D1 alternator burn

Got my 97 jap auto D1 (with EDC) running,finally,thanks to all who posted help. Have been running the engine,vehicle parked,for 30-60 mins a time all day to check for leaks etc.Just when I thought all was good...

....smoke pours out of alternator.So I turned it off.

Earlier on I measured 14.4v charge,all good.But just now I switched on the aircon and in a couple of mins I noticed a little water on the battery ( I had filled it a little generously so thought nothing of it)........then the revs increased a little for a minute,then down again,....then smoke from the alternator.

I didnt have time to check what it was putting out at that point as I was more concerned with,well,putting it out.

So........why?What?How? If I fit another alternator,wil this happen again ? And what about the battery ?

Nobody ?

if the water has come out the battery it aint water its acid...... the acid only needs to just cover the plates on a cold battery...... as its charged the fluid expands and the level rises..... if youve over filled with water it can overflow. if its too full you can take some fluid out with a pippette, (tube with a squeezy rubber ball on top), or soak some up with a bit of tea towel, but be careful its sulfuric acid.... have a bucket of water handy to pour on any spills etc...... it will eat through your body work (you and the car) if left


the smoke is most likely an alternator fault
id fit a used alternator and see what happens

Ricc,thanks for the reply....yes ,I do realise that the fluid is acid, I should have been more succinct ! I only mentioned that because it was a possible link in the chain of events,ie, that batteries can boil up when an alternator starts to overcharge.
It was a VERY small amount of water,a couple of cc's at most but when describing a problem it is best to give all possible info.

However ,I am no closer to getting any answers on whats going on. It was NOT the alternator that came with the vehicle (which was labelled GM) that was a Magnetti Marelli of the denso design of the lucas A127 type......if that makes any sense !

The alternator that had been fitted had been liberally flooded with water and antifreeze on two headgasket failures. So, I fitted the 100amp alt. of the same design that I had on the shelf which was very nearly new but for sitting unused for 18 months.Prior to fitting I had flooded it with switch cleaner and air-line blown it clean and left it to dry.For a long time.It has been sitting on thatr car for about 3 months,unused, awaiting head repair.

The alt. was fine, running for long periods until I put the aircon and fan on, at tickover.
Then revs went up,down,up then smoke from back of alternator.Ignition then turned off,battery disconnected.

Granted,this was an old battery but it was fully charged and was holding 12.6 volts and was man enough to start the car.

Could a battery fault cause the alt to burn out under load ? Why would and alt. burn out under load ? And what is it that will have burned ? I dont have the unti here with me to inspect or describe.

I have the one that was watered....is it worth stripping it and cleaning and then using ? Should I source a repair pack for it ? What is it that will need to be replaced ? Do I need to replace the battery at the same time,given that it still gives good numbers on the meter ?

I HAD wanted to get this one into MOT today,but THATS not happening now !

Any advice,opinions,experience gladly received, however basic....you dont got to be an expert....just tell me what you did in similar circumstances.

Come on guys,give us a hand....please ! Its easy to diagnose faults in other people motors as you can be detached and calm, but when its ones own,one loses perspective !

Sorry to doubt your observations but are you SURE the smoke was from the alternator and not just being sucked past it?
The A/C being switched on might be a red herring or it might have caused the A/C unit to seize and the belt to heat up/burn.
I reckon you are going to have to fire her up again, perhaps with the fan removed, so you can see what is happening & where.
Whillst running check the voltage and then put the lights on to load the Alternator & see if it smokes again (A/C wouldnt overly load alt'r unless on max at the blower).
Oh, and have an extinguisher at hand!

shocker said:

Prior to fitting I had flooded it with switch cleaner and air-line blown it clean and left it to dry.For a long time.It has been sitting on thatr car for about 3 months,unused, awaiting head repair.

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Sounds like that might be the problem, the contact cleaner could easily have 'cleaned' the bearings dry too .. especially as you blew it then left it to dry. When you switched in the higher loads the bearings couldn't cope and burnt out.

Thanks Paul,

No noise......would the bearings have heated sufficiently to melt local plastics ? Arent they sealed bearings ?

if youve got the alternator off it will be obvious if the bearings have gone... it should spin easily by hand with no noise or roughness.

the air con compressor is belt driven ... the only significant electrical load will be from any fans.... but that shouldnt be enough to burn oot the alternator.... im not familiar with the aircon set up the belt was off the compressor when i bought mine....ive never bothered refitting it.

Ricc...I am not convinced that the aircon would cause the bearings to fail, I am just listing the series of events . The vehicle is at another location and I dont have the offending alternator with me.

One thing that occurs to me....could the poor earth from the engine to the chassis have caused the alternator to fail and melt down ? As in,you dont run the engine (and hence alt.) with the battery disconnected as this will shag the alt.....so if there was a temporary failiure of the earth and so in effect,a disconnected battery, would this be the result ?

I did at one point have the extra earth lead from the battery to the aircon mounts disconnected whilst the engine was running......and was thus relying on the suspect braid from the starter to the chassis. Note,please,that the main earth lead was not disconnected from the battery at any time ! Im not QUITE that stupid !

when you replaced the alternator did you use the same sized pulley and connect it the same way not teaching you to suck egg just enquiring. for the battery to boil is usually a sign the slip rings or brushes are worn the tell tail sign is the voltage to flair up and you would have very bright light when revving

Same size pulley,didnt rev - was just letting the engine idle to run in the head, didnt check voltage at time of burn....

....thats a bloody useless answer innit? Thanks for the reply,mystery,didnt know that about slip rings and brushes,thought that was rectifier going home that did that !

ricc said:

if youve got the alternator off it will be obvious if the bearings have gone... it should spin easily by hand with no noise or roughness.

the air con compressor is belt driven ... the only significant electrical load will be from any fans.... but that shouldnt be enough to burn oot the alternator.... im not familiar with the aircon set up the belt was off the compressor when i bought mine....ive never bothered refitting it.

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Yes,Ricc, that is why I am confused....other than the electric clutch the air con should only present a mechanical load , the fans had been on for some time.

Unless anyone has any advice for me all I can see ahead is to put a spare unit on after a good check over and order a re build kit for the first one.I have a 65a lucas unit on the shelf but dont think it suitable for a vehicle with a lot of electrical kit plus tow and split charge current draw.

The pulleys on my alternators are all the same size as my discos fall into the same age group.

any alternater that fits will do to check things out..... if yer doing a lot of stopping and starting with a lot of eletrics on it may not charge the battery fully .... and youll end up not bein able to start on a cold morning

Thanks Ricc, I am off soon to look at the beast,taking the spare marelli 100a unit and now,since you said that,the lucas lower powered one,too.

Lots of people advertise repair kits on e bay and say that they will fit marelli units - when questioned about visible differences they admit they will NOT fit.Those kits go 20 quid-ish.The only people who have the correct full kit with bearings want £78 +vat+p&p.....I was offered a 120amp unit,new for 90,delivered yesterday ! Quelle damage !

Put another , identical, marelli 63340004 high output alternator on the vehicle , same battery....no problems. Drove the car around,put lots of electrics on ,though not the aircon,(!) and all seems fine.So far.

The unit that came off : had the plastic back cover off for a quick look and cant see any obvious signs of any burnmarks , the brushes and ring look OK. However,the front bearing is squeaking with just hand spinning so I would think that it would not be happy at speed. Have been quoted £25 +,+,+ for bearings but since most alts. use washing machine bearings I will source one elsewhere.

Thats as far as it goes for now !