MGB - dodgy starter motor or battery?
Discussion
This is my first winter with the B... and it's been interesting.
I'm a self-confessed technical numpty... I love cars... I've just never bothered to see how they work before (until now...) so please forgive my ignorance if I say something particularly dense!
Thanks to a dodgy coil at the beginning of December - I managed to flatten the batteries somewhat by turning the engine over for a bit too long... got the coil sorted out and got her going with a booster pack. Took the B out for a couple of hours to top the batteries back up and the next time I went to start her (about a week later) she was very reluctant and turned over very slowly - again the booster pack helped to turn her over.
A couple of weeks ago I invested in a battery charger (with a built-in tester) as I though that the batteries were probably in need of a good charge... connected the charger up to them and it said that they were fine - 100% charged... it had a trickle-charge function so I left it on for 4 hours or so for good measure. Tried turning the B over and again... very stubborn and slow to turn over (yet again the booster pack did it's job).
I'm a bit confused now... is it that the batteries are shagged? They were brand-new in the summer... so I'm quite surprised - or could it be a dodgy starter? It looks pretty old and I hear that the high torque units are much better anyway.
Any suggestion/advice is very welcome!
Cheers,
Ant
I'm a self-confessed technical numpty... I love cars... I've just never bothered to see how they work before (until now...) so please forgive my ignorance if I say something particularly dense!
Thanks to a dodgy coil at the beginning of December - I managed to flatten the batteries somewhat by turning the engine over for a bit too long... got the coil sorted out and got her going with a booster pack. Took the B out for a couple of hours to top the batteries back up and the next time I went to start her (about a week later) she was very reluctant and turned over very slowly - again the booster pack helped to turn her over.
A couple of weeks ago I invested in a battery charger (with a built-in tester) as I though that the batteries were probably in need of a good charge... connected the charger up to them and it said that they were fine - 100% charged... it had a trickle-charge function so I left it on for 4 hours or so for good measure. Tried turning the B over and again... very stubborn and slow to turn over (yet again the booster pack did it's job).
I'm a bit confused now... is it that the batteries are shagged? They were brand-new in the summer... so I'm quite surprised - or could it be a dodgy starter? It looks pretty old and I hear that the high torque units are much better anyway.
Any suggestion/advice is very welcome!
Cheers,
Ant
Check the battery terminals and the earth on the body.
Check the connections at the starter motor.
Does yours have a inretia type starter or pre engage?
Look at the atarter.
Is therea second, smaller cylinder on top?
Probably has 2 wires to the Pre engage type. One large battery feed and a smaller switching wire.
If not you will have a seperate solinoid on the car.
Check the wires on the solinoid too.
All connections should be clean and tight.
Might be worth checking the charging rate as if the alternator is duff it will not charge the batteries.
Check the connections at the starter motor.
Does yours have a inretia type starter or pre engage?
Look at the atarter.
Is therea second, smaller cylinder on top?
Probably has 2 wires to the Pre engage type. One large battery feed and a smaller switching wire.
If not you will have a seperate solinoid on the car.
Check the wires on the solinoid too.
All connections should be clean and tight.
Might be worth checking the charging rate as if the alternator is duff it will not charge the batteries.
Pre engage has a second cylinder sat on the top.
The wires go to the second,smaller cylinder on 2 connectors.
A larger one which will be constant 12 volts and a smaller wire on a second push of terminal, which will only have 12v when the key is on the crank position
Inertia starter is just cylinderical and will probably have just 1 connector with a thread holding the large wire on.
The wires go to the second,smaller cylinder on 2 connectors.
A larger one which will be constant 12 volts and a smaller wire on a second push of terminal, which will only have 12v when the key is on the crank position
Inertia starter is just cylinderical and will probably have just 1 connector with a thread holding the large wire on.
I've checked through all the connections and they look fine... engine earth strap is ok too.
The starter is a bit of a bugger to get to though... is it best to remove the distributor and the oil filter to get to it?
The thing that puzzles me though is why will the car turn over better and fire up with a booster pack attached to the batteries... can a failing starter draw more power?
The starter is a bit of a bugger to get to though... is it best to remove the distributor and the oil filter to get to it?
The thing that puzzles me though is why will the car turn over better and fire up with a booster pack attached to the batteries... can a failing starter draw more power?
pantscat said:
I've checked through all the connections and they look fine... engine earth strap is ok too.
The starter is a bit of a bugger to get to though... is it best to remove the distributor and the oil filter to get to it?
The thing that puzzles me though is why will the car turn over better and fire up with a booster pack attached to the batteries... can a failing starter draw more power?
It can do.The starter is a bit of a bugger to get to though... is it best to remove the distributor and the oil filter to get to it?
The thing that puzzles me though is why will the car turn over better and fire up with a booster pack attached to the batteries... can a failing starter draw more power?
Did you check the voltage at the batteries with the engine running?
In the good old days you could strip and overhaul a starter motor.
You could replace the brushes in the motor, clean the armature etc.
I doubt you would get the parts today.
pantscat said:
I've checked through all the connections and they look fine... engine earth strap is ok too.
The starter is a bit of a bugger to get to though... is it best to remove the distributor and the oil filter to get to it?
The thing that puzzles me though is why will the car turn over better and fire up with a booster pack attached to the batteries... can a failing starter draw more power?
The easiest way to get to the starter is from underneath the car, where you can get straight at it from the drivers side.The starter is a bit of a bugger to get to though... is it best to remove the distributor and the oil filter to get to it?
The thing that puzzles me though is why will the car turn over better and fire up with a booster pack attached to the batteries... can a failing starter draw more power?
If the car isn't starting easily, have you changed / adjusted points, dizzy cap, condenser at all? Agree that your battery should be holding its charge better, but if the ignition system is a bit old it won't help it. It did sound like your starter motor was turning over, and the B isn't that bad for starting....
wadgebeast said:
The easiest way to get to the starter is from underneath the car, where you can get straight at it from the drivers side.
Ahh... yes... sometimes I can be quite dim. That's a good idea.wadgebeast said:
If the car isn't starting easily, have you changed / adjusted points, dizzy cap, condenser at all? Agree that your battery should be holding its charge better, but if the ignition system is a bit old it won't help it. It did sound like your starter motor was turning over, and the B isn't that bad for starting....
It had new points/dizzy/condenser all in the summer... and before the problem in december it would fire up quite happily. The starter does turn... just very slowly and then will eventually stop.I need to get a multimeter on the battery posts and see what the reading is - am I right in thinking that a fully-charged battery (batteries...) will be reading about 13v?
Ta,
Ant
Here's what you need to do.
1: Get the engine running and check the alternator/dynamo output across the battery terminals. If yours is the twin 6v batteries then obviously connect between main positive and negative not just across battery terminals, if 12v its obviously easier. You should with engine running be getting about 14v ish. if it is 12v ish then your not charging the batteries properly hence the problem.
2: If above is ok, remove earth leads from body (battery to body) and emery up the surface, same on body. Make the connection good. Do the same on starter motor wire.
3: Find earth strap (if it is even there) it will be between bellhousing (bottom) and chassis leg usually. Again clean up till shiny and making good earth and try again.
4: Now the system is all good except starter or batteries. The problem you have sounds far more like batteries than starter, how old are they? If the charger is saying 100% charge and they are struggling that is a classic example of knacked batteries. Get along to motor accessory shop/mechanic and ask them to check with a battery tester, this will put a big load (much bigger than a multi meter you can't test this at home) and find out how they hold power, I think you'll find they will have very little life.
5: However if it is the starter then it is an easy job to remove and change, work from underneath and above, you need a 1/2" drive rachet and socket set with a long extension for the top bolt, and no extension from memory for the bottom. 9/16ths from memory you will need a spanner too. Then undo terminals from solenoid and lift out through engine bay (or I think it will drop out underneath too) it can be tested with a known good battery and a pair of jump leads, neg to starter body, positive to starter(not solenoid) positive (the post on the back of it) it should kick and spin fast. N.B. you can also test the solenoid with this process but yours is obviously fine. I'll be surprised if it is starter.
1: Get the engine running and check the alternator/dynamo output across the battery terminals. If yours is the twin 6v batteries then obviously connect between main positive and negative not just across battery terminals, if 12v its obviously easier. You should with engine running be getting about 14v ish. if it is 12v ish then your not charging the batteries properly hence the problem.
2: If above is ok, remove earth leads from body (battery to body) and emery up the surface, same on body. Make the connection good. Do the same on starter motor wire.
3: Find earth strap (if it is even there) it will be between bellhousing (bottom) and chassis leg usually. Again clean up till shiny and making good earth and try again.
4: Now the system is all good except starter or batteries. The problem you have sounds far more like batteries than starter, how old are they? If the charger is saying 100% charge and they are struggling that is a classic example of knacked batteries. Get along to motor accessory shop/mechanic and ask them to check with a battery tester, this will put a big load (much bigger than a multi meter you can't test this at home) and find out how they hold power, I think you'll find they will have very little life.
5: However if it is the starter then it is an easy job to remove and change, work from underneath and above, you need a 1/2" drive rachet and socket set with a long extension for the top bolt, and no extension from memory for the bottom. 9/16ths from memory you will need a spanner too. Then undo terminals from solenoid and lift out through engine bay (or I think it will drop out underneath too) it can be tested with a known good battery and a pair of jump leads, neg to starter body, positive to starter(not solenoid) positive (the post on the back of it) it should kick and spin fast. N.B. you can also test the solenoid with this process but yours is obviously fine. I'll be surprised if it is starter.
Cheers Oliver.
One quick question - how do I tell that the earth strap is making a good earth? I'm guessing with the multimeter... but I don't know how!
I was led to believe that the batteries were new in the summer... but I could be wrong! I'll have a hunt through the receipts and see if I can find anything.
Ta,
Ant
One quick question - how do I tell that the earth strap is making a good earth? I'm guessing with the multimeter... but I don't know how!
I was led to believe that the batteries were new in the summer... but I could be wrong! I'll have a hunt through the receipts and see if I can find anything.
Ta,
Ant
Quite often find that the earth strap is corroded at both ends due to the poor location of the battery box viz ingress of salt and mud. On my car the strap had actually broken due to the amount of movement that the battery made while I flung the car around in an enthusiastic manner. Drilled a new hole for the earth strap and placed a block of wood in the battery box. Had no further problems after that.
PS Don't forget to disconnect the battery if you're replacing the starter motor. I completely forgot the last time and nearly shat myself as it shorted out when I removed the old one. It's an easy job - 45 mins tops if you've got a pair of axle stands to work under the car safely.
PS Don't forget to disconnect the battery if you're replacing the starter motor. I completely forgot the last time and nearly shat myself as it shorted out when I removed the old one. It's an easy job - 45 mins tops if you've got a pair of axle stands to work under the car safely.
wildoliver said:
Here's what you need to do.
1: Get the engine running and check the alternator/dynamo output across the battery terminals. If yours is the twin 6v batteries then obviously connect between main positive and negative not just across battery terminals, if 12v its obviously easier. You should with engine running be getting about 14v ish. if it is 12v ish then your not charging the batteries properly hence the problem.
Just about had enough light just now to check the voltage across the main terminals and it measures at about 12.25v. One battery on it's own measured 6.25 and the other was 6v.1: Get the engine running and check the alternator/dynamo output across the battery terminals. If yours is the twin 6v batteries then obviously connect between main positive and negative not just across battery terminals, if 12v its obviously easier. You should with engine running be getting about 14v ish. if it is 12v ish then your not charging the batteries properly hence the problem.
Didn't get her started as I've forgotten to charge the booster pack - but I did measure the voltage during cranking and it dropped to 4-ish volts... that seems very low... but does it indicate one or more duff batteries?
At the weekend I'll make a start on checking all the terminals... doesn't look like I'm going to have a day working at home!
I've just had a very fun afternoon cleaning up all the terminals. The batteries have been on trickle charge for most of the day too.
Put everything back as it should be and after a bit of hesitation - the B lives!
Cheers for all the good advice... very much appreciated.
I think a new alternator is in order though - when she's idling there's only 13.4v across the battery posts - should be more like 14 - 15v shouldn't it?
Cheers again... I'm off out!
Ant
Put everything back as it should be and after a bit of hesitation - the B lives!
Cheers for all the good advice... very much appreciated.
I think a new alternator is in order though - when she's idling there's only 13.4v across the battery posts - should be more like 14 - 15v shouldn't it?
Cheers again... I'm off out!
Ant
I'll keep this short as I've just lost all that I typed
Sorry to come in late
As a person that used a BGT for everyday use, work and tours - change all your battery leads and engine earth lead for new - make sure all battery and lead terminals are clean and protect with something like Copper-Eaze before fitting these new leads
You've already experienced what a pain a non-starting car is so you'll know the monetary cost of replacing these leads will be worthwhile
If you wanted to, if you look around enough it is possible to get one suitable 12v battery to fit in where one of the 6v sits (or was when a mate done it a few years ago) thus getting rid of one of the problems of the lead between the batteries and its resistance
The batteries are very exposed to road dirt so replace broken plastic boxes
Oh and make sure the fliud level in the batteries is correct before and after charging up - an ederly neighbour of mine used a battery charger on his car so often that he must have almosted fried it before I got to see it but I topped up the fluid level and recharged it and surprisingly the battery lasted another few years
Sorry to come in late
As a person that used a BGT for everyday use, work and tours - change all your battery leads and engine earth lead for new - make sure all battery and lead terminals are clean and protect with something like Copper-Eaze before fitting these new leads
You've already experienced what a pain a non-starting car is so you'll know the monetary cost of replacing these leads will be worthwhile
If you wanted to, if you look around enough it is possible to get one suitable 12v battery to fit in where one of the 6v sits (or was when a mate done it a few years ago) thus getting rid of one of the problems of the lead between the batteries and its resistance
The batteries are very exposed to road dirt so replace broken plastic boxes
Oh and make sure the fliud level in the batteries is correct before and after charging up - an ederly neighbour of mine used a battery charger on his car so often that he must have almosted fried it before I got to see it but I topped up the fluid level and recharged it and surprisingly the battery lasted another few years
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