Starter motor won’t disengage and keeps turning - Page 2

P1800 ES · Nov 22nd, 2020, 19:42

Quote:

Originally Posted by HRA

A couple of thoughts for what they are worth:

There's a thick (braided?) copper cable that goes from the solenoid to the field-coil of the starter motor. If that were in accidental contact with the trigger wire to the solenoid then once you'd triggered the solenoid the trigger wire would stay live and the starter would keep on turning.

The solenoid activates a plunger. The push end of the plunger makes the electrical contact for the starter motor. The pull end pulls a lever that pushes the pinion forward to engage. If there's too much friction in the mechanism the plunger may not slide back to the "off" position. The motor works on the bench when not under load, so maybe the extra friction of being under load is stopping the mechanism sliding back? Maybe some cleaning/lubrication around the bit of the mechanism that slides the pinion forward? Perhaps around the plunger too? The Haynes manual shows the lubrication points.

Lastly, when I fitted a later starter motor to my Amazon I initially couldn't get it to start at all. I found that the later solenoid had two similar-looking spade terminals and I'd connected my trigger wire to the wrong one. It might just be worth checking that your solenoid doesn't have an extra terminal that does strange things if connected in error.

Thanks. The braided link from starter to solenoid isn’t in contact with anything. I checked that today. All I can think is that there is extra friction when it’s engaged preventing the pinion from pinging back on its own, or there’s some kind of interference within the starter mechanism preventing it disengaging.

The new solenoid does indeed have two terminals. One is the trigger and the other becomes positive when the starter cranks. That must be for a later car that needs this functionality.

I’m hoping it’s just a problem with the starter unit and not within the bell housing as I’m ordering a replacement unit and feel hopeful that’ll fix it. I’ll be sure to update this as I go. Might be a while as it’s difficult to find time to get to the car and work on it currently.

142 Guy · Nov 23rd, 2020, 01:50

Quote:

Originally Posted by P1800 ES

The new solenoid does indeed have two terminals. One is the trigger and the other becomes positive when the starter cranks. That must be for a later car that needs this functionality.

On K jet and the later D jet equipped cars I think that 'extra' terminal was used to power up the cold start valve to apply extra fuel for starting.

P1800 ES · Nov 29th, 2020, 08:17

Just thought I'd update this as I have now resolved the problem. I fitted a new starter motor unit yesterday and it works fine. Went for a borg and beck unit with m12/100mm/1.75 pitch bolts.

Spins up and performs fantastic. I also started and drove the car for the first time in 26 years. I'll post an update of that on the thread I have for the car.

142 Guy · Nov 29th, 2020, 22:48

Good that it is fixed. By any chance did you ever figure out what the problem was with the original starter?

thx569 · Nov 30th, 2020, 00:10

Two things come to mind. The starter draws watts of power. Amps X volts = watts (power). Low voltage means higher amps to get the wanted wattage.

Low battery will cause excess amps to flow causing the plunger contact disc to overheat and stick (as in weld). This or just a bad solenoid.

If you have disassembled the starter, you might have the fork in backwards causing the bendix drive to push out too far hitting the drive end housing and causing it the jam up (stick in place while spinning thus holding the contact disc in closed circuit). Or maybe you have the fork behind the bendix and not in its intended slot Or groove. There should be about 1/16 or so clearance between the bendix and the end housing when engaged.

Or it could simply be the wrong solenoid. Usually but not always, the issue is in the starter assembly.

P1800 ES · Nov 30th, 2020, 10:17

I haven't yet investigated the fault with old starter motor. On the bench the new solenoid had a reassuring thump, so I don't think it was that. It's all still a bit of a mystery.

All i know is the new starter motor works just fine. I'll keep hold of the old starter and if I find time I'll investigate further.

Nov 30th, 2020, 00:10	#15
thx569 Member Last Online: Sep 6th, 2023 19:43 Join Date: Dec 2012 Location: Winnipeg, Manitoba, Canada	Two things come to mind. The starter draws watts of power. Amps X volts = watts (power). Low voltage means higher amps to get the wanted wattage. Low battery will cause excess amps to flow causing the plunger contact disc to overheat and stick (as in weld). This or just a bad solenoid. If you have disassembled the starter, you might have the fork in backwards causing the bendix drive to push out too far hitting the drive end housing and causing it the jam up (stick in place while spinning thus holding the contact disc in closed circuit). Or maybe you have the fork behind the bendix and not in its intended slot Or groove. There should be about 1/16 or so clearance between the bendix and the end housing when engaged. Or it could simply be the wrong solenoid. Usually but not always, the issue is in the starter assembly. __________________ Licensed automotive mechanic - red seal Licensed heavy duty mechanic - red seal Vocational instructor - ret Death is nature's way of making it harder to get up in the morning.

Nov 29th, 2020, 08:17	#13
P1800 ES Junior Member Last Online: Mar 17th, 2023 06:04 Join Date: Sep 2020 Location: St Albans	Just thought I'd update this as I have now resolved the problem. I fitted a new starter motor unit yesterday and it works fine. Went for a borg and beck unit with m12/100mm/1.75 pitch bolts. Spins up and performs fantastic. I also started and drove the car for the first time in 26 years. I'll post an update of that on the thread I have for the car.

Nov 29th, 2020, 22:48	#14
142 Guy Master Member Last Online: Yesterday 15:52 Join Date: Jul 2020 Location: Saskatchewan, Canada	Good that it is fixed. By any chance did you ever figure out what the problem was with the original starter?

Nov 30th, 2020, 10:17	#16
P1800 ES Junior Member Last Online: Mar 17th, 2023 06:04 Join Date: Sep 2020 Location: St Albans	I haven't yet investigated the fault with old starter motor. On the bench the new solenoid had a reassuring thump, so I don't think it was that. It's all still a bit of a mystery. All i know is the new starter motor works just fine. I'll keep hold of the old starter and if I find time I'll investigate further.

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