Starter motor

Come here to ask for technical help and advice
Post Reply
User avatar
packers1712
Posts: 196
Joined: 7th October 2010 - 8:58am
Location: Bedfordshire (nr Luton)

Starter motor

Post by packers1712 » 3rd July 2017 - 12:16pm

Hi, my '71 type 3 FI has developed a non starting issue when its hot, in that the starter does nothing until its given a "light tap" after which it will work again, is there anything in particular I need to be paying attention to before i go down the route of replacing the starter? Somebody mentioned to me that the spigot bearing that the starter pinion rests in is sometimes an issue - would this cause my symptom?
Thanks in advance, Doug.

User avatar
broady_6
Posts: 2904
Joined: 13th January 2009 - 8:55pm

Re: Starter motor

Post by broady_6 » 3rd July 2017 - 12:52pm

Yes it certainly could. You can change it insitu with a tap. I think is M12 but i cant remember off the top of my head and cant check till later in the week.

its worth a shot as its a couple of quid vs £70 or so.

Need any pointers just ask and ill be happy to help
The sultan of swing

User avatar
Editor
Posts: 5515
Joined: 10th October 2004 - 8:52pm
Location: Pensford, Bristol
Contact:

Re: Starter motor

Post by Editor » 3rd July 2017 - 12:55pm

Hi Doug,
This is a well-known 'feature' with a number of solutions. I used to find re-starting immediately after shutting down following a run would then allow a normal start when next used worked for a while. It seems the brushes can 'hang up' somehow, and not make proper contact with the armature, maybe expansion with the heat soak of a motorway journey.
There may be a solenoid factor playing a part, or it could be the bush in the bell-housing, or simply a need for the pinion shaft to be cleaned and lightly lubricated. There's details on how to dismantle the starter and clean things at http://home.clara.net/hallvw/starter.htm . You may get away for a while just by cleaning the pinion shaft - depends on how many times you want to try to sort it out!

I eventually fitted a starter relay in the solenoid wire that runs under the mat/carpet past the battery. There's a connector under the seat which is a handy place to get into the loom, and you're next to the battery for the power feed. Using the relay also saves wear on the starter terminals in the ignition/starter switch, which is a bonus for '71 as it's a hard switch to find if it fails. It must be 15 years since I fitted that relay, and the original starter on my '71 still works after 45 years and almost 100,000 miles (touch wood!). I don't much like replacing things with modern inferior stuff!
Dave.

User avatar
packers1712
Posts: 196
Joined: 7th October 2010 - 8:58am
Location: Bedfordshire (nr Luton)

Re: Starter motor

Post by packers1712 » 3rd July 2017 - 1:13pm

Thanks guys I'll start there then and let you both know how i get on!

User avatar
packers1712
Posts: 196
Joined: 7th October 2010 - 8:58am
Location: Bedfordshire (nr Luton)

Re: Starter motor

Post by packers1712 » 4th July 2017 - 9:19am

Quick update on the starter fault, the bush in the bell housing looks good so i tested the starter on the bench and it is very lazy so I'm thinking that maybe its had its day, it does look like the original one, so the next question is where would buy a new one from ?
The ones from Heritage don't have great reviews!

Thanks again Doug.

User avatar
937carrera
Posts: 1190
Joined: 7th June 2013 - 11:54pm
Location: North Yorkshire

Re: Starter motor

Post by 937carrera » 4th July 2017 - 3:05pm

I had a similar issue on my T25 recently.

Can you dismantle the motor to remove the carbon brushes and get to the armature. If you look closely you will probably find carbon build up between the segments on the armature. Clean these out carefully (without causing damage), reassemble and I think you'll find that the starter is back to health - unless the brushes are worn out, in which case replace those.
David
1974 412LS Variant
1973 412LE 4 door Fastback / Saloon

User avatar
Editor
Posts: 5515
Joined: 10th October 2004 - 8:52pm
Location: Pensford, Bristol
Contact:

Re: Starter motor

Post by Editor » 5th July 2017 - 1:44am

You only get the full current when the solenoid contacts close. This happens when the pinion engages with the flywheel starter ring. It's a pre-engaged starter, and initially the current inches it round and moves the pinion outwards. The other thing to note is that with the shaft not in the bush, it's not supported properly.
There's lots of things that can make things sluggish, and you wouldn't be the first to replace a starter motor then find the earthing braid in a poor state.

I read that starter segments aren't undercut - that's only done on dynamos, so give the armature a decent clean. I don't recollect if the brushes are carbon or copper on the starter, but either way you don't want the brush dust on there. It was for a 6V Ford 'Pop' engine in an old aircraft tug, but the same arguments hold good for VWs. https://www.fordbarn.com/forum/showthread.php?t=122717
Dave.

User avatar
packers1712
Posts: 196
Joined: 7th October 2010 - 8:58am
Location: Bedfordshire (nr Luton)

Re: Starter motor

Post by packers1712 » 5th July 2017 - 6:06am

Thanks guys, I was already half way through a strip, clean and reassemble when your message came through 937Carrera and it was filthy. I refitted it last night and it works fine the proof in the pudding will be when I try to do a hot restart- fingers crossed.
Thanks again everyone for your help, Doug.

User avatar
Editor
Posts: 5515
Joined: 10th October 2004 - 8:52pm
Location: Pensford, Bristol
Contact:

Re: Starter motor

Post by Editor » 5th July 2017 - 5:53pm

Well you're over the worst anyway. Mine went quite a while after a clean before it began playing up again, which was when I fitted the relay, since when the problem hasn't repeated.
Dave.

Post Reply