battery have been fine. I lubed the starter cable after that...:) Since your car started OK I suspect you starter will be fine although it sounds like your starter may have gotten rather hot. I would check the electrical wiring carefully. The battery should charge with no problem. The oxidation you discribe is pretty typical. I wouldn't be too worried but if you get the chance you might want to remove the starter, open it up and inspect it.
Cheers,
Gerry
G T Foster

Gonzalo, the white stuff on the teminal post is just lead sulphate. Hot water from your kettle will disolve it and wash it away, then apply petroleum jelly (Vaseline) to the teminal posts to stop it growing back. Your battery will almost certainly be OK, just give it a charge and check the electrolyte levels.
Lindsay Sampford

Thanks for that! I will check your suggestions and charge it tonite.
The worst thing is getting out of the traffic with a 'rolling car'.... ; 0
Gonzalo Ramos

I am NOT a fan of "then apply petroleum jelly (Vaseline)" Vaseline melts into the connection and helps INSULATE between the battery and the cable. I use NOTHING and keep it clean. Batteries like to be kept clean. A solid dry connection is what you want. I don't know how many cars I have seen come into my shop over the years with a poor connection at the battery caused by some slimy stuff there meant to protect it. Battery anti corrosion pads are a waste also. Causing more trouble than they solve.
R J Brown

I've always used it on my batteries to good effect. When I worked as a telephone exchange engineer, I maintained the twin 400aH 50v batteries that they ran on. Every one of the 200 connections for those two batteries was "Vaselined", it was in the Engineering Instructions.
Lindsay Sampford

I had to read thi several times to understand Gonzalo and Gerry are talking about the starter "switch" cable not returning fully. I'd recommend removing and cleaning the battery posts while you are in the cleaning up the corrosion. I had problems with battery corrosion on my Spitfire back in the early 70's.

Proper dielectric grease is better than Vaseline for battery terminals. Either is better than nothing at all. Just my experience. However, in practice, I don't use either for battery ternimals but know of its value. I do use dielectric grease on all of the bullet connectors.

I have used the anti corrosion pads for nigh-on 30 years on all my cars with MUCH (almost none) less corrosion than the first 10 years without. Nothing aproaching the crud buildup on the Spit. It might be just that battery post seals are much better these days, but having them there is a low cost, peace of mind sort of thing.

If you are still getting corrosion on the battery, then perhaps your battery post seals are bad or the charging circuit is set too high. Modern batteries don't want (or need) the high voltage that the original Buzz-Box MGA regulator is set for. Once setting the buzz-box, and using the pads, I had virtually no corrrosion buildup on my MGA in 10 years. It was litterally set it and forget it.

Chuck Schaefer

I took out the battery and charged it last night.

It seemed to charge up properly so I will install it tonight and take it for a ride.
Thanks for the advice. I will try some of vaseline to see what happens. I think it was the rapid discharge that caused that oxide formation cos the battery is normally clean.

BTW I had the car polished now after the paintjob and it looks amazing. Like a mirror!

Unfortunately the guy at the shop pushed down the bonnet too far and it got stuck! So I have a 'stuck bonnet latch saga' last night, but all is well now. I have also re-adjusted the bonnet pin (shorted) to prevent that from happening again.
Gonzalo Ramos

I own an auto repair shop and have for 30 years. I see problems with poor battery connections almost daily.
If you choose to put Vaseline on battery terminals do it after the connection is made. If you need to take the terminals loose you then have to clean all the grease off completely before re installing the cables.
Dielectric grease is made to put on connections and is a better choice if you insist on greasing you battery. My personal experience has shown it to be a poor practice. It causes more problems than it prevents. Clean and Dry are the important considerations.
At best it is just messy. All Vaseline does is cover a problem than should be addressed directly. Acid usually builds up for one of 3 causes. #1 over voltage that causes gassing. #2 Too much resistance in the battery itself causing gassing. #3 a broken seal between the post and the case that creates an acid leak. Usually caused by being too rough with the terminal, twisting motion while tightening or loosening the terminal.
This is one of what I consider a useless "old wives tales" type or repair. Save yourself the hassle and just say NO.
R J Brown

I use a product called DURITE which is an Ant-Corrosive Compound that claims to kill corrosion & inhibits deterioration of terminals & metal parts on or near lead acid batteries.
As mentioned by R J Brown, I always apply this after the connection is made.

Richard
R A Evans

For years I have used OMC triple guard grease applied sparingly inside and out and have never had corrosion or a dead battery.
Richard Taylor TD3983

Corrosion is caused by the reaction of the sulfuric acid that produce hydrogen inside the battery during the chemical process of the electrolysis, the hydrogen escapes from the battery cap and react in the posts and connectors of the battery, in addition when using different materials, (post-terminal-bolts-nuts) lead-steel-bronze used may aggravate the corrosion, grease dirt, dust, make a worst condition.
the corrosion increase the resistance between conductors (connections) affecting the conductivity, so, the charging process may be null, for that reason the engine will be dead as long as the battery.
Preventive maintenance is suggested, cleaning the connections, or washing it with baking soda and water when the corrosion is already there, once the components are dried and cleaned, assembly and spray it with a protective solution for battery terminals, any auto parts store have it.
R Garcia

The story continues!

So I put the fully charged battery back in and tried to start the car.
The starter motor turned VERY slowly, however the engine eventually started.
I thought that was strange. Then I turned it off and tried again, and this time it was a bit faster.
I tried several times after with the same result. The car starts but this to me is indication of an issue somewhere.


NOW, my thinking is;

1. The battery got damaged, so it couldn't charge as much. However the charger indicated full charge and no problems.

2. the starter motor go damaged? (brushes or contacts)

3. The battery posts are not making good contact; hence high resistance.

4. The grounding or wiring on the starter motor got hot and maybe go damaged. Maybe the live wire it is slightly touching ground somewhere?

What are your thoughts? How can I best test for these conditions?

thanks,
Gonzalo
Gonzalo Ramos

Gonzalo you already mentioned what may be the causes of your problem. Just check each of it.
There is no wiring for grounding the start, it is connected directly to the body with the mounting
screws.
R Garcia

A battery can show "fully charged" on the charger, but can still be broken, i.e., it can't handle the load. A battery shop can check this for you.
Also check the date on the battery - if it is 5 or more years old, it is due for replacement.
The fact that the starter did eventually turn fast ands started the car, suggests that it is OK. But all connections should be checked - those on the battery, those on the starter, and those on the starter switch. Check for cleanliness and tightness.
Peter.
P. Tilbury

Starter is not connected to body or chassis of the car, it is grounded on the engine rear plate. The engine in turn sits on rubber mounts electrically isolated from the chassis. To make the starter work the engine must be grounded to the chassis. This is normally done with a short section of bare braided grounding cable connected across the left side engine mount from engine to frame. If this cable is missing the starting current will be trying to find some alternate path to chassis ground. This commonly goes through metal control cables like the choke cable or heater valve control cable. Those conductors are not large enough to carry the full cranking current, so the starter will be very slow if it turns at all.

To check for proper engine grounding use a volt meter. Connect one test lead to the starter motor case or mounting plate or engine block. Connect the other test lead the the frame of the car. Crank on the starter. If you see anything more than 1/4 volt (250 milli-volts) volts on the volt meter when cranking you have bad engine ground.
Barney Gaylord

Also put the voltmeter across the battery. If it is in good shape you should get a reading in excess of 12 volts.
G Goeppner

This thread was discussed between 28/02/2011 and 07/03/2011

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