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24v starter solenoid

What do you mean by a standard starter solenoid? I would hope you already have a 24v solenoid fitted, if not & it's a 12v one it will draw twice it's rated current & burn out the winding.
 
Hi a 12v solenoid will work the same on a 24v system that is until it gets hot and burns out the it wont start on the key at all , when you say dodgy starter and if its intermittent it ether a flat battery a starter that's on its way out or a bad earth connection to the battery. The solenoid normally works ( you can hear it click when you turn the key) until the contacts or the coil windings burn out the nothing.
if its the starter i have 24v starter on the for sale if that helps.
Mike
 
Ive been using a standard 12v....That will explain the hard starting and now no starting at all (turn key and just hear a click)

(the origional ones terminals were rusted through, and when asking a certain land rover specialist they said that the 12v was the only one available...)

Now i know better, thanks guys...one 24v solenoid on order
 
May be a little misunderstanding in my explanation .

1st the solenoid works by an electromagnet powered by 12v or 24v low current

2nd the contacts that close the circuit between battery and starter.

the Lowe current magnet closes the contacts allowing high current to flow from to the battery to the starter .

so when the Manet is powered it throws the contacts connecting power to the starter.

This is the clicking sound you can hear if the electromagnet had burnt out you will hear nothing .
But if the electromagnet coil is working and you get a clicking sound
and the contacts are burnt out no current will pass to the starter

so no click 100% duff
click sound 50/50 duff
click sound and no current at the starter 100% duff solenoid
click sound and current at starter 100% duff starter

Mike
 
Thanks for the explanation...makes sense :)

Ive ordered the 24v solenoid anyway, if i put everything right it cant fail :rolleyes:
 
Have fun playing and the satisfaction of sorting it , parts are cheep compared to modern vehicles.
old
An old landrover is just big boys Mecarno

Mike
 
Thanks for all your suggestions! Ive followed them and its time for an update

I changed the solenoid to a 24v one and still no joy, so measured the V across the starter...nothing. Measured it across the solenoid....nothing. which lead me to the switch

Looked at the ignition switch, and found nothing across the switch, bingo switch is knackered

The question is now, where do i find a 24v ignition switch??
 
As fare as i know the only variant of ignition switch are petrol and the more expensive diesel . Diesel having a cold start position.
Mike
 
Went to Morleys in Derby this morning and got a new standard petrol one (branded as BM ) fitted and it turns over fine now

doesnt start though...no spark from plug, and no spark from coil center lead to earth.

getting 24v from the filter box to the coil so i assume the coil has gone.

reading past posts i know that when the points close i get 10v to the coil, but does this mean i need a 10v coil or can i replace with a standard 12v?
 
Went to Morleys in Derby this morning and got a new standard petrol one (branded as BM ) fitted and it turns over fine now

doesnt start though...no spark from plug, and no spark from coil center lead to earth.

getting 24v from the filter box to the coil so i assume the coil has gone.

reading past posts i know that when the points close i get 10v to the coil, but does this mean i need a 10v coil or can i replace with a standard 12v? (it has replacement ducelier dizzy and leads)
 
Well you could fit a 12v coil but that means a 16% drop in the input to the 12v coil & will give a 16% reduction in HT output.

Now you could reduce the effect of the reistances in the filter box to allow 12v output. I think the smaller resistance is 0.75 ohms if you by passed that, given that the coil is drawing 3.1 amps originally, would now increase the voltage to the coil as 12.3V.

But assuming you overcame that you run into another problem. The screened sheath over the HT cable acts like a capacitor & some of the HT energy is lost because it has to charge up this capacitance. To try to overcome this 24v ignition systems were designed to deliberately introduce pure resistance into the circuit to reduce the effect of inductance of the coil. So by increasing the ratio of the impedance of the coil (vector sum of reactance & resistance) to the resistance (with no reactance) then you degrade the efficiency of the HT available.

It would be better to do more comprehensive tests on your 10v coil before you chuck it out. If you use a multimeter to test the windings you can even give yourself a small shock on the primary if you touch the terminals.

Just without the coil check that the electrical circuit of the points is ok in that it completes & opens the circuit as the points close & open. Then with the coil in circuit. Measure the voltage at the points to earth which will be 24v (not 10v) & 24v at the coil when open or zero with the points closed (& 10 v at coil)
 
Hi Clive your talking way to technical for my dense brain :newbrain:

just to make sure im getting this ok...

from the filter box im getting 24v (this is the lead disconnected from the coil). When connected, (the + side of the coil) im getting 2.8v (this is with the points open or closed)

opening the points manually i can see a tiny weak spark.

So i now need to measure the voltage from the points to earth (is this from the actual contacts to earth?) and i need to try this with the coil attached and then also removed?
 
from the filter box im getting 24v (this is the lead disconnected from the coil). Good

When connected, (the + side of the coil) im getting 2.8v (this is with the points open or closed) With the points open you should still get 24v, with the points closed it should be 10v. If you are getting 2.8v with the points close, the whole circuit is drawing a dramatically high current rather than just 3amps, which gives a bigger voltage drop. So there is either a fault in coil or the filter box resistors are shorting out. Take the lid off the filter box & check no bits of wire, bolts etc are touching the case. Or one of the filter condensers is breaking down. Put an ammeter in series with the 24v supply to the filter box with it disconnected from the coil it should read zero. If it reads any current ther is a fault in the filter box. With the -ve lead from coil short this to the chassis (same effect as closing the points) it should read 3amps. If more there is a fault in the coil or its leads.

opening the points manually i can see a tiny weak spark. this spark is the voltage induced in the primary winding as the magnetic field in the coil collapses its 200-300v normally. The condenser helps reduce this sparking, which reduces pitting on the points & helps cause a more rapid swich off to enhance the rapid collapse of the magnetic field which enhances the voltage induced


So i now need to measure the voltage from the points to earth (is this from the actual contacts to earth?) yes or the lead in from the coil

and i need to try this with the coil attached and then also removed just with it attached once you remove the coil lead to the distributor then you won't measure any voltage to the points. The role of the points are to intermittently switch the -ve side of the coil to earth. When the points close the circuit is made, the iron core in the coil is being "charged up" with magnetism. The coil does its job when the supply is switched off & the magnetism collapses & induces a voltage in the windings. Both the primary (ie input winding) & the secondary winding (ie output) as the secondary winding has many more turns than the primary a much bigger voltage is induced giving you the HT (high tension of 10-20Kv). Whereas the voltage induced in the primary is 200-300v hence spark as point open, that is the 200-300v trying to jump across)
 
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Many Thanks Clive, i went through all your instructions this morning and was getting some good results apart from finding the V at the points...it was always coming up with 0v not the expected 24v...i was moving the engine over so the cams were at there highest point and the lowest...still 0v

then i thought...hang on if its 0v all the time the points cant be opening...so opened them with my finger and bingo 24v...the points were always closed, i adjusted them and HEW fired up first turn!

so lesson learnt...dont assume other bits are wrong check the points first...

One final question though...how did this happen? the screw in the points was tight so it hadnt slipped...it fired up last time (albeit after a few turns)

oh well at least its now running fine

Thanks everyone esp Clive for your patience, rest assured you have taught me all about my ignition now, much appreciated!
 
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