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944 Alternator issue .... help needed


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Hey All,

Having an odd issue with the alternator on a 1986 944 ...

It started with the alternator stopping to charge the battery. Through a series of Google information and sites, I changed the voltage regulator and got the alternator charging again ... (YAY me!!).

I now have the little red light on with the ignition on and the gauge shows charge when the car is started.

The problem I'm having is  as follows ... I'm getting a squeal from the engine bay, both at idle and under revs .... it doesn't last very long but while it is squealing, the voltage drops down to 12v showing no charge from the alternator ... when the squeal stops, the gauge goes back up to 13v so I know it is operating again. It can happen within the space of 5 minutes but doesn't go for very long.

The belt is fine as is the wiring ....

The big questions for those of you in the know are .... have I somehow put the regulator in wrong?? Is it normal for new contacts on the regulator to need wearing in?? Have I put the cover on the rear of the alternator on wrong?? I've read that there is some sort of fan on the rear of the alternator ... is something intermittently blocking it making the squeal??

I welcome any suggestions and remedies but please be gentle with me ... any technical answers will be met with a blank look ...

Thanks in advance ..... :)

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.......spinning slower causing voltage drop.......?


Thanks mate .... I'm going to have a proper listen to it tomorrow ... I was hoping someone had experienced the same thing and could pinpoint it straight away


Sounding like a bearing to me. You're going to have to go back in. 

I'm preparing to do just that .... although I changed the regulator without removing the alternator from the car.

It just annoys me that before the new regulator, it was working fine with no issues or noises ... I'm convinced it has something to do with the new part ....

Thanks for your input ....

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Is it a V belt or toothed? Sounds very much like a slipping belt to me which would cause it to spin slower.

Not quite sure on the belt but I don't think it is toothed ....

Will explore it a bit further but what you have suggested sounds like a possibility ...

Cheers .....

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Adam is probably on the money here. The 944 runs a 6pk by 1000 belt, they need to be tight. Unusually tight actually. On start up you draw quite a bit of current and the battery is put under strain, The alternator sees the drop and tries to charge at a significant rate, this makes the alternator hard to turn and the belt will slip causing the noise you are hearing. tighten the belt and try is again. 



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