Classic cars forum & vehicle restoration.

[fiatguy23]

Hi all,
First time user on a forum so here goes nothing! We own my grandfathers 1925 Morris bullnose roadster and of late we have been having some electrical issues. The car has been restored since the 80's by my poppa and I'm not sure if the problems were around when my poppa had it but its too late to ask now. Anyway, it keeps blowing its rear brake lights and we have gone through two flasher cans through a 12 month period. At one stage, we lost headlight, parkers and brake lights all in one hit! The dynamo doesn't seem to be over charging, it stays on the maximum output of 9 amps at running speed. This is normal according to the book anyway... If anyone can think of any reasons why this is happening that would be great as it is quite frustrating when the blow while out on the road! Cheers

[roverdriver]

Hello fiatguy. The flashers are definitely a modern addition, and I would guess that the brake lights are too. I would suggest that these items have been wired into the car in such a way that they are getting too much current, but without examining the car, I couldn't say more than that. Hopefully an electrical guru will come along with a more positive answer.

By the way, whereabouts in Oz? I am in Victoria, South Gippsland.
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Dane- roverdriver but not a Viking.

[fiatguy23]

Hi roverdriver, thats what I have been thinking too, although I checked the voltage across the battery with and without the car running, and all seemed fine. The dynamo had it charging at around 13.3 volts which seems, if anything, lower than what would be expected. But then again I am just going by what modern cars run at...
I am assuming there is no real wrong way to supply power to these items, whether it comes directly from the battery or from the dynamo feed its all the same thing really cos its all connected. Is that correct?

I am in the Barossa Valley region in south australia btw

[roverdriver]

As no-one else has offered any suggestions, all that I can say with my limited knowledge of electrics is this-

13.3 Volts should be adequate to keep the battery charging. I don't know specifically about your Morris, but some cars of the period did require the generator (3rd brush type) to be adjusted for more current if prolonged night-time running was planned.

I agree that in theory there is no really 'wrong' way to wire the items so that they get too much current, but strange things can happen with wiring. I would however do a careful check that all items are properly earthed. Poor earth connections, especially when the chassis is the main earth, can create all sorts of difficulties. I would be tempted to trace all wires and check them, but also remove, clean and reassemble any chassis earths,

I do hope that that is some help, and hopefully someone with specific electrical or Bullnose knowledge will come forth.

Many years ago I took the family for a nice tour through the Barossa Valley, visiting Kapunda, Angaston, Birdwood, etc., etc., using our 1928 Model A Ford. Alas I don't have the A any more.

Dane.
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Dane- roverdriver but not a Viking.

[fiatguy23]

Thank you for that you had some good points there. I'll pop it up on blocks and have a good thorough look at everything, the car has been on the road for close to 30 years so there could even be a few bare spots here and there. It just means taking it off the road for a while, but I guess that's the joys of old cars.

[47p2]

Also check for any chaffed wires, especially where they run through the bodywork as they could be earthing and causing problems.
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ROVER
One of Britain's Fine Cars

[MVPeters]

See if this helps:
When you say "the brake lights blow out", do you mean the bulbs fail? all at once, or one at a time? When they are replaced, is everything OK, at least for a while?
When you say you lost all the lights in one hit, I'd say that indicates a single point of failure - a wiring problem affecting all the circuits involved. & this would be on the old, original wiring, not necessarily the added circuits - depending on where they are connected.
The connection point for any circuits should be to the regulator or fuse box, not to the dynamo charging circuit - leave that alone.
Don't confuse voltage with current; 13.3 VOLTS is OK, though perhaps a little low - I wouldn't worry about it for now. 9 AMPS is also OK, though a little on the high side once the engine is warmed up & with no lights on.
Does the lighting or ignition switch have day & night positions? There's a resistor behind it that keeps the charging rate down when you don't need it.
I'd connect a volt-meter to somewhere on the dashboard & drive around for a while & watch it & the ammeter; you should see an initial charge rate quite high, dropping back as the battery re-charges. Turn the lights on & see what changes. Watch for violent changes, which would indicate loose connections or short-circuits.
There are other Bullnose owhers on here who may be able to offer more specifics.
I hope this helps.
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Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'

[fiatguy23]

Hi Mike,

Yes, the bulbs do fail, and I am assuming it is all at once too. They seem to be fine for a while after new ones are installed however they do blow after a few trips in the car. The bulbs used in the brake lights are the type that resemble a fuse (couldnt think of any other way of describing them) with a single filiment. Are these supposed to run at a higher voltage than 12?
I haven't yet traced where the lights are connected to but I would assume they come strait from the battery, the car doesn't really have a fuse box!
There is no switch for day/ night settings, simply an on/ off mode for the charging circuit. The dynamo also doubles as the starter motor, so turning the dynamo off stops it charging and allows the starter motor to be opperated when the button is pushed. Reading the manual forthe car it basically says that the battery does not need to be charged all the time and it recommends to turn the charging circuit off if on a long trip for a period of time. So I'm assuming that means there is no resistor or regulator that controls the amount of charge. There is however what they call an 'electromagnetic cutout' which is basically a primative form of a diode, just stops the battery from discharging I think.
I have had the volt-meter connected to the battery while the engine was running and brought it up to temperature. Everything seems fine really, the lights do lower the level of the battery but nothing more than what you would expect. The dynamo only starts charging after it reaches a certain amount of rpm, and this is normal according to the book anyway.

Thanks for your input,

Brodie.

[Roger-hatchy]

Vibration can also be the cause of bulb failure.

When I was still working failure rate of trailer bulbs on our 20 foot container trailers, when running light, was a nighmare, quite often a full set of bulbs twice a night.

Just a thought.

Roger

[fiatguy23]

Problem solvered!

Found a wire that had chaffed quite badly in the front spring hanger, hence causing it to short out sometimes if a big enough bump was hit! Easy fix!

Also took of the tow hitch and the trailer plug that was installed on the car; there is no way the car could tow a trailer and it was just extra wiring that need not be there.

[roverdriver]

Well done, Fiatguy. Pleased you found it and fixed it so easily.
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Dane- roverdriver but not a Viking.

[NONORT]

Hi I am new to this forum but have some experience with a 1924 Bullnose. Thankfully you have found your problem and fixed it. But you may like to know. The two switches on the dash are removable with the use of a screw driver the front panel will then come off leaving the amp meter behind. Having removed this you will see the wiring as such in front of you. There is a fuse to the left of the amp meter and a place to store some spare fuse wire. If you are lucky you will find a wiring diagram on the back of the face plate that you removed if not there is one in the book by Jarman and Barraclough 'The Bullnose and Flatnose Morris' available from Flea bay. Your symptoms of blown bulbs are synonimous with over voltage. To charge a battery you have to put in more volts than you end up with. This will over stress the bulb filliment. Taking the power from the correct place on the dash panel will over come this as the voltage will be regulated. Some people have had the regulator cut out go bonkers and send the voltage way over the top for a few seconds, more than enough to blow every bulb that is switched on at the time. The charge amperage is set by the third brush in the starter / dynamo. I hope this can help sort out the problem for you. If you require a wiring diagram I can email one to you.

[fiatguy23]

Hi NONORT, that was our first place to look to see if anything obvious stood out but all seemed fine. We actually traced allthe wires back and found that the power for these acessories came direct from the battery so I can't see and problems with that. So far the car hasn't missed a beat, and all the lights seem to be working as they should

If something does pop up again I may have to inspect the dynamo but I will see what happens. I think I actually have that book that you mentioned too, its got a blue cover (i think?) and covers everything!

[NONORT]

Hi Guys and Galls
Spoke to soon took the bully out for a run on Saturday blew the fuse and lost all the charge in the battery. Got a short somewhere. Thing is in the dim and distant past I recall seeing a diagam of an electronic cut out unit that fits in place of the old one. Any chance anyone out there has a copy of the circut diagram?
Living in hope no nort.

[fiatguy23]

Hi nonort,
I do vaguely remember reading this some where but I can't remember! I shall keep my eyes peeled and keep racking my brains