Another broken dynamo?

MartinP · Post by **MartinP** » Mon May 14, 2007 8:08 pm

A few weeks ago the charging light on my 67 912 started flickering gently, then all of a sudden came on strong. There was no reading from the dynamo and so I took it to see Andy Prill who fitted a new one.

This morning, the light started flicking dimly again, then this evening while storming along the motorway, the light came on brightly. So, does this mean I've got another knackered dynamo? Is something else causing them to go?

Oddly, when I went to see Andy the first time, he told me that if he polarised the dynamo and it span like a motor, that it was fine. He did that and it span but when he took a reading across the dynamo it showed no output. Does this mean that potentially his first diagnosis was not as straightforward as we both thought? Despite the charging light going straight out as soon as a new dynamo was fitted? Or have I just had a spot of bad luck and the new dynamo is substandard?

Any thoughts would be gratefully recieved!

912uk · Post by **912uk** » Mon May 14, 2007 10:15 pm

just to confirm which light on the dash are you talking about.

Ian Gunney · Post by **Ian Gunney** » Tue May 15, 2007 7:23 am

have you checked the belt tightness?

I had a similar experience to you Martin with a recon dynamo from another parts supplier - once that was exchanged, touch wood I've had no problems since.

I'm sure that Mr Prill will be able to sort it

MartinP · Post by **MartinP** » Tue May 15, 2007 7:36 am

The light is the red ignition light on the left hand side of the oil temperature gauge. The light came on at exactly the same point in the journey that it happened last time: trundling along in slow motorway traffic for five minutes or so, then the traffic clears, I push ahead to motorway speeds in the outside lane and then the light suddenly comes on and stays on.

The belt tension is okay - can twist it a quarter of a turn and no more, plus all the pulley parts are tightened up.

Is there any chance that it could be something to do with the battery? Or if it was the voltage regulator, surely the charging light wouldn't have gone out as soon as Andy fitted another dynamo?

912uk · Post by **912uk** » Tue May 15, 2007 9:03 am

That's the thing Andy does know his stuff.

I would just check some basics first

The battery as Ian said, Before start up what voltage and then while running and later when stopped. See if there is any change ( there will be that's what your looking for )

Clean the contacts up with some sand paper.. on any old car it's worth doing this.. I corrected so many problems with this method over the years..

Failing all that it does sound like rotten luck and you may have a problem and need to go back to Andy and get another unit..

My light flickers alot ( mainly round bends ) but always goes out.. and then when I stop the car it flickers.

MartinP · Post by **MartinP** » Tue May 15, 2007 9:06 am

Tested the voltage at the battery - 12.3 at idle and doesn't rise with revs. At the dynamo, there is no reading (or something like 0.03). This doesn't rise with revs. Upon closer inspection, there appears to be a burnt out wire inside. Andy reckons that perhaps the regulator is at fault and therefore has caused the problem in the dynamo.

912uk · Post by **912uk** » Tue May 15, 2007 10:04 am

rotten luck..

Well you know what the problem is now so should be an easy fit I guess. Can't the wire be repaired and then change the reg..

MartinP · Post by **MartinP** » Tue May 15, 2007 10:07 am

Perhaps. That was just Andy's thoughts over the phone by the way - I'm hopefully going to take the car to him on monday so that he can asses it in the workshop and then change what needs to be changed.

912uk · Post by **912uk** » Tue May 15, 2007 10:14 am

oh dear god I am starting to sound like Andy....

Well I think he had the school of " every ones thick on these cars until you prove other wise" . I am leaning these cars and I am deturmind to do so.. Our last chat was one of interest where we had a very good chat about anumber of things related to the US way and the UK way. I have learnt alot from him but also I have learnt alot for my self. So it's a case of putting togeather to good from the BS that's out there.

Tell Andy I will be coming up after the Scotland trip and I will want him to do my Heads as per our phone call the other week and I will drop the heads off and collect the crank at the same time.
Also tell him you win I have an SX1 cam now..

revival-cars · Post by **revival-cars** » Tue May 15, 2007 11:59 am

In my experience the finger can usually be pointed firmly at the regulator for most 912 charging issues - Part of the reason why I've just bought myself an alternator for my car!

MartinP · Post by **MartinP** » Tue May 15, 2007 12:00 pm

Thanks Max - hopefully I'll get it sorted next week but for now it's back to charging the battery between trips! By the way - calipers should be here today! Fingers crossed...

rafiki · Post by **rafiki** » Tue May 15, 2007 3:43 pm

revival-cars wrote:In my experience the finger can usually be pointed firmly at the regulator for most 912 charging issues - Part of the reason why I've just bought myself an alternator for my car!

I was under the impression that one cannot fit an alternator to the 912 engine. I'd be interested to know if this is indeed true.

912uk · Post by **912uk** » Tue May 15, 2007 3:49 pm

yes you can there is some kit available in the US.. I forget who it was selling it..

MartinP · Post by **MartinP** » Tue May 15, 2007 3:51 pm

http://store.emorymotorsports.com/35alki.html

912uk · Post by **912uk** » Tue May 15, 2007 4:04 pm

Gary Emory that was it...I think he developed it for his racing cars..