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Suggestions for power take-off for screenwash pump


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I've had three loom fires.

The Herald, on its last journey before being scrapped, shorted out some wiring behind the dash. Lots of smoke then it burned out and that was it.

The GT6, many years ago, had a power wire for a radio that hadn't been fitted since before my brother owned it. The fuse holder came undone, the live end dropped and the metal bit touched the floor. Lots of smoke from between my legs! I quickly pulled over, removed the offending wire from the ignition switch, and continued my journey. Fuses may be your friend but inline fuse holders sometimes aren't.

And then there was the Dolomite. An 1850 that had been re-shelled in a 1500HL body, and not terribly well. The main power distribution - connecting the battery, alternator, and then the pre-fuse stuff - on a 1500 is an H-shaped piece of copper in a thermoplastic housing (with four big Lucar connectors plugged into it). This is mounted on the LH inner wing. Since my car was an 1850, that location is directly above the exhaust manifold. The fixing lug broke. I'd driven down to church and parked. I came out an hour later and found the car had no battery power. On opening the bonnet I saw that said terminal block had fallen off the wing, landed on the hot exhaust manifold, melted, then shorted the battery via the heavy gauge main supply wire and the engine earth strap. The loom had caught fire, burned until the main supply wire broke, at which point there wasn't enough heat being put in to sustain a fire in the electrical insulation material so it went out. I managed to repair the car with a single 2ft length of 40A brown wire. I also re-made the housing for the power terminal block in a less vulnerable material.

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Wayyyyy back - yes, that far back - I converted a positive earth Herald to negative earth. "Don't believe any of the stories about the fan now sucking instead of blowing" ran the article "but your wiper motor will now spin in the reverse direction. After years of use it has bedded in by running in one direction, so in order to get it back to where it should be and running smoothly again, change round the wires at the wiper motor."

Ever done that? Nothing happens for a minute then you see the smoke coming up from under the dashboard.

So: after sulking for a bit I removed the entire loom, labelling the connections as I did so. The loom was repaired and the melted sections replaced. Then I put it back, exactly as before.

It melted straight away, exactly as before.

Now you know why I'm wary of ANYTHING to do with the wiper circuit, and will debate for hours before going near it.

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1 hour ago, Colin Lindsay said:

"but your wiper motor will now spin in the reverse direction.

I don't know where you read that but the author of the article was an idiot who had never looked at a Lucas wiper motor. It cannot have its wires swapped, as you found out the hard way, and is not a permanent magnet motor anyway so will NOT run backwards if the polarity is swapped. Triumph did not change the wiper motor or any part of the wiper circuit when they changed the Herald from positive to negative earth.

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20 minutes ago, NonMember said:

I don't know where you read that but the author of the article was an idiot who had never looked at a Lucas wiper motor. It cannot have its wires swapped, as you found out the hard way, and is not a permanent magnet motor anyway so will NOT run backwards if the polarity is swapped. Triumph did not change the wiper motor or any part of the wiper circuit when they changed the Herald from positive to negative earth.

Shame its not ac 3 phase, very easy to change direction. 

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11 hours ago, NonMember said:

I don't know where you read that but the author of the article was an idiot 

I think I might have determined that by now. :)

It was part of a type-written set of 'how-to' instructions that came in a huge pile of paperwork in the car, so no idea where it originated and it's since been safely disposed of. It also included gems like 'the bulbs will now work back to front so may not be as bright as they were originally; consider a new set of negative earth bulbs all round' and there as also a paragraph on swapping the horn terminals around so that they would be as loud as before.

Back in the day when my entire tool kit was a woodsaw, a hammer and a spanner, that sounded wonderfully knowledgeable.

 

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2 hours ago, NonMember said:

Are you sure it wasn't published on April 1st?

It may well have been. Seemed like a print-out from a black and white Club Magazine of some description... but after the harm it did to my loom it went in the bin, I remember pouring water over it to soak it so that it couldn't be dug out and reused at a later date... :)

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9 hours ago, Colin Lindsay said:

It also included gems like 'the bulbs will now work back to front so may not be as bright as they were originally; consider a new set of negative earth bulbs all round' and there as also a paragraph on swapping the horn terminals around so that they would be as loud as before.

That want`s fileing under the same heading as "A Long Stand", "bucket of 1/2" holes" (or steam), Tartan Paint?. Every Aprentice fell for one or the other.

Pete

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Ok. I am going to lead myself wide open to abuse and ridicule here, but reading the comments about battery terminal reversal (+ earth to - earth) got me thinking...which as you all know is dangerous. At a show a couple of years ago, I bought one of those battery dis-car-nect thingies, which sat around in the spares box for some time. Then, when I did my fuse box upgrade I finally fitted it... to the negative terminal of the battery, as that's where I had seen others fitted and also on some yootoob vids. Now, all this talk of fires etc got me thinking that I should have fitted it to the positive terminal so that it isolates the battery from the car totally. How I have connected it up, leaves the danger of reconnecting the battery by accident with a spanner etc from body to battery earth, and before someone says it, yes, I know that I should totally disconnect and remove it before doing any work!!!! Is mine wrong or right??

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1 hour ago, Badwolf said:

How I have connected it up, leaves the danger of reconnecting the battery by accident with a spanner etc from body to battery earth,

On the contrary, that is precisely why you are recommended always to fit the discarnect in the earth (negative) lead.

With the battery positive disconnected but the earth still there, you could drop a spanner on the battery and, if unlucky, have it land on both the battery's positive terminal and the bodywork. This forms a dead short from battery +ve, through the spanner, then the body, then the earth strap, to the battery negative. Shorted battery, huge current, bang!

Now suppose it's the earth lead you've disconnected. Dropping that same spanner now connects the car's main power to earth... but there's no power on it because the battery is already disconnected from the car's earth. The battery negative terminal sits at -12V quite calmly and without any issue. Were you instead to drop the spanner on the -ve post to body, all you're doing is re-connecting the normal circuit, so again all's well.

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So couldn't simply putting a piece of fabric or cardboard on the top of the battery offer the same safety when working under the bonnet?

I think I'll make myself a designer battery protection cover from an old shoe box lid.

NO! You can't start quoting 'The shoe box sketch'

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17 minutes ago, Chris A said:

So couldn't simply putting a piece of fabric or cardboard on the top of the battery offer the same safety when working under the bonnet?

Way too practical and simple... I need a 3D printed, one off, hand-sanded cover made of extruded bamboo ...

😄

 

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17 hours ago, NonMember said:

With the battery positive disconnected but the earth still there, you could drop a spanner on the battery and, if unlucky, have it land on both the battery's positive terminal and the bodywork. This forms a dead short from battery +ve, through the spanner, then the body, then the earth strap, to the battery negative. Shorted battery, huge current, bang!

My late father had a one ended (previously 2 ended) spanner that a workmate had dropped across the batt terminals of an aircraft 'Trolley Accumulator' - basically a bank of 100AH batts in a trolley to start a/c on the ground. When the spanner shorted the batt out there was indeed a huge bang and one end of the spanner basically vapourised ! 😕

Gav

 

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