Technical Starter Motor

[fistral64]

I have a 1971 Fiat 500 L and recently my starter motor stopped working. I have removed the motor from the car and tested it on the bench with jump leads and a battery, but nothing happened. I replaced the switch but still nothing is happening when tested. I have even tried to jump start it from my car but no luck. Are there any other tests I can do before I have to buy a new stater motor?

 

[the hobbler]

Funnily enough, I am overhauling a 126 starter for a colleague at the moment (got to keep busy). Take the switch off the top and connect your jump-lead directly to the contact---Take the brush cover off and check that both brushes are making contact with the commutator and have not stuck. There are other continuity checks that can be carried out, but I willleave the description of those to the clever people.
When testing the starter, make sure that is securely held in a vice--when it works, you will be surprised as to how much it will 'kick'

 

[fistral64]

I removed the switch and tried to connect my jump lead directly to the contact but nothing. I removed the brushes and gave them a clean before replacing them. They seemed to be moving freely and the springs went back into position. I reassembled and then tried to apply the jump lead to the contact with the negative clamped to the housing, but still nothing.

Anything else I can try?

 

[SpyderJava]

A few weeks ago my starter had seized internally. I had to disassemble and remove the armature. Then clean it and reinstall. Does the internal parts spin freely while you have the starter out?

 

[fistral64]

I have stripped down and cleaned everything with a de-greaser. Everything is moving freely so I have rebuild the starter and unfortunately still nothing when I connect a battery. I fear a new starter is required.

 

[Toshi 975]

Did the motor just stop suddenly or was there a gradual deterioration in performance?
Are you happy that there is enough meat left on the brushes for them to make good contact with the commutator?
If they are too worn the pressure springs bottom out so starter will not work.
Is the commutator fairly clean or is the copper blackened?

 

[fistral64]

Did the motor just stop suddenly or was there a gradual deterioration in performance?
Are you happy that there is enough meat left on the brushes for them to make good contact with the commutator?
If they are too worn the pressure springs bottom out so starter will not work.
Is the commutator fairly clean or is the copper blackened?

The starter motor just stopped working. I tried the headlight test but the lights did not dim which suggested to me the problem was electrical. I took the starter off to test it an nothing. There was a lot of blackened parts but I have cleaned them and put it back together now but still nothing happens when tested.

 

[F123C]

I'll assume you checked the battery state of charge, the cleanliness and security of the battery leads, also the battery earth lead to body and earth lead between engine and body before you removed the starter motor.

Was the battery used to test the starter motor out of the car in a good state of charge?

Do you have a multi-meter or ohm-meter? If you have, you can check out the field coils (8.1-8.3 ohms), also check for shorts/open circuits on the commutator segments. To check for a short in the armature, there should be no continuity between the armature centre shaft and any of the commutator segments. To check for an open circuit in the armature windings, you connect iirc, the ohm/multi-meter leads to directly opposite segments on the commutator, I can't recall the ohms figure but iirc it's only a few ohms?

If you haven't got a workshop manual, there's a free one available in the Downloads section (in the blue band at the top of the page). If you look this one up, see page 114-115 for starter motor checks, the resistance figures for the field windings are given here. Also page 113, last paragraph for info on signs of different types of armature failure.

When I read your 1st post, I thought of a dead spot or lack of continuity in one place on the starter commutator but as you've removed/stripped/re-assembled the starter, it's unlikely the armature went back in exactly the same location that it failed in. However you could try rotating the armature a little and then apply power, just to rule out a dead spot on the commutator as the problem.

Sudden failure of the starter motor is unusual, usually the motor function gradually deteriorates - unless e.g. a connection breaks, but you've had the motor apart, cleaned and examined everything carefully.

I always prefer to rebuild my own starter motors etc. - you never know how good a job (or not) that someone you don't know has done. Cheaper too

Al.

 

[Toshi 975]

I had a problem with a starter last year and it turned out that the internal connection to the field coils had broken off.

 

[fistral64]

I'll assume you checked the battery state of charge, the cleanliness and security of the battery leads, also the battery earth lead to body and earth lead between engine and body before you removed the starter motor.

Was the battery used to test the starter motor out of the car in a good state of charge?

Do you have a multi-meter or ohm-meter? If you have, you can check out the field coils (8.1-8.3 ohms), also check for shorts/open circuits on the commutator segments. To check for a short in the armature, there should be no continuity between the armature centre shaft and any of the commutator segments. To check for an open circuit in the armature windings, you connect iirc, the ohm/multi-meter leads to directly opposite segments on the commutator, I can't recall the ohms figure but iirc it's only a few ohms?

If you haven't got a workshop manual, there's a free one available in the Downloads section (in the blue band at the top of the page). If you look this one up, see page 114-115 for starter motor checks, the resistance figures for the field windings are given here. Also page 113, last paragraph for info on signs of different types of armature failure.

When I read your 1st post, I thought of a dead spot or lack of continuity in one place on the starter commutator but as you've removed/stripped/re-assembled the starter, it's unlikely the armature went back in exactly the same location that it failed in. However you could try rotating the armature a little and then apply power, just to rule out a dead spot on the commutator as the problem.

Sudden failure of the starter motor is unusual, usually the motor function gradually deteriorates - unless e.g. a connection breaks, but you've had the motor apart, cleaned and examined everything carefully.

I always prefer to rebuild my own starter motors etc. - you never know how good a job (or not) that someone you don't know has done. Cheaper too

Al.

I tried a different battery and even tried to jump start it from my car; no luck. I have now bought a multi meter so now I just need to figure out how to use it so I can test the coils. Any advice on using a multi meter would be greatly appreciated.

 

[F123C]

Any multimeter I've seen came with instructions - have you checked the packaging?

Rather than try to explain in words (I can't post pics at the moment) how to use a multimeter, may I suggest you type e.g 'How to use a multimeter' into your search engine box. If you do this, you'll find a multitude of tutorials which will show and explain how to use a multimeter better than I can. I'd suggest avoiding those that mention electronics or home electrics and pick one that mentions cars or e.g. testing switches/components.

With regard to testing out the armature windings and the field coils that I mentioned in my earlier post, you'll need to set the meter to measure 'Ohms', which is a measure of electrical resistance. Measuring resistance is always done with no power flowing in the circuit, so the component being tested needs to be disconnected, the power to conduct the test then comes from a small battery inside the multimeter. On some meters, instead of Ohms, the Greek letter omega is used instead. (and there's no 'omega' symbol on my keyboard :bang: )

You don't have to master all aspects of using your multimeter (it can be a bit overwhelming to a beginner), just concentrate on measuring resistance (Ohms) for the moment, this is all you'll need to check out your starter motor windings.

I'm glad you invested in a multimeter and I'm confident you'll come to view it as a very worthwhile investment over time, you'll probably wonder how you ever managed without one, it really does allow you to 'see' what is happening in an electrical circuit instead of guessing. It just takes a little bit of time to get used to using it.

Al.

 

[fistral64]

Stripped it down and tested the coils with the multimeter and all tested OK. I have cleaned everything, again, replaced the brushes and put it back together and now it is working perfectly.

 

[the hobbler]

Well done---give yourself a 'golden star'

 

[F30Msport]

So I believe my starter just went. The last couple times I started it it seemed sluggish (the starter) , but once it was running things were all good. Now I tried to crank it up and the starter sounded almost like it was getting stuck and then stopped working all together. does This sound like the starter? Have no other issues in the engine compartment. Should I try to take it off and give it a once over?

 

[F30Msport]

Here's what I got once I took the starter apart. I plan on getting new brushes and bushings, but not sure about a new bendix and/or starter field coil. Also the switch is a bit worn- can that rubber piece be replaced?

 

[F30Msport]

@Toshi 975 what do you think?

 

[Toshi 975]

@Toshi 975 what do you think?

It looks far from the worse one I have seen over the last two weeks. Your next job is to give everything a good thorough clean inside and out. It will be a lot easier then to assess the condition but first impressions are not bad but definitely worn brushes. I will measure new ones later.
new bushes are very easy to fit and as far as I can tell those original 500 rubber boots are no longer available. Suppliers are selling 126 ones and labelling them as 500. They don’t quite fit and are very fragile with poor quality rubber. I rescued a couple of originals by thorough cleaning and super glue.

 

[Toshi 975]

New verses worn brush pictures

 

[bugsymike]

Here's what I got once I took the starter apart. I plan on getting new brushes and bushings, but not sure about a new bendix and/or starter field coil. Also the switch is a bit worn- can that rubber piece be replaced?

Field winding in the outer casing look a bit dark, do they have a strong smell as though they have overheated.
If buying s/h electrical tools , drills etc. we always used to have a "sniff", if they smelt pungent it usually meant they were shot.
Having said that, it is always worth trying to repair old parts as unlike stuff nowadays, it was meant to be repaired.
You can test quite a lot just using a cheap multimeter.
If it was just the field windings overheated often the starter would still work but not spin so fast and when under load would take a higher amperage to turn the engine over.
If the brushes have worn very low, the spring that keeps it in contact with the commutator cannot exert enough pressure , this allows sparking and damage to the commutator. I not too bad the copper contact area can be cleaned up with fine wet and dry sandpaper, afterwards the gaps between each copper strip must be gently cleaned out so as not to bridge between, then cleaned with alcohol, refitted with new brushes etc. There used to be a tool for the job, but a skilled lathe operator would have no problem.
Other members have shown the pull start contact and pinion engagement mechanism, it is the part that has to take a sudden high amperage connection which will spark and get hot, especially if pulling the lever is done "half heartedly".
I managed to repair a electrical starter solenoid on a Peugeot 504 diesel where the solenoid magnet side worked fine, but due to mileage (175k) the copper contacts inside had severely burnt, the main in and out copper terminals being substantial I was able to file flat to make a good contact but the copper bar the solenoid bridged them to work was in a bad way, fortunately I was able to unbolt it and turn it over, so a couple of hours saved the cost of trying to obtain a new solenoid which was not readily available at the time and the car was used for many years afterwards

 

[Toshi 975]

I will add more findings and observations on the Starter Motor Rampage thread I started. One interesting little story, a guy on another forum was pleading for a solenoid operated starter for his 650 engine. I told him that I had a factory reconditioned one in my cupboard and quoted him a price which was less than half that of a major UK supplier and no exchange was needed. He backed out at the last minute saying he had found someone to rebuild his original for less. My one sold about two weeks later then after a couple more weeks the original guy was looking for a starter again. His rebuilt unit had failed in days