Charging problem

[Kevin Garrod]

Just recently my ign light has started to glow dimly and erratically and the volt gauge shows between 11 and 12 with the engine running (confirmed with a volt meter)
It seems my alternator has packed up after only a few thousand miles.
Any advice on how to confirm this? Is it safe to un plug the alt and check the output?

[GDPR]

It needs a load to check output Kev - you may be lucky and have a high resistance in the fat brown wire, but to be honest it sounds like you have a dead or Last Rites alternator......

[PBH]

Check the obvious first is the fan belt tight enough and is the alternator pulley slipping as a result of a loose belt.

Peter

[Kevin Garrod]

So when I put the probe to the thick wire where it connects to the alt and get barely 12 volts, does that eliminate a wiring fault and confirm a duff alt?

[Kevin Garrod]

Done that Peter.

[PaterB]

Just finished replacing my alternator because of the same problem.

Simple check for alternator function: let the engine idle, switch on headlights and rev it up. The lights sould go brighter when revving up - if not www.midlandsportsandclassics.co.uk currently have new 18ACR alternators in stock for small money.

[jleyton]

Hi Kevin,

I'm no expert on the internals of alternators, however mine did the opposite of yours a few weeks ago and started overcharging - needle up in the15v+ sector and I double checked this with a multimeter.

Unlike you, at least I knew that the stator and rotor were doing their job, albeit a bit too well ! so I reckoned it could be just the voltage regulator.

Luckily a friendly owner gave me a crusty old alternator, but the VR seemed ok. With the alternator off the car it was a five minute job to swap over the Voltage Regulator and, upon refitting, SUCCESS .

Maybe that could be the same for you ?

Good luck.

Julian

Ps My alternator was only a few thousand miles old as well.

[Tdm]

Just finished replacing my alternator because of the same problem.
Simple check for alternator function: let the engine idle, switch on headlights and rev it up. The lights sould go brighter when revving up - if not www.midlandsportsandclassics.co.uk currently have new 18ACR alternators in stock for small money.

Mine had exactly same systems a couple of months ago, and had to buy a replacement Alternator from Paddocks.
The old Alternator was the original one though so had lasted 35 years.

[ChasR]

Just recently my ign light has started to glow dimly and erratically and the volt gauge shows between 11 and 12 with the engine running (confirmed with a volt meter)
It seems my alternator has packed up after only a few thousand miles.
Any advice on how to confirm this? Is it safe to un plug the alt and check the output?

What Russ said.

Where did you get the alternator from? I know of one owner who went through 3 alternators in a year before getting an alternator that worked correctly... I may have gone through a similar experience with a MkIV Escort XR3i many years ago. Pattern alternators would fail just after the warranty period (or just within). In the end a genuine alternator from a scrapper cured my dying alternator syndrome (but then again having an alternator in such close proximity to the exhaust manifold was always going to end in tears.

[V Mad]

Never run an alternator disconnected from the battery, as the voltage will go up out of control and can blow diodes or reg.

I ran a reconditioned alternator for a couple of years then it started to play up (internittently massive overcharge then normal ). I took off the plastic cover and found the electrical terminals were all loose. Tightened up and runs fine now.

[Kevin Garrod]

It's a QH alt from Paddocks, I might drop them an email and see what they say.