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405 petrol starter motor - Crinkly Dave
I have a high mileage carburettor with a problem when warm/hot that the starter will not operate. It's been like this intermittently since I acquired it 10 years ago.
Basically, the starter will spin the engine over when cold, but if you leave it a few minutes when hot the starter will not operate. Open the bonnet and go for a cup of tea, and it will start immediately. Leave it at work/shops for an hour and there is no problem. Start it as soon as you stop, and no problem. The 405 is famous for high underbonnet temperatures. About 8 years ago I convinced myself it was the starter solenoid sticking when hot, so I fitted a new Lucas one. Problem recurred almost immediately. I have gone problem seeking when it occurred, but of course the thing is intermittent and looking for it (with bonnet open) cures it as you work. I have soldered all the joints in the cable from ignition switch to solenoid, and changed the terminal end to a really tight one, and checked all connections, fuses and spade connections to the power supply.
Problem occurred intermittently, if left for a few minutes after a run.
Yesterday the starter failed (it has done 8 years and 100k) so I whipped it off and put on the original. Instant success. Started it up this morning, and went to local shops only a mile away and back,and parked up. 5 minutes later it wouldn't start. 30 minutes later it started up without a problem.
Ideas, before I get another starter, just in case the solenoid is faulty on this one, really.
405 petrol starter motor - LeePower
Hi

This a really well known problem with the carburettor 405s

There was a modification done by Peugeot to make the cooling fans run without the ignition key for up to 12 minutes if the car had got too hot, after you had parked up & left it to cool the engine bay down.

Ive no idea what the modification was im afraid.
405 petrol starter motor - pienmash
sensor mod,i did read it somewhere
405 petrol starter motor - Crinkly Dave
LeePower, Pienmash
Thanks for the idea. I am pretty sure the 405 has the mods, as the fan kicks in for up to 30 minutes after the engine has been turned off, for several minutes. Bit like an RB211. This, and the high temperatures may be the reason for the 3 yr max battery life.
I think I have the classic case of 2 different faults occurring simultaneously, and misdirection
When it failed after a 2 mile run I blamed the heat. On Sunday it failed after SWMBO had moved it a yard, so it was not hot. I was instructed only the 405 would do for the job in hand, so pushed it off in reverse, intending to push it off after picking kids up from Wales (or keeping it running!)
When I got there the thing wouldn't start, but when I shorted the solenoid to the battery the thing spun immediately.
Back at home I tried it several times. Each time the thing started when shorted out (drawing about 9 amps). When I tried with the key it recorded 12v when not connected to the solenoid, dropping to 7 - 9 v when connected to the solenoid (and not starting). "At last" I thought, it has failed completely and I can find the faulty connection. Probably the ignition switch.
I jumped in it tonight, intending to remove ignition switch and change it for another. I turned the key out of habit,and it kicked in!
Nevertheless I removed the switch and stripped it down, noting wear, but not terrible wear, and a little arcing.
I even managed to put the thing back together again (it was an explosion of copper bits and springs, and it still works. Off to the scrappy tomorrow
405 petrol starter motor - GIM
Quote(out of electrical Manual):

Thermal fuses. This is similar to an electrical fuse but is designed to break the circuit at a specific temperature. These are often found buried under the outer covering of motor windings.

I wonder if this is the fault on your starter motor?
405 petrol starter motor - Crinkly Dave
No, I don't think this is fitted to automotive starters. If it were, why would it work when shorted to a 12 V supply but not via the key.
I suspect the switch or the 2 connections, having soldered any other connection.

if this doesn't work I will fit a new wire from the switch to the solenoid
405 petrol starter motor - Civic8
Dont know the 405.it may be a prob to do with starter commutator.as I recall some cars had brushes mounted on surface of ie rear end commutator.if it had wear on opossite sides it got stuck ie no contact so It wouldnt work.same applies to brushes that contact from side.just a thought so may be wrong.sorry I didnt explain properly.?
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Was mech1
405 petrol starter motor - Crinkly Dave
Yes, I know that modern starters don't have brushes which press on the circumference of the commutator, but on the end face. I suspect that this is the problem with the one which I took off. I will investigate after sorting out the 405, Punto
Doesn't explain the present symptoms with the voltage drop at the solenoid though
405 petrol starter motor - Civic8
Ignition switch will cause that.sorry didnt read your post correctly?
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Was mech1
405 petrol starter motor - Crinkly Dave
News is that I think I have cured it (fingers crossed), leastways it hasn't returned for the last 4 weeks. What I did was to take a cable from the ignition switch direct to the solenoid. I know this is obvious, but had checked all the joints and replaced any not 100%
I had assumed a break or fault in the wiring. When I double checked I had the correct cable by shorting out the ignition switch with my ammeter I recorded about 4 amps several times, spinning over the engine without the ignition on. Suddenly my 10A ammeter overloaded and the engine would not turn over. However operating the ignition switch made it work.
I can understand failure due to a wiring fault, but not a fault which could cause this quantity of overload. A simple short would have failed years ago.

Fingers crossed