Burnt out starter motor - caused by faulty ignition switch? How to test that!?!?

mrtask

mrtask

Well-Known Member
I was briefly left stranded yesterday when my car wouldn't start again after a brief stop. Not so much as a single audible click from the starter motor. Perplexing!
AA arrived very promptly and diagnosed a burnt out starter. The helpful chap said it was really really hot. He gave me a bump start to get me home, so at least I got the blue beastie back in the garage.
So far I've taken photos for reference of what wire went where, pulled the wires off, and removed the two bolts holding the starter to the block and bellhousing, before quickly running out of enthusiasm for lying on a cold concrete floor without any illumination and hardly any room to wield tools! Battle will resume Monday morning, armed with my newly acquired hammer and short pry bar, and hopefully I'll manage to get the starter motor off to take it for refurbishment. It seems to be stuck in place just from memory!
Thing is, if my ignition switch is at fault, surely that will just do the same thing to the newly rebuilt starter motor!?!
Fellas, would any of you like to patiently explain how I diagnose if the ignition switch is duff? And no, I didn't actually go and get that multimeter yet! Guess I'm gonna need it now though, right!?
 
Perhaps i am missing something, but i would expect the starter body to have engine block temperature, therefore if your stop was indeed brief, one could perhaps describe the engine block and starter body temperature as "really - really hot" anyway.
So before taking the starter out, i would suggest to try the simple things first. Switch and relay. You could even try a direct feed to the starter, if you know what you are doing and being very carefull.
 
What he said ^

If there was no click when you tried starting I’d look at the solenoid (separate if an inertia starter on a SI four cylinder) or the ignition switch.
 
I would just check that your earth lead is tight before pulling the starter out, perhaps even removing it, giving the contact areas a good clean and putting it back and making sure the bolts are tight.

To test your 6RA relay on the inner right hand wing, ( I am assuming your wiring is the same as mine) pull off the W1 wire, should be White/Red and make sure it doesn't touch anything. Then get a known live, like the green on the washer motor, and run wire from that to W1. It should spin the starter.

Was you car originally an Auto?
 
Demetris, the car had been standing for about a half hour, and I hadn't driven far or for long before I stopped, just about far enough to put the choke in. The AA guy, formerly a Porsche UK mechanic, seemed to know his stuff, so I reckon I trust his diagnosis.
The starter is still in place and I could simply tighten the bolts and reinstate the wires, and try Quattro's suggestion how to test the relay. Which earth lead am I checking!?! Doh! The starter has an earth lead if its own?
How do I establish if the ignition switch is at fault?
I had used the cigarette lighter, which takes about 30 seconds to get glowing, shortly before the car then wouldn't start - surely that wouldn't have damaged the ignition switch ???
Sorry to be so dim and thanks for the helpful suggestions and guidance!
 
OK, but it is always a good practice to start with the simplest things.
The starter motor does not have its own earth, it does earth through the engine block, so check the engine earth, or even bridge the engine block with the base unit using a jumper lead.
By following quattro's suggestion, you bypass both the switch and the 6RA relay. If the starter spins with this method, then either the switch or the relay is at fault (you can find out out which of the 2). If it doesn't spin, then there is either a fault of the solenoid, or the motor itself, so you have to remove it as a unit for service or replacement.
 
The earth lead is a braided cable running from the bottom of the N/s of the engine to just under the engine mount.

Earth wire.JPG

If the 6RA clicks when you test it, but the motor doesn't spin, then it's more than likely the starter needs repair. If the 6RA relay doesn't click then suspect the 6RA.

If the 6RA clicks when you test it, and the motor does spin, suspect the ignition switch, but also if your car was an Auto, their would have been a switch on the gearbox between the ignition and the 6RA which would stop it starting if the car was in gear. I have seen these wires just joined together by twisting them with a bit of insulation tape - that could cause an issue.
 
Thanks for the further guidance, Demetris and Quattro. I concur, it is of course best to start with the simple things! If I only had a clearer idea how to proceed! I'm probably a bit too gung-ho.
Anyway, this'll amuse y'all; Turns out I wasn't even up to the supposedly simple task of freeing off and removing only two bolts keeping the starter motor in place. (Shakes head in shame) I had removed the top bolt, but had then loosened off an adjacent but completely unrelated bolt, which I only now realise must be holding the bellhousing in place. Doh!! My excuse is, I couldn't see anything under there! (I know, I need to get myself a good inspection lamp) Good thing a Rovering mate of mine has a functioning brain. He popped by this morning to provide moral support whilst I wailed on the back of the starter with a hammer and various bits of timber. Finally, fed up of my cursing but getting nowhere, he rolled up his own sleeve, reached in a dark recess behind the starter motor, and laughed loudly as he pointed out my error. No amount of bashing on my part would've budged anything, as the overlooked lower bolt was still on tight!
Anyway, he ran me up to Borehamwood to the starter motor repair place, who immediately ascertained that the solenoid was stuck in the engage position. The chap there reckons I'll have it back fully refurbished by Wednesday. I already know it'll take a bit longer to put back in place than wrestling it out!
So, anyway, if I wire the starter up on the floor before I bolt it back in, and it spins, I can then test the 6RA or diagnose a faulty ignition switch, right? My car was once an auto, but I don't remember how that inhibitor switch was bypassed. I'll crawl under there and have a butchers...
 
Thanks to Bradley at Unit Exchange in Borehamwood my starter motor is once again as good as new. I actually thought it was a brand new one, until I saw the 'wallop marks' I had made to it, under the shiny new silver paint! Apparently every constituent part of it had seen an arduous half century of service, so pretty much everything got replaced, but it should now outlast my life expectancy!
Armed with a new lamp I crawled back under the beastie this morning, and it all went back in a damn sight quicker what with being able to actually see what I was doing. .....aaaaaand – it works! Back on the road. :):thumb:
 
sdibbers said:
So back on the move then?
Click to expand...
Well, I was, for a day or two, and then it quit again!
(I double posted my short lived good news on my project thread as well, coz I refer back to that when I can't remember exactly when I sorted a problem or installed a new component.)
I charged the battery overnight, got a 13.6 Volt reading and five full bars on the little battery icon on my slow charger.
No change. No click from the starter solenoid. I cleaned up the engine to chassis earth contacts. Made no difference.
I tried bridging the starter relay to the windscreen washer live, but it didn't turn the starter, nor could I hear the relay click.
I searched my parts stash, located a spare 6RA, tried that, still no start.
Called the AA again, the dude measured the same voltage across the battery poles, at the starter relay and at the starter motor. The guy then tried an external starter battery straight to the starter, but no joy. He said I should take it back out and go back to the place who refurbished it.
Did that this morning, and needless to say when I got there the starter functioned perfectly on the test bench.
Came home, put it back in the car, but there's still nowt going on.
I am ever so perplexed.
Have I now established that neither of my starter relays is any good any more? Or did I just prove the fault is at the ignition switch?
Brain trust, what say you?
 
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