18 replies to this topic

[Dusky]

Okay, so a new belt didnt sort it...
My voltmeter (connected to startermotor + and an earthing point) reads 12.5 volts when the engine is off.
With the engine running I read anything between 12-13.5 volts (very shaky needle).

Took out the multimeter and measured between the + on the alternator and the casing, got readings between 6 and 35 volts... Jumping between these readings.

On the battery itself I read (while running) between 14.5 and 35 volts.
Am I right that this is a voltage stabilizer problem? or would my voltage gauge be faulty , causing bad readings?

But why would the ignition light come on then?

Edited by Dusky, 20 September 2014 - 10:30 AM.

[Ethel]

It does sound like a regulator fault. Just put your meter across a known voltage, like a few new Duracells if you doubt its accuracy.

 

Voltage isn't an absolute, it's also called potential difference - the meter shows the difference between the 2 probes, 12 on the +ve & 3 at the -ve will read as 6 volts.

 

The ignition light is similar, it goes out when there's about the same voltage on either side of it. If there's 12v on the battery side and the alternator is pumping out 30 odd volts it'll light (brightly!). This is clever as it can tell you more:

 

A light that dims as you rev the engine shows the ignition is taking more from the battery than it can keep up with i.e. it's not been charged.

 

A light that's brighter is showing increased voltage from a faster turning alternator i.e. the regulator isn't regulating the alternator.

[Dusky]

It does sound like a regulator fault. Just put your meter across a known voltage, like a few new Duracells if you doubt its accuracy.

 

Voltage isn't an absolute, it's also called potential difference - the meter shows the difference between the 2 probes, 12 on the +ve & 3 at the -ve will read as 6 volts.

 

The ignition light is similar, it goes out when there's about the same voltage on either side of it. If there's 12v on the battery side and the alternator is pumping out 30 odd volts it'll light (brightly!). This is clever as it can tell you more:

 

A light that dims as you rev the engine shows the ignition is taking more from the battery than it can keep up with i.e. it's not been charged.

 

A light that's brighter is showing increased voltage from a faster turning alternator i.e. the regulator isn't regulating the alternator.

Its getting very strange now  

Because I was driving with it yesterday, with the ignition light very on, but very dim, but sometimes it was very bright, so Im getting more confident that it is the regulator switchign between all thsoe voltages?

 

Can you break a alternator by driving with too much revs all the time? ( sees lots of 5-6K rpm )?

[Ethel]

Not really,  but it will wear out quicker just because it's turning more times per mile and it will generate more heat that it'll need to dump. You could get some hp back with a bigger pulley on it.

[Ruckus]

STOP

If you battery is getting 35volts it's will kill it or worst make it vent and spray acid everywhere.

Worst case it could explode. No joke.

Get the alt off and take it an auto electrician or Alt/battery type place ASAP.

[Dusky]

I did stop directly ( well 2 minutes) after seeing that high voltage

Do you think they can fix a voltage regulator?

Or should I just buy a new one to be sure? ( any differance between a 55 and a 70 amp in terms of bhp the engine needs to power the alternator?)

[Ethel]

They could, but it's probably not cost effective. Yes, more power out means more power in, but only if you really are drawing more power.

[Dusky]

They could, but it's probably not cost effective. Yes, more power out means more power in, but only if you really are drawing more power.

So basically no more power draw when im driving without lights etc et?

 

I think it'll be a new alternator then... unless someone like kernowcooper knows a better solution?

Edited by Dusky, 20 September 2014 - 12:09 PM.

[silve1999]

You can replace just the regulator just 3 bolts but soak them in release fluid as they shear easy and round off easy too ;) new regulator are about a tenner with new bushes on too may be worth a try before shelling out for a new alternator?

[Ruckus]

Local place near me in kent, just does an exchange. I think it's like 35 or 40 quid.

You get a 100% refurbed unit.

[sledgehammer]

You can get refurb kit like this - (not saying this is correct for your car) -

 

may be cheaper / better to buy recon / new

 

http://www.ebay.co.u...=item2a25ef3d20

 

used to do loads when I was an apprentice , then the alternators got cheaper

 

and as above - battery can get hot / boil off the acid when over charging & be a fire hazard

 

this can also cause rust in unusual places 

[Dusky]

Found a weard thing.. Seems my alternator is not a lucas one but a Magneti Marelli one... MAybe because its a european car?

[Ethel]

Possibly, I know the Ducellier dizzies were part of a deal to use locally produced parts on the Belgian assembled Mins.

[Dusky]

Yeah, propably

I've been browsing through my dad's ritmo(strada) alternators, and the castings are the same. But the internals are a bit different ( different connections)

I saw a new alternator here in Belgium for sale so I hope it's still for sale, then I'll buy that one

Otherwise I'll just buy a minispares one

[HarrysMini]

Found a weard thing.. Seems my alternator is not a lucas one but a Magneti Marelli one... MAybe because its a european car?

I know Magneti Marelli supply parts for Italian cars, as my alternator in my Fiat is also made by them.