Starter circuit mystery button

[david painter]

Starter motor will draw well over 100 amps. You are not powering starter motor from ignition switch, but the solenoid. Which basically a relay. It would briefly take 20 to 25 amps to power it, once engaged less than 10 amps to keep it powered. This amount of current draw is enough to overload the inhibitor switch circuit causing the fault. Installing a relay is a very good idea as it reduces the current draw in the inhibitor switch circuit to that of the relay energising coil, typically 0.25amp. However the cause of the original fault must be traced as the damage has already been done. Fitting a relay just stops it from re occurring.
Dave

[MarinaCoupe]

Yes I get it Dave, I'm thinking of doing it on my Coupe's starter.




Chris

[david painter]

That would be a great idea just like fitting relay when uprating headlamp bulbs so not to burn out dipswitch. Thinking about it BL just disconnected starter trip wire and run additional harness to inhibitor switch and plugged back into main loom to operate starter and reverse lights as a cheap and cheerful after thought !!
Dave

[SLOW ITAL]

Been watching this, agree with Dave & Killroy, + extra relay sounds good.
Sent from sunny Ibiza...
Gil...

[MARINAMADBAZ]

The inhibitor switch feed comes of a block connector 2 pin male and female around the fuse box area its a thick red and white feed wires ,it has 2 wires, on a manual the block connector is just a link/loop wire basically back onto itself,you could check the inhibitor switch by undoing this and putting a loop wire in this as for a manual,this will test the starter and the other wiring but the car will start in any gear so be careful make sure its in P or N
Best regards
barry

[david painter]

That's how I thought it would work, bit of an after thought on the part of BL, penny pinching. My MG has a starter relay so if auto option was used, inhibitor switch was wired through that/ Don't see why they did it different for the Marina other than to save the cost of a relay
Dave

[Kilroy]

What I have found also is the existence of two different types of inhibitor switch.
One is quite sturdy and heavy duty looking - most OEM setups have this type.
The other is much lighter in construction while being the same shape.
Both fit easily, but I think the lightweight item is designed for a different car which only needs light current application - so has trouble with the Marina solenoid.
Having said that - the OEM type can still develop contact problems over the years.
I have never had any issues with the relay setup after many years use - despite there obviously being some limitations somewhere in the switch or circuits.

Worthy of note that the same inhibitor switch operates the reversing lights when fitted - so it has 4 terminals.
Also worthy of note - the switches became prohibitively expensive many years ago, so look after them...

[david painter]

James Paddock Chester has the switch for the BW 35 type box screw in type in stock £34.00 inc VAT the later Quadrant type on BW 65 boxes seem to be available from several Automatic Transmission parts suppliers several types listed depending on wire/plug configuration
Dave

[mickthefitter]

I have worked on my car today, I was going to upload photos but no time tonight as I've a long day ahead tomorrow. Basically I've tidied up the bodgery, checking soundness of connections into those nasty domestic terminal blocks, putting fresh insulation tape over them, cutting out sections of bad wire, but most importantly while my 'hot wired' starter remains I've run the +ve battery side of the starter button through a 35 amp fuse. There's an additional fuse box on my car in the engine bay, the old basic Lucas type found on Minis, which someone who put a Kenlowe fan on installed. There was an unused fuse position and I extended the wiring to that. Not as good as a relay, but in the short term, I hope I've removed the immediate fire risk. Additionally I can tell you this - I tried starting the car (with the key) in 'D' - it does nothing. No click, nothing. As I correctly recalled from my white 1.8 SDL auto in the 80s. So when my car goes 'click' in 'P' and won't turn over, it can't (I think) be the inhibitor switch at fault. This fault is probably why a new switch was bought and fitted by the previous owner, but it didn't cure the fault. Also, while I had my manuals spread out, I picked up on a paragraph which said the inhibitor switch on the Borg Warner Type 65 transmission is not adjustable - which discounts the one on my car needing any tweaking because it was fitted wrong. I would not be surprised if the old grease covered inhibitor switch I found in my box of spares is fully functional. The car might have even had its new starter motor fitted 2-3 years ago because of this same fault! So unless I can find any evidence to the contrary, Kilroy's statement about some connector blocks somewhere in the starter circuit getting more resistive with age seems to be the likely cause of my cars problem. Of course sometimes it starts okay on the key - and usually if the engine is hot, it turns over very quickly!

[SLOW ITAL]

I think you've come round the full circle, as Dave has stated you need to find the problem
In your srarter circuit first & repair that, loose that push button & wiring then go for Killroys
Relay set up which will stop any further problems in the future.
As the guys have said, the connecter blocks are the most likely culprit or burn't wiring,so you should trace it OK.

Ive got a 1.3 mk2 auto & i will be fitting Killroys mod, but will take the earth wire at the
Relay to a switch in the cab & then earth it, giving me an extra engine cut off.
No earth no start...
Gil....

[Kilroy]

Proviso.

I should have stated earlier that all my comments relate to the Borg Warner 65 auto, as all the Mk2 and Mk3 Marina autos I have experience of have such.

I have had similar solenoid engagement problems on both Mk2 and Mk3 autos, and both have responded successfully to fitting a relay in the starter circuit.

Regarding Gil's extra cutout - I have added a killswitch circuit to most of my Marinas. I should probably kill you all after telling you this - but I am feeling benevolent tonight so you are all safe.
And a long way off...
I alter the wiring in the engine bay and run a 2-core wire to a switch concealed under the dashboard but within easy reach of my hand.
I connect one wire to the distributor and the other to the negative side of the coil - replacing the wire that used to go between these two points.
This switch will prevent any attempts to start the car when off - even if somebody hotwires the ignition or bypasses the ignition switch.
Even though power will then reach the coil - it cannot reach the points - so the car will not start.
I have had two cars that have been attempted to steal - and both ended up at the bottom of the hill I lived on because they would not start.
I simply walked down in the morning, turned the switch on and started the car.
On one such occasion, my killswitch was hanging in the parcel tray behind a rag as I had not finished installing it..!

The reason I have been fitting such switches is because I can open the door of any of my Marinas with a nail file...

[mickthefitter]

I think you've come round the full circle, as Dave has stated you need to find the problem
In your srarter circuit first & repair that, loose that push button & wiring then go for Killroys
Relay set up which will stop any further problems in the future.
As the guys have said, the connecter blocks are the most likely culprit or burn't wiring,so you should trace it OK.

Ive got a 1.3 mk2 auto & i will be fitting Killroys mod, but will take the earth wire at the
Relay to a switch in the cab & then earth it, giving me an extra engine cut off.
No earth no start...
Gil....

My work when I'd got the time yesterday (on a Bank Holiday, and not for the rest of this week at least) was primarily to address Dave's alert about the fire risk of having a permanent unfused live wire attached to the starter solenoid, interrupted solely by the add-on push button. And to tidy up some really shabby cut-about wiring that I'd only just become aware of when trying to trace through the wires from the push button. I certainly haven't completely rewired the car to a concours standard and neither have I traced the fault, but I did what I could with what I'd got when the shops were closed and I couldn't go out and buy anything. My standards are at least higher than peeling insulation tape, tape over chafed outer insulation, loose screws in connectors, and splayed out conductors shoved into terminal clamps, and once I'd been made aware of it, not having a fuse in the hot-wired circuit. When time allows I'll get some proper automotive connectors and neaten everything up further.

But correct me if I'm wrong, but has Kilroy not exactly traced and repaired the source of the solenoid malfunction, but merely by-passed the problem with his mod? He said in his first post on this subject that the original wiring is perfectly happy to operate the relay at the turn of the ignition key, and then the full power is supplied to the solenoid via the relay through his wiring mods, whereas his suspicion is that the original wiring is losing power along the way and will not properly operate the solenoid. I don't think the suggestion is that there is some melted and damaged wiring or multi pin connector somewhere along the way, but that over time aged wiring and connectors have dropped in their efficiency.

I can certainly check the connections at the inhibitor switch when I've time to get the car up on ramps, but as I've been saying, I'm no electrician, and finding a fault somewhere within the loom is probably out of my scope. Plus, the history of my car suggests it has defeated others before me!

[SLOW ITAL]

I take your point, no criticism intended, you've done well with the time you had,
Im sure you'll continue to look for the problem...
I don't think you need to get into the harness, just a visual check of the connections will tell you if they are corroded or burnt, then once repaired Killroys mod will stop any further problem...

Killroy, agree with your ign cut off , did the same but only took a single wire & soldered onto the black neg cable to the coil, but further back in the harness so its concealed.
then fitted switch under dash & earthed switch there. In the on position & trying to start, the spark goes to earth, no start, +in off position no possibility of open circuit (same as your way ) .
But like your starter mod & cutting the earth to the relay with a switch will give me a second
Security cut off, any low life will just think the batteries flat ( hopefully)...
gil...

[Kilroy]

Gil - if I understand your explanation - you have fitted a switch in parallel with the points - so with the switch 'on' it is the same as if the points are permanently closed.

If so - the coil will be drawing stall current for as long as the ignition is on.
It will get very hot to the point of failing should that condition continue for too long.

The end result however is exactly in line with what I thought - anyone trying to start the car would have spent too long and give up rather than draw attention.
I was most fortunate in both cases that the car was not vandalised - although they left the door open..

[SLOW ITAL]

Hi Killroy,
I agree might be a problem if they just ran off & left it with whatever trick wiring they used
To defeat the ign left in place.
I'll try leaving switch on & check the coil temp after a few min's . Might need to tweak it a bit.
Thinking was, wanted to use a switch which would have no current passing through while engine running, using a switch to make the circuit gives slight chance of it failing at some point
( OK thats not too lightly) , but thats why i went that way.
Havn't had one of mine taken but back in the day my sister lost her cortina estate in a multi story, she found it 2 levels down no damage, flicked the 2 switches &went home.
I'd cut the ign & starter circuit,they must have thought battery flat & shoved it down ramp but no go so they gave up...
They are elementry but do stop the chancers.
Of course if they know what they're doing & they have time nothing really will stop them.

Thats a good point about the current though, i'll look at it again, (might be another relay job)...
got a few days off in ibiza so its time to hit the pool, ( might blow the froth off a few while im there)
Gil...