Yanmar 2gm alternator

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rubbishman

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Hi all my alternator a Hitachi 55 amp got sprayed with diesel it now does not work put on a spare one and that works so it is probably the alternator my question is will the windings or more the lacquer on the windings be damaged I have looked and the lacquer is not complete does this matter I want to get a man to look at it but do not want to pay him to look if it is irrepairable
 
rubbishman said:
Hi all my alternator a Hitachi 55 amp got sprayed with diesel it now does not work put on a spare one and that works so it is probably the alternator my question is will the windings or more the lacquer on the windings be damaged I have looked and the lacquer is not complete does this matter I want to get a man to look at it but do not want to pay him to look if it is irrepairable
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Strange. I am wondering what caused it to stop working. I don't think anything is actually damaged, let alone the winding coating. The most likely (still rather unlikely, actually ;-)) cause could be the diesel stops the excitation brushes making proper contact with the rings. I's suggest to wash (soak) the whole thing in petrol - let dry properly before experimenting with it further :-). Shouldn't cause any harm and may bring it back to life.
 
jiris said:
Strange. I am wondering what caused it to stop working. I don't think anything is actually damaged, let alone the winding coating. The most likely (still rather unlikely, actually ;-)) cause could be the diesel stops the excitation brushes making proper contact with the rings. I's suggest to wash (soak) the whole thing in petrol - let dry properly before experimenting with it further :-). Shouldn't cause any harm and may bring it back to life.
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Thanks for replying,have had it to bits and cleaned it.
 
I can't see why diesel would damage the alternator. The only scenario I can think of is that the diesel dissolved away and displaced some grease onto the slip rings. Spraying with diesel wouldn't be vastly different to spraying with WD40.
 
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The thanks everyone for your replies, I have now had the thing apart again and sprayed it with a local cleaner available in New Zealand(I am English but I'm just waiting out the cyclone season here) but the thing still doesn't work. I have talked to a couple of local mechanics and they are of the opinion that's spraying an alternator with diesel will mess it up. Personally I don't claim to be a mechanic although I have done a couple of engine changes, head gaskets on specials years ago and of course the usual misspent youth of working on 2-stroke motorcycles. So as I don't know what's wrong with the alternator I guess I will have to pay a man to look at it which is not a cheap option in New Zealand, I was quoted 640 pounds, not dollars, for a new one but I am temporarily living in the land of $10 Cauliflowers. But perhaps some kind soul on the forum knows more about testing alternators, thanks, Colin.
 
coopec said:
You say it doesn't work but have you tested it properly? I ask this because I am aware that an alternator won't work unless it gets excited (Sound familiar!)
Apologies if I am stating the bleeding obvious.
http://shoptalkforums.com/viewtopic.php?t=135956

Maybe the experts here could comment on that theory?
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I see your point but the alternator I have on there at the moment which was my spare ,works fine. So I guess that one, the working one that is, is getting enough excitement in it's life to make 14 something volts, cheers Colin.
 
The Yanmar 2GM alternator is an Hitachi unit which you can find with the same mounts and often as higher current versions on some Japanese cars. Try a breakers.
 
coopec said:
Have you replaced the alternator that is working with the one you are trying to repair and wired it up the same way? Maybe it will work if it is getting excitement from the boat battery?

https://forum.ih8mud.com/threads/exciting-my-alternator.435524/

Clive
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Yes that's exactly what I've been doing. So I take the working alternator off the engine replace it with the non working alternator ,the original, the one that got sprayed with diesel. So now I have the original diesel sprayed non working alternator on the Yanmar 2gm and when I start the engine it puts out no charge if I put the spare alternator back on the engine it works fine the spare alternator makes a charge of 14 something volts. Thanks Colin.
 
Yes, you've done everything correctly as far as I am concerned. Maybe you must do what Savagedog says and go to a wrecker (breaker). But why can't it be any alternator of similar specification?
Cheers
Clive
 
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coopec said:
Yes, you've done everything correctly as far as I am concerned. Maybe you must do what Savagedog says and go to a wrecker (breaker). But why can't it be any alternator of similar specification?
Cheers
Clive
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All the alternator has to have spec wise is the same frame and return ! Replaced my hitachi 3 years ago with a higher output genericfor £150 works fine

John
 
Yes John my Perkins 4 108 (marinised ) has the same 12V alternator as a tractor would have but I am going to replace it with a 24V 60 amp alternator off a Toyota Hino bus. I'll have to think hard how to drive it maybe a duplex "V" belt drive or perhaps a serpentine belt. I'll have to get advice as to which way to go. I am also going to get advice as to whether I can use an air-conditioner clutch to switch the alternator on/off.
Clive
 
coopec said:
Yes John my Perkins 4 108 (marinised ) has the same 12V alternator as a tractor would have but I am going to replace it with a 24V 60 amp alternator off a Toyota Hino bus. I'll have to think hard how to drive it maybe a duplex "V" belt drive or perhaps a serpentine belt. I'll have to get advice as to which way to go. I am also going to get advice as to whether I can use an air-conditioner clutch to switch the alternator on/off.
Clive
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I guess the aircon clutch would do the job O.K., can't see why not. What eludes me is; WHY? Am I missing something?
 
Maybe I worry unnecessarily but I think a 24V 60 amp alternator charging flat batteries would take a bit of power from a 39hp (continuous) engine. If I was in a tight spot and needed full power I'd like to be able to flick a switch to disengage the alternator.
Clive
 
coopec said:
Maybe I worry unnecessarily but I think a 24V 60 amp alternator charging flat batteries would take a bit of power from a 39hp (continuous) engine. If I was in a tight spot and needed full power I'd like to be able to flick a switch to disengage the alternator.
Clive
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Would the air con clutch be man enough to transmit the torque required by the alternator at full output ?

A simpler way of de-loading the alternator might be with a field interrupt switch.
 
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