Starter motor rebuild - refitting brushes

[marlinowner]

Return off starter body - easiest with jump lead.

[Oldiebut goodie]

The braid between the solenoid and motor is the main current carrying cable to the starter motor not an earth! All earthing is done via the body of the starter and solenoid.
Negative/earth to the body of the solenoid. This will actuate the solenoid and you can then check the resistance between the the big ring terminal stud and the braid - you may have to clean up the braid to get good contact. This will tell you if the contacts in the solenoid are fried and making poor contact. Low resistance around 0.2 ohms to 0.5 (Most meters have a starting resistance across the leads of around 0.2 ohms) means that contact is good. Anything going much higher will show poor contact.

[orangebooboobearcrew]

Hello gang,

Just a quick update.

I tested the solenoid as mentioned (starter off the vehicle but solenoid still attached) today.

I got the solid thwack each time I touched the spade, the solenoid triggered and the gear shot out. I did this several times and every time it worked so I do not believe the solenoid is suspect although I did not do the resistance test as wasn't quite sure what to do tbh.

So next I am gonna soak the new bush in engine oil overnight then fit that, along with the slightly refurbed starter, back on the van next weekend and give it a turn over and see where we are at.

I am now thinking poor earth return at battery terminal or battery terminals not tight / tarnished or worse still, tight , partially seized engine...you never know, I may have already fixed the problem without knowing it...

[CovKid]

The solenoid does two jobs. The first part you've verified as working but the second part is when the two nuts on the outside of the solenoid are effectively bridged from within, allowing a heavy flow of current down the braid and energising the starter. The two heavy contacts inside the solenoid can corrode, reducing current flow and weakening the output of the starter. Therefore the solenoid can still be suspect.

Given the price of a new solenoid against a new starter, it may pay you to swap the solenoid out. The alternative would be chancing your arm on a new starter and for the most part thats what tends to happen, mostly through frustration. However, in practice any weakness in the starter's ability to turn is usually:

a) poor earth (less likely but possible)
b) poor connection through starter (solenoid contacts, braid or bushes) - includes broken/frayed main cables to battery
c) Worn oilite bush.

Any weakness in (B) will see power being lost as heat. Something somewhere will get very warm if the starter does actually operate.

As an aside, I've convinced myself in the past that a tight engine has been the cause but a starter generates a LOT of power when in good order and should have no prob turning over the engine. Its also worth noting that replacement starters (depending on where you buy) will have had little work done other than what you can do yourself. New solenoid and brushes tends to be the main and sometimes only changes (plus a good clean and respray) - both of which tend to degrade over several years in no particular order.

[orangebooboobearcrew]

The solenoid does two jobs. The first part you've verified as working but the second part is when the two nuts on the outside of the solenoid are effectively bridged from within, allowing a heavy flow of current down the braid and energising the starter. The two heavy contacts inside the solenoid can corrode, reducing current flow and weakening the output of the starter. Therefore the solenoid can still be suspect.

Given the price of a new solenoid against a new starter, it may pay you to swap the solenoid out. The alternative would be chancing your arm on a new starter and for the most part thats what tends to happen, mostly through frustration. However, in practice any weakness in the starter's ability to turn is usually:

a) poor earth (less likely but possible)
b) poor connection through starter (solenoid contacts, braid or bushes) - includes broken/frayed main cables to battery
c) Worn oilite bush.

Any weakness in (B) will see power being lost as heat. Something somewhere will get very warm if the starter does actually operate.

As an aside, I've convinced myself in the past that a tight engine has been the cause but a starter generates a LOT of power when in good order and should have no prob turning over the engine. Its also worth noting that replacement starters (depending on where you buy) will have had little work done other than what you can do yourself. New solenoid and brushes tends to be the main and sometimes only changes (plus a good clean and respray) - both of which tend to degrade over several years in no particular order.

More great advice! thank you. I think you're right, whilst the starter is off the vehicle and for the cost, I may as well swap out the solenoid as at least it should eliminate that as a cause (assuming a new one isn't dodgy as well!).

I just need to try and find the right one for my starter now - it's a hella I think but will see if it has a part number stamped on it anywhere...

[CovKid]

A photo may be enough to work out correct solenoid. Chances are its a bosch starter. If the replacement solenoid doesn't cure it (and I think it will), at least you've got a spare solenoid. I never trade in a starter I think can be revived (even if apparently dead) as they're so ridiculously expensive and nine times out of ten you can sort the problem fairly easily. Most don't because they don't understand how they work. Mind you' I've traded in really rusty ones.

Double-check that braided wire - they're known to corrode away or even break off from the inside.

[orangebooboobearcrew]

A photo may be enough to work out correct solenoid. Chances are its a bosch starter. If the replacement solenoid doesn't cure it (and I think it will), at least you've got a spare solenoid. I never trade in a starter I think can be revived (even if apparently dead) as they're so ridiculously expensive and nine times out of ten you can sort the problem fairly easily. Most don't because they don't understand how they work. Mind you' I've traded in really rusty ones.

Double-check that braided wire - they're known to corrode away or even break off from the inside.

Ok - solenoid removed this evening. Took all of 1 minute!

Part number stamped on side of starter is vwaudi 091-911-023A. I will try and take a piccy of solenoid tomorrow night and post up...

I have no intention of trading in the starter following inspiration from the numerous posts on here to refurb it - now done. (The braided wire is defo fine).

I think I might as well change the trigger wire as well while I'm at it. Any idea of what gauge it is? I presume I need c.4 metres again like the main power cable?

Looking forward to putting it all back together at the weekend hopefully - fingers crossed it will be resolved...

[Oldiebut goodie]

Check the resistance of the solenoid contacts - you may not need a new one.

[orangebooboobearcrew]

Check the resistance of the solenoid contacts - you may not need a new one.

Yep - agreed, again good advice.

So, just for my simple mind, could you confirm the process for this testing is as follows:-

Put 12v+ battery onto spade on solenoid.
Put 12v negative earth return from solenoid body to battery negative post.
Then solenoid will be actuated.
Once actuated, push plunger back in by hand.
Whilst plunger is pushed back in, measure resistance in ohms across both studs?

In terms of getting a replacement solenoid if one is needed, not seeing a lot of this type around - couple from the USA but about £40-£45 due to the postage and don't want to be paying that much tbh...


Cheers,

Chris F

[Oldiebut goodie]

Measure whilst the solenoid is actuated - this is when the contact is made.
Take a look at this video on this page: http://4nt.wikispaces.com/starter+motor

[orangebooboobearcrew]

Ok - some interesting results on the starter testing

I put the multimeter onto the continuity buzzer setting which also shows ohms then connected the prongs to the 2 studs and held them in place by tightening the nuts up on them.

When I pushed the plunger in by hand (pushed it against the floor right to bottom of stroke) I didn't get the continuity buzzer every time, it was intermittment; very intermittent...! I also got silly high ohm readings.

So I tried taking the return spring out to ease closing the circuit and this was much more consistent. I did this probably 30-40 times and got the buzzer and a sensible ohm reading each time ranging from 0.1 to 3.0 ohms, but overalll, as an average, it was below 1.0 ohm - so that sounds good and in the right range / consistent.

I tried putting the spring back in and repeating the first test but same result as first time. I did notice that the inside of the plunger has some surface rusting. Could this be affecting the circuit and be removed by light sanding?

I then thought I would try the solenoind operation via 12v source so connected 12v+ via lump lead from battery +ve to spade on the solenoid and the other jump lead as an earth return from the stud used for the braided wire back to the battery -ve. The solenoid worked and the plunger withdrew as it should but I left this wired up like this for a little wire then noticed a strong burning smell and noticed the solenoid body was mega hot (but not the cables). Is this normal?

So, overall, I am not sure what to make of these results! Any thoughts greatly appreciated...

Thanks,

Chris

[Oldiebut goodie]

I told you earlier - the braided wire is NOT a negative - it is the main current carrier to the motor!

What was the resistance when the solenoid was actuated by 12v? That is what you were supposed to be measuring. Doing it by hand without the spring doesn't exactly simulate operating it by 12v.

[orangebooboobearcrew]

I told you earlier - the braided wire is NOT a negative - it is the main current carrier to the motor!

What was the resistance when the solenoid was actuated by 12v? That is what you were supposed to be measuring. Doing it by hand without the spring doesn't exactly simulate operating it by 12v.

I didn't use the braided wire as the earth return as the soleniod is not connected to the starter, I used the lower stud only.

If this was wrong and I should have used the solenoid body for earth return, I'm sorry - you have to remember this is all new to me so I am learning as I go, hence my previous requests for step by step idiot proof directions...

I had trouble earthing from the body as nowhere to connect to easily and just touching the wire against the body generate sparks and means I have one less hand to use...

I will have to try again tomorrow evening as can't remember the readings on 12v actuation...

[CovKid]

That would mean you were testing the solenoid contacts with minimal load (no motor) so it will get hot within a short space of time. Such tests should be short-lived. If continuity tests are not consistent as you say, replace the solenoid, put it all back together and all should be well. The burning smell will be the contacts within the solenoid and even more reason to suspect thats the fault. When you get a new one, break the old one apart and you'll see what I mean.

[orangebooboobearcrew]

That would mean you were testing the solenoid contacts with minimal load (no motor) so it will get hot within a short space of time. Such tests should be short-lived. If continuity tests are not consistent as you say, replace the solenoid, put it all back together and all should be well. The burning smell will be the contacts within the solenoid and even more reason to suspect thats the fault. When you get a new one, break the old one apart and you'll see what I mean.

Yes I think I want to replace this now (hopefully I didn't fry it when I was testing it! ).

Problem I've got is trying to find a replacement. The starter motor part is 091-911-023A but I have done loads of searching on Google and e-bay and can't find a replacement solenoid for that other than in the USA which costs loads because of the shipping (£40-£50+!) . These also won't be here anytime soon due to the shipping time.

Corresponding solenoid part numbers appear to be SSBO-754B/0-331-303-055/025-911-287 or SO-B0876 (I think), but I just can't seem to find one anywhere, other than the USA.

Does anyone have any idea where I might get one of these?

Thanks,

Chris