Understanding the starter motor - After AA man fixed it

1. sri_130 Frequent Poster Joined: Apr 2012 Doyncaster Posts: 783

   #1 30th April 2015, 10:27

   Drives to work location and turns off car, attempts to restart and nothing. Not even a click. Battery fine and all instruments work as expected, but no cranking at all. Checked fuses, all fine - crank sensor fine. So I sit and wait for AA man, suspecting the starter.
   
   AA man arrives and said there wasn't anything getting to the 'solenoid' but yet there was a successful live feed to the starter itself. He bridged the wires and she started up - took him all of 10 mins.
   
   I replaced a starter on another saxo last year, but I've forgotten how the wires/it works. I recall there is a larger positive cable and then two smaller ones (obviously one is a negative/earth) but then this third cable must be for the solenoid? so how does the starter/solenoid actually work then?
   
   Picture stolen from internets:
   
   
   
   So, two large-ish and one small (that looks like its been chopped on that pic). Guessing the smaller cylinder part of this contraption is the 'solenoid'?
   
   Haynes shows:
   
   1. Starter has an earth
   2. Positive from the battery (also shares this to Alternator)
   3. Blue wire to ignition
   4. No fuse or Relay for this particular item (forum searching seems this is accurate)
   
   I believe my issue is 3. The fact there is no feed from ignition to starter and thus the AA man just bridged that with the positive?
   
   What does the solenoid do? and is my understanding, anywhere near accurate?
2. henry2014 L-plater Joined: Nov 2013 Tyne and Wear Posts: 51 Saxo vtr

   #2 30th April 2015, 12:19

   Hi my car turns over, but do u know when the car is started and you turn the key too far it makes that noise.well sometimes my car makes that noise when I go to start it,Ido u think its my starter motor?
3. sri_130 Frequent Poster Joined: Apr 2012 Doyncaster Posts: 783

   #3 30th April 2015, 14:43

   Quote:

   Originally Posted by henry2014 Hi my car turns over, but do u know when the car is started and you turn the key too far it makes that noise.well sometimes my car makes that noise when I go to start it,Ido u think its my starter motor?

   sounds like it's sticking. countdown to a replacement.
4. user_35090 Established Member Joined: Jun 2009 west mids (dudley) Posts: 1201 cammed 106 flatty

   #4 30th April 2015, 23:41

   The solenoid forces the small pinion gear out of the casing, so it contacts the flywheel, it also engages a plunger mechanism internally which creates a small circuit causing the main motor to spin up. And yes, the small cylinder is the solenoid.
   
   Usually a faulty solenoid will spin the motor, but wont force the small gear out resulting in a no start, yet you would hear the starter motor spinning.
   
   Im 90% sure that the big wire on the startermotor is connected directly to the positive on the battery, it could be the negative though, The small thin wire will be connected to your ignition barrel, which when turned, would complete the circuit making the motor spin up. Hence why aa man bridged the two together to get it to start the car.
   
   The 3rd wire that goes from solenoid to motor, the short one, will carry the current from the battery, to the main motor, after the solenoid plunger has engaged and completed its circuit.
   
   You can take a wire from each of those, and create a push button start of sorts, you would still need the key of course but it might be easier to fit one of those than to sort the ignition wire/barrel or whatever it is causing your issue.

   1 user thanked this post: user_39461
5. user_35090 Established Member Joined: Jun 2009 west mids (dudley) Posts: 1201 cammed 106 flatty

   #5 30th April 2015, 23:45

   Also this is a very good video explaining how it works.
   
   https://www.youtube.com/watch?v=8WD5Q_PF3pM
6. holdawayt Saxperience Post Whore Joined: Jan 2010 Stourbridge Posts: 7338 Nissan 200sx S14a

   #6 1st May 2015, 08:30

   Quote:

   Originally Posted by henry2014 Hi my car turns over, but do u know when the car is started and you turn the key too far it makes that noise.well sometimes my car makes that noise when I go to start it,Ido u think its my starter motor?

   You have a flat spot on your flywheel. That's why it's only sometimes, it'll be when the flat spot lands on the starter motor gear. When you spin the starter it doesn't grip properly straight away causing the noise. Stick it in 2nd gear and rock it back and forth a few times. It'll be fine then.
   
   Next time the clutch is done get the flywheel replaced too.
7. sri_130 Frequent Poster Joined: Apr 2012 Doyncaster Posts: 783

   #7 1st May 2015, 08:31

   Nice one! cheers
8. Gandi699 Saxperience Post Whore Joined: Apr 2011 Posts: 9100 Amazon green VTR 16v, Inferno RS clio 182

   #8 1st May 2015, 09:50

   @henry2014
   
   I had to change my flywheel for this very reason a few weeks back, due my own stupid fault mind you not tightening everything up as much as it should be so the starter ate the teeth on the flywheel. The car would start but it got worse quickly, starters just spinning then graucnhing so killing them by destroying the magnets inside and then the teeth on the ring gear just getting worn down. Even just a little bit off the teeth of the flywheel ring gear is enough to stop the starter engaging