Auto 2.1 Bosch Starter Motor Solenoid Test

[maxstu]

Decided to dig out a "failed" starter motor for auto 2.1. Tore it apart, cleaned out and added new carbon brushes. Assembled and bench tested. Ran fine for five seconds. Tried another start and nothing apart from sparks each time l hit the jumper wire live side to solenioid contact. No clicking. Nothing. Good earth...tested another starter to check all battery leads working.
Is there another test l can do with solenoid off starter?
If duff where can l source new solenoid reference 134376. Not prepared to take solenoid off running starter in case that one goes under too.

[maxstu]

Right. I did a continuity test following this video clip below. All good. But the solenoid has failed when trying to power up. No clicky click. Nothing. Nada. Just sparks.
So l need a new solenoid for Bosch starter 001212402?

https://www.bing.com/videos/search?q=ho ... AP&PC=SMSM" onclick="window.open(this.href);return false;

[RogerT]

This rang a bell for me

https://forum.club8090.co.uk/viewtopic. ... 9&t=158142" onclick="window.open(this.href);return false;

I mistakenly bought two new solenoids thinking they were all fubarred, but it was just me being an eejit. I still don’t understand, but you might.

Good luck

[maxstu]

Thanks Roger,
Good info. Will read through tomorrow and check.
I do have a working spare starter l fixed earlier this week. But AUTO versions are proverbial hens teeth to find. I could swap solenoids, but dont want to chance losing a good work spare.
Regards
Stuart

[maxstu]

Now more confused! Solenoid is working. I tested ohms and continuity and both met the grade according to the video clip attached in earlier posting.
I added 12 volt live to ignition terminal. Then placing earth to body should throw solenoid. It didnt. But if l touch smaller post it fires....only in this place and nowhere else.
Going back to my other starter. Live to ignition and touch earth to body fires solenoid???
Whats up?
Regards
Stuart

[937carrera]

I'm a bit confused by the testing you are doing, but some ideas:

I assume you are testing off the van, with a battery and jump leads (+ve onto the main post, -ve to the body, jumper wire from battery to solenoid connection)
You have tested the solenoid on its own and that is throwing correctly

Have you checked the internal contacts in the solenoid for the switched current (don't think that's your problem)

Have you thought about a mechanical problem inside the starter. There's a bit of a health warning on testing WBX starters out of the van, have a read here as well https://forum.club8090.co.uk/viewtopic. ... 9&t=138768 I think the issue is the motor shaft can "wobble" and the windings can touch the magnets and be damaged. A physical jam can give the symptoms of sparks and all that electrical energy will be converted to heat.

Have you pulled the motor apart to inspect / clean the commutator ?

Is the main +ve voltage wire in good condition (the one people think is an earth, that turns to dust)

Health warning given, can you check the motor operation without solenoid ?

Bench test is probably best done in a spare gearbox bellhousing, after that a vice, but in practice most of the time it's done on the floor with a foot on the starter to stop it moving, at least by me..

[maxstu]

Hello David,
And thanks for your comprehensive reply.
Briefly some pointers l found on internet last night have helped me..

Starter in rip down mode..
I was checking if soleniod had failed. It had not. I was testing whether it still throws to pull and hold. This l did wrongly, and, whether right or wrong, lm still not 100 percent sure, the solenoid needs earthing to main starter body to work correctly in two phases. Throw and hold.
I now believe the cable between solenoid and starter is the fault. It is in poor condition and perhaps not working as it should. On it later today. Will replace cable and retest
Auto's dont suffer wobble effect manual starter alledgedly do.
Regards
Stuart

[937carrera]

Just think of the solenoid as a relay, just a big one.

Small switching current closes contacts to allow big current to flow

The solenoid just needs to remain engaged

[maxstu]

Just think of the solenoid as a relay, just a big one.

Small switching current closes contacts to allow big current to flow

The solenoid just needs to remain engaged

Just saw a youtube clip showing a s/motor with a defunct solenoid. The poster added a remote solenoid and it worked the starter.
Its very funny too. I might buy a solenoid and give it a go.


https://www.bing.com/videos/search?q=ta ... RE&PC=SMSM" onclick="window.open(this.href);return false;

[937carrera]

I thought you had concluded the solenoid was OK ?

Have you stripped it down and inspected the contacts. You could always engage the solenoid and test for voltage on the terminal that provides current to the starter, but the problem is while the voltage may be there can the contacts (and most importantly the cable) carry sufficient current.

[Cobra88]

The auto starters dont need a pilot bearing like a manual

[maxstu]

Not sure l can get to internals without cutting metal body. Its molded. Its not an original Bosch solenoid either.
It works when removed from starter body. But only by giving power to the long terminal and earth to short terminal. All testings lve viewed shows adding earth to any part of solenoid body will work. This one only throws with earth wire on short post. Then back on starter adding power it just sparks.
The purchase of a remote solenoid was just out of interest

[maxstu]

The auto starters dont need a pilot bearing like a manual

Thanks Rick,
What about the two bearings, one at either end inside starter? What part do they play? End cap one is in good condition. The larger one at the teeth end looks a bit worn and l can spin it with my finger!

[937carrera]

Not sure l can get to internals without cutting metal body. Its molded. Its not an original Bosch solenoid either.

I was expecting a couple of screws on the end plate would give access, the casings can be either solid or "jigsaw" made in two sections

It works when removed from starter body. But only by giving power to the long terminal and earth to short terminal. All testings lve viewed shows adding earth to any part of solenoid body will work. This one only throws with earth wire on short post.

Both the connections on that end of the solenoid are for +ve. The big one for high current, the small spade (or small post in your case ?) for the solenoid trigger. I would expect that the solenoid would also operate through providing the earth.

My only doubt here is a post from Bigherb in the linked thread where he said the earth route is provided through the brushes, as I cannot ever recall a post by him giving poor advice. If that is the actual situation then the earth route is provided from the +ve cable from the starter then goes to the motor. Have you tried that ?

I can't figure out how the solenoid is working in the way you have described either........

The purchase of a remote solenoid was just out of interest

That will be a good test, if it works on the starter, then you know your current solenoid is duff.

[maxstu]

Good reading and thanks. Yes lve read brushes act as earth. As does small end cap held by two screws.
Also all outer body connections must be free of corrosion too. In this case, front part, centre case and end case with small cap.
Lastly the wire from solenoid to starter should be isolated by a rubber grommet in the casing? The one on this starter is a bit manky.