Alternator Problem?

[Fastpedeller]

A couple of times recently my (old kit car, escort mk2 base) has had a problem with the charging light not extinguishing as it should..... I've had to rev it up to about 2000 RPM to get it to go out, then it's ok for the journey. It seems to be related to the ambient temperature as it's been ok when the temp got above freezing. I suspect a diode? but anyone expert on here offer any resolution (other than simple replacement or hoping for warm weather?)

[andyiley]

Sounds like the diode pack/regulator is on it's way out, a recon unit from your local auto electrical expert should sort out the problem.

Before you do, do you have/can you borrow a voltmeter?

If so when you next start it & suspect the problem may be evident do the following.

Start the car normally & check the voltage at the battery terminals with the alternator warning light on.

Then rev the engine to clear the light & do the same.

As a rule of thumb if you are getting 13.5 volts out the regulator is ok.

If you get significantly less when you first it & more when you rev it you have found the problem.

[Locknut]

By any chance have you changed the bulb in the warning light? It could be the wrong wattage.

[Fastpedeller]

Locknut said:

By any chance have you changed the bulb in the warning light? It could be the wrong wattage.

I've changed nothing in months (except the oil ). Strangely it was ok today (+5 deg C)I'm sure the ambient temp is a factor (albeit maybe minor one)

[T1pper]

Hi,
Have you checked the fan belt tension?

They can slip after a cold start, this is when the alternator is working it's hardest to replenish the battery.

It could also be worn/sticking brushes or as mentioned a fault in the reg/rec unit.

Prob best to source a replacement as these are quite an inexpensive unit, its better to deal with the fix as a routine repair than it letting you down on the road side

[Fastpedeller]

T1pper said:

Hi,
Have you checked the fan belt tension?

They can slip after a cold start, this is when the alternator is working it's hardest to replenish the battery.

It could also be worn/sticking brushes or as mentioned a fault in the reg/rec unit.

Prob best to source a replacement as these are quite an inexpensive unit, its better to deal with the fix as a routine repair than it letting you down on the road side

Good advice indeed - especially given the current weather. I may even have one in the garage - will have a dig around!

[GTIR]

A cheaper alternative is to find the part number and buy a voltage regulator on eBay. (Even if it's a genuine Bosch it's often cheaper than buying a recon unit)

Alternators very rarely "wear out" and it's often the regulator on 99% of instances

[Fastpedeller]

GTIR said:

A cheaper alternative is to find the part number and buy a voltage regulator on eBay. (Even if it's a genuine Bosch it's often cheaper than buying a recon unit)

Alternators very rarely "wear out" and it's often the regulator on 99% of instances

It's a Lucas - When I tried to get one apart years ago to get to the regulator parts it wouldn't yield. The Bosch one is a lot easier though as a couple of screws and it's replaced from the outside. I'll have a look at the weekend. Today it was lit again, but a good rev and it was ok for the rest of the day even though I stopped a couple of times.

[GTIR]

Then all you can do is pick a person you know and really dislike and kick them cleanly in the clackers/sponge.

I wish you good tidings.

[Fastpedeller]

Update...... Today no light when ignition switched on. I took the plug out and checked with the voltmeter, and there was 12+ volts to the plug. With the plug in and the engine running the volts at the battery was 12.24 (no change), so all-in-all a duff regulator or diode or both . Took alternator off (lots of rusty nuts and swearing), to find there is also some longitudinal play in the bearings!
A recon unit now ordered from local factor. Thanks to all for their advice.