OK I need some help here. About eight months ago I had an alternator go out. I replaced it and about two months later i had a bearing go out on the alternator so I replaced it again, about two weeks after that I had a diode go out on alternator so I replaced it again, About 2 months later I had the diodes in the alternator go out again and replaced it, Here last week my lighting light was dim and when I push the accelerator the light would get brighter so I pulled the alternator and went to exchange it again they said it was fine. I put it back in car same lighting bolt light issues. I took the car to the parts store where I had the alternator tested and the test came up a diode but when I took the alternator back out for the exchange they tested it again and said it was fine. As you can imagine I wasnt very happy and made they exchange it anyway because I have to wait ten days everytime I have to exchange. Well I put in the new alternator and no lighting bolt light and car charging fine. SO I GUESS MY QUESTION IS. Could it be something on the car causing these issues or am I just having really really bad alternator luck. What could i try or do or have checked out.

 

do yourself a favor and switch to a GM alternator. i had an alternator go bad. wouldnt charge above 3k rpm. autozones tester obviously doesnt spin it that fast and they wouldnt replace it. i was pissed. and the manager who wouldnt replace it was my boss, so i was doubly pissed.

 

When I switched my engine I didn't even bother with the Lucas alternator, I put in a GM. No problems with the Prince of darkness now!

 

I believe it is a gm alternator when I did the last one here they told me this is the last one and next time we are giving you your money back or you can pay 100 more for the one for European cars

 

I have a pal with an older XJ6 who went thru virtually the same scenario. The end of the story was that the output wire had excessive resistance. Replacing it solved the problem once and for all.

In your case I think the output wire goes to the main starter terminal so it'll be a little tricky to reach...even to put a test meter on it.

That said, the quality of rebuilt alternators is very iffy. On various occasions I've had to go back for multiple exchanges.....that's the reason I've started using a local rebuilder instead of buying over-the-counter. I've had much better results.

The Prince of Darkness stuff isn't relevent here. The Lucas alternators are a perfectly satisfactory design....most originals last 20+ years. Once anything has been rebuilt the focus then falls on the rebuilder.

Cheers
DD

 

My 1985 absolutely ate alternators, at least one every 18 months for years. In the end this is what I did:

1: The standard 75 amp alternator is not up to the job, whatever anyone says to the contrary
2: I fitted a 115 amp unit from the later cars, swapping out the serpentine belt type pully for a normal V pulley
3: Replaced large wire from alternator to starter and cleaned up starter terminal AND terminal post on the firewall. The charge goes to the firewall via the starter so this is important too.
4: Added extra earth from alternator body to engine AND replaced standard earth from engine LHS to chassis frame LHS that goes via front subframe LHS, and cleaned up all fixings involved so earths absolutely 100%.

Grant Francis advised me on all this and he is 100% correct.

Result is that the charging has never been better, gauge at top of charge section, 14.5 volts on my cigar lighter socket plug-in thingy, so far no problems at all.

Greg

 

I too had the exact same scenario as you. My original alternator finally gave up after about 20 yrs. I was excited to find AutoZone had a "rebuilt" for a good price. Installed that. Two month later it stopped working and I barely made it home. Lifetime warranty so they gave me another and I installed it along with a new wire from the output terminal to the starter. That one lasted about a week. I took it back and they gave yet another. I got maybe 2 months out of that one and the lightning bolt came on. Now I go and demand my money back which I get. I kept my original alternator so off to the rebuilder I go. I have known him for 25 yrs. He says don't waste my time. The parts he can get for it are cheap junk and he won't use them. I would have to hunt down original Lucas parts.

I ended up using the bracket kit from John's cars. I bought an alternator from my rebuilder friend and it has been good for 7 yrs now. BTW the original is 75 amp and is not really large enough. Just barely effective when driving. At idle it will discharge the battery. The replacement unit is a 94 amp GM model. Vintage 1980s. John's kit is a bracket that bolts right in. Then the GM alt goes in the stock location. John will sell you a new not rebuilt alternator fairly reasonable. The model is a 12Si. The main differences are the clock position of the connector. Easily changed but if you are nervous about that then buy the correct clock position. Mine has parts in it good for 140 amps so hopefully will last a long time.

With my original Lucas when I had A/C or defrost, wipers and headlamps on it would start to discharge the battery unless the RPMs were about 3000 or so. With my current setup this is not the case.

If you read Kirby's book you will see some have installed the CS130 where the air pump is or was. There is a Marelli model that bolts right in. Personally I like the GM unit since parts are available pretty much anywhere.

 

Heh heh, we all form conclcusions from our personal experiences and I'll always defend Lucas from gratuitous villification :-).

It's true that Jaguar should've specified higher output alternators. I'm sure that Lucas would've gladly obliged. I myself experienced this weakness with my XJS and Ser III XJ6 if, at idle speed, the full compliment of high-load equipment was used simultaneously: rear defogger, highest blower speed, wipers, and headlights. A higher output alternator of any design....Delco, Motorola, Marelli, Lucas, Bosch, whoever....takes care of that issue.

My own experience with Delco alternators has not been favorable. I've owned scores of GM cars, several of which have required multiple alternator replacements or overhauls. The most glaring example, of several, was the '94 Suburban that ate 5 alternators in 200k miles. Following the usual pattern the original lasted the longest...about 80k miles, I recall, and then a sucession of rebuilt units..."AC Delco" branded. Nowadays we know that the label on the box simply doesn't ensure high quality or long life.

I might add that I spent 30+ years working in GM dealership parts and service departments and I can positively assure you that alternator replacements were commonplace. Besides electrical failures there were overheating and bearing failure issues for many years, especially in the 90s. Nowadays improved bearings and fans are out there to solve some of those issues.

In fairness there are many, many cases where Delco alternators have lived to a ripe old age with nary a problem. Another advantage of the Delco units is easy availability of repair parts for DIY overhaul and upgrade parts for improved performance and reliability.

Also in fairness I'll add that I've worked on many old Jags, including my own, with 15-18-20 year old Lucas alternators still working perfectly well. Same for Lucas starters, as well. I'm not aware of any design flaws in them that contribute to poor reliabilty or durabilty. The problems seem to begin when they are rebuilt to sub-par standards by the same high-volume remanufacturing facilities that bollix up units, of any brand name, on a regualr basis :-)

The local rebuilder I use doesn't seem to have any issues...other than waiting a couple days... with repair parts for Lucas units. Or at least never reported them to me.

In the end there are some legitimate and practical reasons to to replace the Lucas with something else. Just don't expect a 100% guarantee of bullet proof performance because it's an AC Delco design.

OK, I'm off my soapbox :-)

Cheers
DD

 

you have to buy OEM GM if you want it to last. that rebuilt junk you get from the autparts store is trash. you would be better off buying a used factory alternator from a junkyard, than autozones crap. i had a bad duralast out of the box and my manager wouldnt replace it.

 

Doug,

Believe me I am not looking at the GM alternator as a bullet proof replacement. I switched because I was struggling to get a good rebuilt or parts to rebuild my original. I was driving around with a fully charged jump box in my trunk just in case I had a failure. I went with the 12si alternator because they are pretty reliable and parts are readily available pretty much anywhere. So if I had an issue away from home I have a chance of fixing it.

I did not go with the CS130 alternators that GM used in the 90s. I had my own dealership, not GM, at that point and saw so many failing from bad bearings. I had customers coming to me because they had multiple failures and wanted a second independent opinion. I think this is why GM made a model with a heat sensor that basically shut down the alternator if it got too hot. Also the little rear bearing used to go bad all the time. Now there have been improvements made and those problems are mostly history. Seems GM has a history of making something and it not working out too good at first. I remember their first power rack and pinions had issues in the morning. Automatic transmissions/transaxles had a similar evolution. Although they never did recover from the whole diesel engine mess. That killed a whole market segment until recently.

I would have preferred to use a Bosch unit but I could not justify the price to switch over. I think the key to a long lasting alternator is to go oversize so that the electronics in it never really get too hot.