Starter motor M45G with solenoid of 3M100?

#1
Hi all,

fixing the earth of the solenoid (see other "car doesn't start" topic) wasn't a lasting solution: my car stopped starting again.
I measured (bought a mmeter!) continuity between S and M that shouldn't be there (thanks startersolenoid.net) so removed my startermotor.

I then saw something strange (or maybe not, that's why i post this): the motor looks like a M45G type (also stamped in the housing), but the solenoid one from a 3M100?
See image:

_1260040_kl.jpg

It worked, the car used to start with this combination, but: is this common?
I'm asking because if i need to replace the startermotor i need to know what to order...

Thanks all,

best regards,

marco

P6 3500 1971
 

SydneyRoverP6B

Well-Known Member
Staff member
#2
Hi Marco,

I doubt you will find a replacement starter motor, at least not a genuine item. You might find one for exchange, but my advise would be to have your one overhauled by an old school auto electrician. The hard part sadly will likely be finding someone that knows how to fault find, and then has the know-how to fix the problem.

Having a mix match between solenoid and starter is not in itself an issue. It may have been assembled that way when, or it may have been overhauled at some point in the past and one part changed.

Ron.
 
#3
Hi Ron,

thanks for your reassuring answer with regard to the found mix!

A starter motor for exchange i can only get via UK, i live in Belgium...
There are a few electricians relatively nearby who say they can revise the starter and solenoid, but they looked for a replacement (new) first.
Made me a bit sceptical. I'll look on.

best regards,

marco.
 
#5
Thanks!
I'll contact them to check if they would want to repair/rebuild in stead of exchange as well.
I contacted a few firms in BE, but none that i really trust with this, and they charge from 150 euro to unknown...

best regards, marco.
 
#6
You're welcome.
They may indeed have one on the shelf. I seem to recall he mentioned to me that a few of the more common units were but he rebuilt mine as no overhauled ones were available at that time which was earlier this year.
 
#9
Today i had time at last to put the revised startermotor back.
Unfortunately it sometimes turns over the engine and starts the car, but more often makes a screeching noise and then the whirring of the rotating starter motor. :(
Could this mean that the bendix doesn't get out far enough or long enough to engage the engine? Is this fixable or should i look out for another starter motor? Do M45G and 3M100 both fit a 1971 3500?

Thanks!
 

SydneyRoverP6B

Well-Known Member
Staff member
#10
Today i had time at last to put the revised startermotor back.
Unfortunately it sometimes turns over the engine and starts the car, but more often makes a screeching noise and then the whirring of the rotating starter motor. :(
Could this mean that the bendix doesn't get out far enough or long enough to engage the engine? Is this fixable or should i look out for another starter motor? Do M45G and 3M100 both fit a 1971 3500?

Thanks!
Hi Marco,
Gee that doesn't sound encouraging. Is the starter motor that is doing this an exchange item? What type is it?

Yes, both M45G and 3M100 will fit your engine.

Ron.
 

jp928

Well-Known Member
#11
Last I understood, a pre-engaged type starter doesnt have a 'Bendix' , which is a gear that is spun into the flywheel by inertia, due to the starting torque.
Check out this page..shows both types.
How the starting system works
I would remove the starter, and see how it behaves with 12V applied to the solenoid (and simulate the relay working)- clamp it on something as it will have quite a kick !
 

SydneyRoverP6B

Well-Known Member
Staff member
#12
This photo illustrates the Lucas 3M100. Although NOS it did not work owing to poor quality workmanship. It would engage but it had no ability to turn the engine. As such I took it to an old school auto electrician who possessed both the skill and a lathe to repair it. Seeing it operate on his test bench, with the application of 12V, the pinion gear flings out to the full extent of the shaft on which it spins. As JP advised, you will need to use a suitable vice that will not move as there is quite a kick there!

20211228_183514.jpg

Ron.
 
#13
Ron: the startermotor is my own, a M45G that has been rebuilt a month ago. Whén it worked, the pinion never was an issue. Could it be that when not receiving the full 12V that the pinion gear doesn't fling out to the full extent?
JP: you are right, i meant the pinion... Language... I'll take it out again (not the most fun i must say) and have it tested.
 
#15
Yes, fresh back from them... A bit of a bummer when i turned the ignition over. I always hope things work perfectly, immediately! :rolleyes:
I already have e-mailed them what it could possibly be.
I wouldn't suppose the flywheel is a factor (or: this has never been the case before), but will remove the starter soon and have a look (at least at the visible part of the flywheel).
 

SydneyRoverP6B

Well-Known Member
Staff member
#16
Yes, fresh back from them... A bit of a bummer when i turned the ignition over. I always hope things work perfectly, immediately! :rolleyes:
I already have e-mailed them what it could possibly be.
I wouldn't suppose the flywheel is a factor (or: this has never been the case before), but will remove the starter soon and have a look (at least at the visible part of the flywheel).
Given your engine was starting before the problem with the stater motor surfaced, and given now after being returned it still isn't starting, I would suggest that they have not undertaken the work to correct the problem. I am aware that this happens, some auto electricians do not possess the necessary skills or willingness to either fault find or repair the problem. They should accept it back and repair it at no additional cost to you, and if they can't do that, then they should refund your money.

I very much doubt the flywheel is a factor.

Ron.
 

quattro

Administrator
Staff member
#18
Unfortunately it sometimes turns over the engine and starts the car, but more often makes a screeching noise and then the whirring of the rotating starter motor. :(
I had a starter problem with my high torque starter motor, where it had failed to fully engage before spinning, and it chewed up the flywheel.

Personally, I would remove the starter, check the teeth on the flywheel, then check the pinion moves freely in and out, you should be able to move it easily by hand. If there is a single piece of grit in there, it could cause the problem you're getting. Then bench test it and make sure the pinion flies outwards fully, then the motor spins.

Then check the mating faces are clean when putting it back in, and also check all of the electrical connections are clean and tight, not forgetting the 6RA relay on the wing and the earth strap on the engine.
 
#19
Thanks all for your suggestions!
I have been cautious to not too often chew at the flywheel but make sure to check when i remove the startermotor eventually.
The company suggested to check if the pinion flies outward fully, and if not: there should be a screw to adjust the position of the pinion (?). Haven't checked this yet.

Have cleaned everything today, including earth strap on engine and the relay in the wing, but when tried to start again i noticed a weird thing, possibly coincidental:
When turning the key the ignition and oil lights come on, as they should: startermotor turns, engage and engine starts immediately. Second try: same thing, so i was hopeful the cleaning had done the trick. Then: 3rd time: oil light didn't come on (?) and the startermotor didn't engage the flywheel...? 4th time: same again. I didn't try any further as to not damage the flywheel. So possibly the startermotor is fine, but something else is wrong since putting the startermotor back? I really haven't touched anything apart from the thing itself and the local wiring and connections...

Does this sound like something anyone has experienced and knows what it could be, besides electrical trouble somewhere in the dodgy wiring?
 

colnerov

Well-Known Member
#20
Hi, Try checking the ignition switch, it could be losing connectivity between terminals inside. You could try hotwiring the leads to it to take it out of circuit. It could be the starter relay but the fact you lose the oil light suggests the ignition switch.

Colin
 
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