Help! Calibra alternators being killed

[Manbearpig]

Stepson has a Calibra 8V, was my FILs before him and mine before that! Something of an heirloom. But it has an incurable charging problem

 

Symptoms start typically when there is a monsoon; lights on, wipers on, fan demisting, etc all heavy load. Car has a voltmeter on which has proved to be as accurate as any external gauge applied. Voltage runs under 12V a lot of of the time then under full load more like 11V. If the monsoon keeps up long the car dies

 

In the past few years it has gone through alternators very rapidly, last new one lasted 20k and a year, the one before that maybe another year, one before that maybe 2. I just can't believe these are the root cause, and surely can't get 3 duffers in a row.Problem must lie somewhere else, mechanics all say "not charging mate" and on goes another.

 

Last one was an Ebay special, so just today FILs garage chum dug out a 2nd hand but good original Calbra alternator he'd had lying around for ages and on it went. Started it up, indicating 14V, 11 miles later at home dropped to just under 12V, tried loading the car up with all the usual including heated seats. Tried the wipers on fastest setting and they were nearly crawling

 

What can be wrong? Some loading somewhere? It does have broken aircon which is a bit of a unknown quantity, but as far as I know the pump is not dragging it down, car feels sprightly on 105k miles

 

Any clues?

 

[mat_the_cat]

First of all, where is the voltmeter measuring voltage? If that's true battery voltage then you have a problem from the word go. If not then you have a voltage drop between the battery and wherever the meter is wired in, which isn't surprising but not very useful.

 

It sounds possible there is some abnormal loading somewhere, so an ammeter might be useful to confirm or disprove. I've just had a failure of a brand new pattern alternator after only 21k miles, so it seem like there are some poor quality units out there. My brushes were well worn, but I managed to stretch the springs to gain a little more life.

[Barry Cade]

Older Vauxhall alternators were mounted on rubber bushes, and had a separate earth strap from the bracket to the alternator- is it still there? Usually earthing faults IME.

 

 

[the judge]

How many batteries? Dead cell? And check this^^^ asap

[twosmoke300]

Deffo check the earth strap. And drop an amp clamp over the battery lead when it's running . I had a focus that the battery was pulling 80a from the alternator even though it was fully charged. Burnt it right out.

[Richard]

A quick fix for the earth strap is to clip a jump lead between the alternator and engine.

[Cavcraft]

I'd be looking at the earth strap too.

[twosmoke300]

And maybe change "mechanics" if it is that and they havent noticed it

[Asimo]

Alternator Earth Strap.

Sometimes these get fitted by mistake to one of the bolts that pass through the centre of the rubber bushing so that they are electrically doing nothing.

 

With Engine running and lots of electrical load on, headlamps, de-mister etc, measure the voltage between the alternator body and engine block: should be zero.

[Manbearpig]

Earth straps? Must admit I've never noticed one, will have to Google where it's supposed to be!! On other car ben obvious between gearbox and chassis but not here.

 

Chatter on the forums indicates that only early cars had earth straps to the alternator, but others have added their own

 

Just had a look at this 2nd hand alternator that father in law's mate fitted gratis, and it's 55A which seems really small.

 

Yes batteries get killed off as well, FIL fitted a new battery this time as well, and it got flattened. I could only get a half charge on it overnight - must have been dead as a dodo.

[Mr_Bo11ox]

If you're not sure about the earth strap just get another one and bosh it on somewhere 'twixt engine & body, can't do any harm

[twosmoke300]

It's a separate lead just for the alternator. As mentioned before , fire it up with multimeter across the battery . Then connect a jump lead between the alloy body of the alternator to battery earth. If the voltage across the battery jumps up then that's your problem.

[Manbearpig]

Thanks all, that's couple of jobs for the weekend.

[Manbearpig]

It's a separate lead just for the alternator. As mentioned before , fire it up with multimeter across the battery . Then connect a jump lead between the alloy body of the alternator to battery earth. If the voltage across the battery jumps up then that's your problem.

 

Checked the Haynes in detail, the early alternators had their own earth strap (there's even a picture so even I can't miss it!), these were the pivot mounted alternators that tensioned the belts. This car has the later "compact delco remy" as described in the manual, bolted directly to the block and a seperate tensioner, so no earth strap.

 

No sign of  the engine earth strap is, need a good look and fit one as advised

[Barry Cade]

Guy at work is Calibra daft- he's had his 8v turbo converted SE5 for 9 years, and has broken another 4 over the years for parts. He's got a huge stash of parts!

[Barry Cade]

Deffo check the earth strap. And drop an amp clamp over the battery lead when it's running . I had a focus that the battery was pulling 80a from the alternator even though it was fully charged. Burnt it right out.

That will be one of those smart charge jobbies- I've got the scars on my hands to show what happens to these when they go Pete Tong- dead short, glowing wiring and a flat battery in seconds....if you are lucky/

[Manbearpig]

This was solved a while back and I neglected to explain how as part payback for advice from everyone

 

Turned out it was the eyelet on the cable attached at the back of the alternator. Corrosion had built up between the copper core and crimped part of the eyelet to such an extent that it could not be pulled off, but on acceleration (when the engine rocked) it lost contact, hence stepsons claim that the lights died on joining the motorway. The eyelet came off with a reasonable tap from a hammer, exposed some fresh core and crimped a new eyelet and away it went!

To think that at least 4 alternators have been binned because of this and at least 2 mechanics never noticed. Hope this may help someone's diagnosis in future, a visual check may not be enough, waggle away and use a voltmeter across each cable!