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MG MGA - Possible Starter Trouble

I have checked through the archives and I think I have a starter problem, but I'm not entirely sure where to go next or what the problem might be.

My car is 12V, negative ground, electronic ignition.

Senerio seems common.

I started the car Saturday, same as I do almost everyday and things were fine. I went to a friends house and when we were ready to leave I pull the starter and nothing. No sound, nothing.

Battery checked out OK, but was 8 years old so I replaced it. Still nothing. At the switch under the bonnet I get 11.85 volts, should be enough.

If the car is roll started it runs fine.

Now the odd part. After I replaced the battery and got nothing I roll started the car. I backed it up the drive and checked the generator (OK) and turned the car off. When I tried to start it again it fired right up.

I got home and went to leave later that night and nothing again.

Finally after looking at all the electrical stuff again I was checking the connection to the starter and out of desperation I turned the square bit on the front of the starter. It moved the motor freely.

Guess what? After that the car fired right up.

So far it has started everytime and I cannot duplicate the problem.

Anybody got any ideas?

I do have a spare starter, but if anyone havs any ideas, I'd love to repair this one, or perhaps it only needs a good cleaning. It is hard to say since I don't know what is actually causing my intermitant problem.

Thanks,
Christopher
'62 MGA
Christopher Wilson

Your car needs 12v to start, not 11.85. A lower voltage can allow your car to run but not start as under LOAD when you pull the starter. Your starter may have a dead spot on the armature which is why it did not turn over. You can put 12v directly to starter with jumper cables to see it spin and if it does, you may have a bad silonoid. Also have your battery put under a load test to see if it holds at least 12v or will it crap out
JEFF BECKER

When you check voltage at the switch and get 11.85, is that with the switch open and reading directly off the battery, or with the switch closed and reading the load off the starter motor? I think you have one of two scenarios:

Most likely: Your starter pinion and ring gear are binding. When this happens, as it has happened to me, you may get no noise from the starter or any other indication when you pull the switch. The lights may dim as you are putting a load on the system, which is why I asked when you were getting the 11.85 volts. This would explain why it starts after you mechanically free it i.e. a wrench or popping the clutch. Use the wrench technique or easier put the car in 1st and rock it back and forth till the bendix pops free.

Less likely: You have a bad ground. Check the battery terminals, negative termninal to chassis cable, and engine ground strap. If there's a lot of corrosion or many broken strands then other electrical systems may work but when you put a heavy load on it like the starter there's too much resistance.

I'm betting on the first scenario but I've seen both before. You may get away with just replacing the starter or pinion gear, but be aware that your ring gear may be too far gone and will end up chewing up any new starters you put in there.

Mark
Mark J Michalak

Mark, I think senerio 1 is the possible issue here. Is there any way to tell if the ring gear is bad without pulling the engine?

Will there or should there be an indication of wear on the starter pinion when I pull the starter?

Thanks,
-Christopher
Christopher Wilson

Christopher

One other thing to check is a sticking or worn brush in the starter. Sticking brushes can occasionally "hang up" so that contact is not made. A brush that is badly worn may also not always make contact with the armature.

FWIW

Larry
58A
Larry Hallanger

When you pull the starter you can see the ring gear. have a friend turn the engine with the hand start crank while you inspect the gear. The engine tends to stop in one place the majority of the time so the wear will be concentrated on about 4 teeth at that point. If you can't find the worn spot it is probaly OK.
R J Brown

Hey folks, thanks for all the support on this one.

It was the starter motor. I changed it last night, my spare works fine.

The ring gear is OK and it was the brushes in the motor itself that apper to be bad, that coupled with the fact the inside of the motor was extremely dirty. I'm not sure how that would happen but it was.

I guess that was a good life for the original starter though.

Thanks again,
Christopher
Christopher Wilson

This thread was discussed between 01/10/2007 and 03/10/2007

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This thread is from the archive. The Live MG MGA BBS is active now.