QuestionQUESTION: In 2005 I restored an mg midget 1500 (w reg) for my wife, the car has since only done 1200 miles when the sun is shining which is not very often in this country.The rest of the time it stands in the garage with a protective cover over it,when it was first finished I replaced te old battery with a new one,the car started first time and off we went enjoying the fresh-air.however since then and another new battery later the damn thing will not start at all now without the use of jump-leads,when it is running it will go all day and sart all day,but when you put it back in garage and go to it the following day the battery seemd to be dead as it will not even turn the engine over,I have changed the starter and the alternator but it has not made a blind bit of difference,I am at my whits-end and now the wife is talking of getting rid of the car because it won"t start when we want to use it.
Can you help or advise at all.
ANSWER: Hi Andrew,
This should be a simple problem to correct. Since it starts with a jumper battery all you need to do is to first charge the battery fully and then do a simple test. With the battery fully charged put a volt meter across the posts of the battery and read battery voltage. Then start the engine and set the idle at a fast idle (1200 to 1500 RPM) and read the voltmeter. It should read 13.8 to 14.5 volts. Now shut the engine down and remove one battery cable and take a 12v test light and connect the light between the loose cable and the battery post you removed it from. Check that nothing electrical is turn on and note if the test light is on. If the test light is on you have a battery drain of some kind and that will require a wiring diagram and tsting of the circuits for the drain. Let me know if you have a light and I will walk you through the tests.
If you had aprox. 14v on the fast idle test and no light of the test light test, than you must evaluate how long you let the car sit between start ups. If it is longer than a week you should consider one of the low amp chargers that keep a battey up but will cut back automaticaly when the battery is up. Most motorcycle dealers handle these chargers. If the test light was not on and the charge rate was 14v and the battery will not start the car in a week, you simply have a bad battery. I hope this helps, let me know.
Howard
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QUESTION: HI Howard,since our first corrsepondence things have gone from bad to worse.I charged both batts until they both were 14-14.8 volts,put one on the car and tried to start,nothing,just a loud clicking around the starter soleniod area,checked all connections on the solenoid and found the small lower one to be loose.thinking this may be the problem I went to my local MG centre ( welsh mg centre -Rhostyllen,Wrexham to see Phil who was very helpful when I was restoring the car in the beginning )and bought a new one,put it on the car and it was just the same,click,I also fouund after a lot of swearing at the damn thing that the starter lead on the starter would move although the connection was tight,removed the nut from the lead and retightened the inside nut until the stud would not move reconnected and retried,nothing just the same ,click.I think I may have found the leakage of power however after borrowing a fluke meter from an electrician in work I found that with all the fuses removed from the fuse box THE FRONT SIDE,HEAD AND MAIN BEAM LIGHTS ALL CAME ON.This is seriously not right is it.I have since tried to jump start the car and all that happens is the same CLICK. I AM STARTING TO LOSE MY PATIENCE NOW any ideas or thoughts would be helpful
Andrew.
ANSWER: There are two large posts on the solenoid, did you never check to see if voltage was transferred to the second post when the solenoid went "click"? Also, does the engine turn over freely by hand?
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QUESTION: Yes, I checked for the voltage transfer on the old one and the new one,there was no voltage on lower post when it went "click". Yes the engine will turn freely by hand.
Andrew.
AnswerHi Andrew,
The starter solenoid has two functions. One is to connect the battery to the starter motor and to connect the small gear on the starter to the flywheel ringgear. This is done by two electro magnets inside the solenoid. The first magnet is to make the first move which connects the two large posts together (battery post to the motor post) and at the same time slide the small gear (starter bendix)out to connect to the ring gear. The second (light duty) magnet is activated when the solenoid piston reaches the end of its' travel. (this is the "click" you hear)The first strong magnet is disconnected and the second light duty magnet takes over to just hold the piston in place.
The battery is connected to one of the large post at all times. There is a third small connection on the solenoid and that is the magnet wire. It is powered either by an ignition switch or a starter relay when the key is turned to start.
Knowing how a system works allows you to simply diagnose a problem. First, is there power to the battery post? (You checked that and there was) Second, is power getting to the small lead that operates the magnet? The "Click" you hear tells you there is. Third, Is the solenoid connecting the battery lead to the starter motor. (This is tested by connecting a test light to the "other" large post at the time the solenoid is activated) If NO, the solenoid has failed. If YES and the starter didn't turn, then the starter motor is bad.
This is the basic design of all automotive starter systems so once you know this you can diagnose most car starter systems. Let me know how you do.
Howard
