rich
Well-known member
CAN I do it, with out damage?
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Running engine with ALT disconnected
- Thread starter rich
- Start date
chippie
New member
If you mean electrically disconnected, the received wisdom is no,although I have disconnected the battery from the leads on car engines with no ill effect but only at idle speed.
If you mean not connected by the v belt I dont see why not as long as cooling water is still circulating.
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If you mean not connected by the v belt I dont see why not as long as cooling water is still circulating.
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andyball
New member
As always....opinions vary
Long thread<A target="_blank" HREF=http://www.ybw.com/cgi-bin/forums/showflat.pl?Cat=&Board=pbo&Number=447212&page=&view=&sb=&o=&vc=1>here</A> covers it.
My view is that if external reg & unconnected, fairly obviously no field current can flow, so no output to speak of.
If internal reg, possible for residual magnetism to start it charging , but field coil draws several amps & will stabilise output enough to allow the regulator to do what it always does & regulate.
an internal reg. with battery sensing, might have a problem.
DON't disconnect it if the engine's already running.
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Long thread<A target="_blank" HREF=http://www.ybw.com/cgi-bin/forums/showflat.pl?Cat=&Board=pbo&Number=447212&page=&view=&sb=&o=&vc=1>here</A> covers it.
My view is that if external reg & unconnected, fairly obviously no field current can flow, so no output to speak of.
If internal reg, possible for residual magnetism to start it charging , but field coil draws several amps & will stabilise output enough to allow the regulator to do what it always does & regulate.
an internal reg. with battery sensing, might have a problem.
DON't disconnect it if the engine's already running.
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oldharry
Well-known member
Connecting or disconnecting the alt while it is running causes a voltage surge in the alt which blows the electronic regulator. You may just be lucky and get away with it at tickover when output is low. There is no theoretical harmn in spinning an alternator without a load connected, although in practice its not a particularly good idea as the regulator may be carrying much higher voltages than intended, and any mishap could blow it.
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VicS
Well-known member
Yes, but what you must not do is disconnect the alternator fron the battery while it actually running.
Can you not remove the drive belt, or does it also drive one of the coolant pumps? Even if this is the case you can run for a while without coolant circulation especially if you can keep an eye on the temperature, assuming you have not also disabled the temperature gauge!
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Can you not remove the drive belt, or does it also drive one of the coolant pumps? Even if this is the case you can run for a while without coolant circulation especially if you can keep an eye on the temperature, assuming you have not also disabled the temperature gauge!
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halcyon
Well-known member
Technically yes, as you have to supply power to the rotor to start generating power, if this is disconnected then no output.
But then I do not offer any warrenty with this advise, as anything could go wrong.
think that covers me.
Brian
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But then I do not offer any warrenty with this advise, as anything could go wrong.
think that covers me.
Brian
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rich
Well-known member
Thanks every one. I will take the belt off, i just want to fire them up as they have been in my workshop all winter.. only the oil pressure is connected, ahhhh do you have too bleed the oil press pipe at the gauge??????
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oldharry
Well-known member
OOOPS!
Just did it - ran my engine for over an hour with the alt disconnected! Reconnected and all working fine - so proving its OK (at least on my set up). But I still wouldnt entirely recommend it!
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Just did it - ran my engine for over an hour with the alt disconnected! Reconnected and all working fine - so proving its OK (at least on my set up). But I still wouldnt entirely recommend it!
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