S2 pre engaged starter solonoid

[mgcjag]

Hi All....as per the title I have a starter where the solonoid isn't operating....wireing and relays all good and power right up to the solonoid....I suspect the contacts inside but service manual says its sealed/non serviceable ..havent removed starter yet....anyone managed to open the solonoid and get to the insides...Cheers ....Steve

[mgcjag]

OK....in typing the previous post I realise the solonoid isn't operating....power right up to the screw terminal...so probably the winding.....Will get the starter on tbe bench.
Steve

[tim wood]

Hi Steve,
Just buy my one in the “for sale” section ! !

Tim

[mgcjag]

Hi Tim. I noticed your post..... I might well be in touch... Will get on it tomorrow ...when your working on your own its easy to over look the obvious....I was helping a mate do a tune up..all was going well...then all of a sudden it wouldnt turn over.....solonoid didn't operate....Will let you know..... cheers..Steve

[mgcjag]

OK I'm a bit stumped....earths are all good..all the wireing checked out to the starter/solonoid...try to start relay operates and 12v in to solonoid...but it dosnt operate.....so disconnect the 12v lead at the solonoid and jump wire it to the battery and it operates and starter spins......... ... any thoughts....iv walked away from it for a while...Steve

[mgcjag]

OK a cup of tea works wonders...helping a mate and working outside in the cold dosnt help the thinking...turns out to be an intermittent starter solonoid issue...I tried the direct jumper lead again and it wouldnt operate.....a few more tries and its hit and mis...so starter needs to come out....Steve

[Bob.]

Hi Steve,
If you do decide to dismantle the solenoid this may help if the solenoid is similar. It's years since I last did it but the end cover can be wriggled off the winding wires eventually by keeping the solder molten. (Image is of a 19S solenoid on an M45G starter)



I came across this link to a 1973 Lucas document recently, it covers a number of different solenoids as well as a lot of detail on their pre engaged starters of the period. https://www.lrsoc.com/forum/forum_files ... al%20C.pdf

Hope this helps,
Bob

[mgcjag]

Hi Bob...thanks for the reply..hope your well and finished your S3. Great info...Will definitely try to unsolder the solonoid...I do like to find out exactly what the fault is
...I'm thinking possibly a dry solder joint... Steve

[Tommd]

Remember, before you try to take the solenoid apart, an “intermittent solenoid” is often worn or sticking starter motor brushes.
Tom

[mgcjag]

How does the motor brushes affect the solonoid operating?.... Steve

[Tommd]

Steve, the starter solenoid consists of two coils, a pull in coil and a hold in coil. The pull in coil is "grounded" through the starter motor, the path including the motor armature and brushes. The hold in coil is grounded directly to ground. When the starter solenoid is first engaged, both coils are energized and the plunger pulls in. But as soon as the plunger closes the large solenoid contacts, that puts 12v on the previously "grounded" end on the pull in coil, thus de-energizing the pull in coil, leaving the hold in coil to keep it engaged. The pull in coil draws a lot of current which is no longer needed and is now available for the starter motor.
Since this pull in coil grounds through the starter motor, if the brushes do not contact the armature (due to worn out or stuck in the holder) the pull in coil will not pull in to engage the solenoid. I am sure you have heard the suggestion to hit the starter motor with a block of wood if the solenoid is "stuck?" Usually what is happening is the pull in coil is not energizing. Hitting the starter jiggles the brushes down onto the armature and now it will pull in.
See attached diagram.
Obviously, this may not be your particular problem. The solenoid contact disks may be burnt, or of course you may have a bad connection on the solenoid. Just some suggestions.
Tom

[mgcjag]

Hi Tom.. Thanks for posting I didn't realise that the solonoid operated initially through the brushes...I though that as the solonoid operated interal contacts then activated the motor via the brushes....hence the old school bang the starter if you can hear the solonoid operate but the starter dosnt spin....maybee this was with the non preengaged unit where you had a seperate solonoid..anyway iv tried banging it but no luck so needs to come out.....cheers..
Steve

[mgcjag]

Just an update......replacement starter fitted.....all working....I havent delved into the faulty one....mate has sent it off for rebuild....Steve

[mgcjag]

Just for more info a post just on JagLovers re stripping down a solonoid https://forums.jag-lovers.com/t/solenoid-rebuild/440767