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Discussion Starter #1
Hi all

I'm wondering if someone could possibly help me with a problem I'm having.

I changed the alternator today as the pulley fell off the last and destroyed the alternator shaft. I picked up a recon and installed but i'm having problems.

The 'alternator workshop!' alongsde the battery warning is intermittently showing up, especially with higher revs. The car also seems to be holding back slightly when driving. I've just read an article on 'limp' mode and wondering if a faulty alternator could cause this.

Does anyone know the voltage I should be reading off the alternator, or cutting to the chase, is the replacement alternator I picked up faulty

Thanks for giving this a read
James
 

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Yes, low voltage can even cause transmission problems.

About 14V is right with the engine on, about 12V is right with the engine off. I've had defective autozone alternators, it's possible you got a defect too. Take it to the auto parts place that sold it to you, they might have a tester that can check it on the car for free. A garage will charge you $40-50 for that check.
 

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Discussion Starter #3
I posted this same question on another forum some time ago with no responses, so thank you for your quick reply, much appreciated.

I'll put a volt meter on tomorrow and see what readings I get off of it.

Regards
James
 

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Also turn on the electrical load, with headlights, taillights, seat warmers, fan, radio on, it shouldn't go below 12V with the engine running. About 13.6V with engine on is also OK if you don't get the 14V.

Also check the pulley, it sounds like the pulley is bad. The pulley should freewheel one way. The reason it does this is it prolongs alternator life. The jerky diesel power pulses and other stuff are dampened by a alt clutch pulley.

Aternator workshop means bad pulley, bad voltage regulator (inside the alternator and means bad alt), bad brushes, bad connection, etc. It likely means the pulley or reman alternator is bad.

Also, make sure the pulley is of the same type. The wrong pulley can cause strange problems. If your original pulley is still good try that if the alt checks out OK. Or you could put on a solid pulley that won't fail. Although the alt life should, in theory, be shortened, a bad alt pulley can also cause a no start condition and be just as bad. So your choice. Any vendor should have the correct pulley part number for your year/alt part number.
 

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Discussion Starter #5
Ok thank you, some good information there. Unfortunately I don't have the orginal pulley as it completely crumbled inside and handed it over with the alternator for sur charge. I'll give them a ring first thing Monday and see if they still have it. By eye it did seem the correct type.

I'll get up early tomorrow and do what you have suggested and post back

Thank you for your time
James
 

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Hi all

Ok I put the Volt Meter on this morning. I think the problem has become clear.

The battery without engine on is sitting at exactly 12.60V.

However with engine on I'm getting readings of up to 16.5V. With electrical load and increasing revs there wasn't really much of a change. The voltage seems to fluctuate but a majority of the time will sit in the 15-16V area.

The engine is also quite clearly cutting back the revs now.

Would I be correct in thinking that if the new pulley fitted to the recon alternator is slightly too small it is obviously spinning faster and causing the alternator to produce an increased voltage? Or is it more likely to be a fault with the alternator?

Thanks
James
 

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It's a bad voltage regulator. It's inside the alternator but it's not worth buying a new one since you just put a reman on and that is causing the problem. A slightly faster or slower alternator shouldn't make any difference since the engine rpm goes up and down during driving too, the voltage regulator should keep it to normal levels.

Replace the alternator.
 

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Discussion Starter #9
Ok new alternator in and everything is running fine. A big thank you for everyone that helped. No doubt I will be on here again soon! All the best, James
 
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