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Warning light


Roxylass

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The warning light wasn't going of when I started my lister sr2.

Replaced with a new one still wasn't going of.

Had a mechanic look at it couldn't figure it out

So he fitted an exciter switch.

So when I turn the key now i press the button and the warning light comes on.

Start the engine press the button and the warning light goes off.

Is this an acceptable practice.

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The warning light wasn't going of when I started my lister sr2.

Replaced with a new one still wasn't going of.

Had a mechanic look at it couldn't figure it out

So he fitted an exciter switch.

So when I turn the key now i press the button and the warning light comes on.

Start the engine press the button and the warning light goes off.

Is this an acceptable practice.

The alternator on that engine would be driven by the camshaft which rotates at half crankshaft speed. So it sounds like you have the small diameter pulley on the camshaft. To get the proper output from the alternator a larger diameter camshaft pulley is needed, a 9, 10 or 12'' one. You would not need the exciter switch then, just a normal 2w or so warning light which would excite it.

 

Mechanics that don't know these engines often think the camshaft IS the crankshaft, because its thick and beefy.

 

Nothing wrong with an exciter switch but a bigger wattage warning light bulb would probably do the same thing. 5 or 6 watt.

Edited by bizzard
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M'lud B'zzard is absolutely correct, but for folks unfamiliar with engines manufactured before the dawn-of-time, perhaps the key point is that you need to spin the engine up-a-bit to get the alternator to start charging, and the light should go out, without the need for a shorting switch.

IME the shorting switch often gets left on - and that will flatten the engine battery if left on for long enough (done it...)

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Yes problem started after new belt fitting

Where could I purchase a 5/6watt warning light.

Cant see any on eBay.

It would be fitted with a much lager bulb holder than the usual tiny one which you probably have , which will mean enlarging the hole for it. Car spares shops and motor factors would have them. But do you have the large diameter drive pulley on the camshaft or the small 5'' or so one?

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It would be fitted with a much lager bulb holder than the usual tiny one which you probably have , which will mean enlarging the hole for it. Car spares shops and motor factors would have them. But do you have the large diameter drive pulley on the camshaft or the small 5'' or so one?

 

Another bulb or resistor in parallel with the original lamp can be used if a higher wattage bulb of the same style can't be found to fit the existing lamp holder.

  • Greenie 1
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As an initial check, I'd see if the batteries are being charged up with the engine running. Check the voltage is at least above 13 volts (higher than when engine is not running). Just wondering if alternator is playing up or a connection was disturbed when the belt was changed

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Here is a couple of pictures

You do have the small diameter pulley. It would excite and charge so much better with the large one. That W/Light wire from the alternator looks stretched and a bit thin, strands maybe broken in it..

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The main B+ connection should probably have one from battery, one to control panel and one to the alternator. Your problem has not been caused by sudden shrinkage of the pulley and you shouldn't rely on a bodge carried out by a bloke who doesn't know what he's doing.

Funny this should come up now, I have just refitted my 24 volt domestic alternator following repair. started the engine all fine ant then noticed the "Ignition" light glowing. I had caught the field connection on the 12 volt alternator mounted a little way above the 24 volt one. quick wiggle and all fine again.

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The battery shows 13 volts before starting

Engine running not even half throttle it's showing 13-50 13-60

 

I would like to see above 14 volts a short time after starting.

 

Most alternators don't charge below 2,000 rpm, do the volts increase at higher rpm?

 

If you switch the exciter switch off does the lamp come back on?

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Once I start the engine I switch the exciter off.

And yes it stays off.

 

 

With the boat sitting out the water just now on blocks

I am not going to be giving it full throttle

What I think you have is a work around for a problem which is still there and could get worse. So in answer to your original question, no, I don't think it is ideal.

 

I suggest you get all of the wiring checked out by a good engineer and have the alternator tested. As mentioned, it should give you over 14 volts if it's working properly and testing will show whether the DC output is smooth and correctly rectified.

 

Also as mentioned, a bigger pulley on the crankcase end would help but I assume everything was fine up until the fault.

 

Once the fault has been rectified (so to speak) it might be best to remove the work around to simplify the circuit and prevent that causing a future problem. I hope you get it sorted.

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