Alternator problem… again.

[element]

Seasons greetings...

Fiat Twin Cam 2.0 version 1983. I inherited the car from my dad, he built it 2001-2002. It sat under a cover for 8yrs then I got it running and have been maintaining it this last 5 years. Initially the alternator worked then it stopped working and I replaced it with one from eBay. 2 yrs later this ‘new’ alternator stopped charging the battery. I took this alternator last yr to an auto electrics specialist in Glasgow & they overhauled it and I refitted it and all was well again.. I have barely driven it 20 miles this year (what with the incumbent elephant) but that red light has come on again on the dash. Sure enough when I put my meter on the battery when its running; it’s not being charged. Yet if I leave it to cool down and try the next day start the engine, car stationary – it is charging… when it’s hot it stops charging.
So has anyone found a similar problem & if so how did they fix it? – Or shall I just replace it again for another one off eBay at £67?

[stevejgreen]

Re: Alternator problem… again.

Seasons greetings...

Fiat Twin Cam 2.0 version 1983. I inherited the car from my dad, he built it 2001-2002. It sat under a cover for 8yrs then I got it running and have been maintaining it this last 5 years. Initially the alternator worked then it stopped working and I replaced it with one from eBay. 2 yrs later this ‘new’ alternator stopped charging the battery. I took this alternator last yr to an auto electrics specialist in Glasgow & they overhauled it and I refitted it and all was well again.. I have barely driven it 20 miles this year (what with the incumbent elephant) but that red light has come on again on the dash. Sure enough when I put my meter on the battery when its running; it’s not being charged. Yet if I leave it to cool down and try the next day start the engine, car stationary – it is charging… when it’s hot it stops charging.
So has anyone found a similar problem & if so how did they fix it? – Or shall I just replace it again for another one off eBay at £67?

Is it a Lucas one. It could be diodes failing, a fairly easy diy fix.

[HairyDave]

Re: Alternator problem… again.

Contact the repairers and get them to fix it!

[andyf]

Re: Alternator problem… again.

Contact the repairers and get them to fix it!

+1

Also is it close to the exhaust manifold? It could be that a heat shield would help keep it cooler

[element]

Re: Alternator problem… again.

Gave it some thought and I wonder - if it works when cold but when the engine is hot it doesn't - could it be the belt is slipping when hot? I have had trouble with belts - there's not a lot of room and there's only one size /type I can use. I fit them when it's cold (obviously ) but maybe I can try tightening it while wearing gloves when it's hot and see if that fixes it... worth a try... I know nothing about diodes - or indeed what make the alternator is. However I have plenty to be getting on with... Timing belt change, exhaust removal , make new gasket and refit, handbrake cable replacement... Just as well there's a lockdown!

[HairyDave]

Re: Alternator problem… again.

Its a possibility, but unlikely, usually A loose belt squeals on starting when the alternator puts the power back in the battery. My suggestion is to ring the 'reconditioner' and tell them your problem. A decent company will ask for it back to check it over. Did you ask for it to be reconditioned or for a 'first aid repair' where they fix what is wrong and nothing else? Good luck and a Happy Hogmanay!

[Ye Ol Ripper]

Re: Alternator problem… again.

From memory the Fiat 132 2.0 had either a Magnetti Marelli or Bosch Alternator fitted.

If it's a Bosch, then you are in luck because it's an easy fix to change the brushes & rectifier back all in 1 go .

2 screws at the back of the alternator.

I have changed many of these Bosch brush/ diode packs with the alternator in situ after disconnecting the battery first in under 15 minutes . I haven't done so on a Fiat 132, which may involve removal of items to enable you to access the back of the alternator.

The following video explains the types on a Spider , however that Bosch type is internally regulated, so the part I have provided the link for is not compatible with the Bosch Spider alternator. So check what you have fitted.
https://www.youtube.com/watch?v=6jcxxK_6byE

So identify first the type of alternator. Provided the belt isn't slipping at cold start up , I would advise against over tightening the fan belt as that will cause accelerated wear on the bearings of the water pump and the front bearing of the alternator.

If it's a Bosch the part is most likely to be :
https://www.ebay.co.uk/itm/Fiat-124-...0AAOxyOMdS8TDO


As what you have is now in a Marlin , ensure also that the alternator is adequately earthed and that all of your wiring is intact .

I maybe wrong but seem to recall some Italian engines of that era had rubber mounting bushes in the alternator mounting brakets , and it was therefore reuired to have a separate braided earth wire to earth it to the engine block or head. It's been 30 years now since I worked on that engine though.

[d068795n]

Re: Alternator problem… again.

The diode pack is unlikely to be the fault, if a diode brakes down it does not repair itself depending on the underbody temperature. What you would get is a half wave rectification a mixture of AC/DC supply voltage to the battery. This would fry the battery which you do not say is happening. It is more likely to be the voltage sensor being affected by the temperature. This means that when it is cold it produces an output from the alternator providing the battery voltage is lower (it wont if it is not). And when the battery voltage is high, it cuts of the supply to the battery until the battery voltage is reduced. Then turns back on the output from the alternator. This also explains that when it is repaired and tested in a workshop the alternator is cold and their will be an output. I hope that this helps Stuart

[PaulW]

Re: Alternator problem… again.

Hi , Also suggest checking / cleaning Alt connections also Eth cable connections from engine block to chassis - there could simply be a high resistance connection which is breaking down when heat expands the metal.

Good luck and Best wishes to everyone for 2021 - better times are on the horizon !! Paul W

[element]

Re: Alternator problem… again.

The diode pack is unlikely to be the fault, if a diode brakes down it does not repair itself depending on the underbody temperature. What you would get is a half wave rectification a mixture of AC/DC supply voltage to the battery. This would fry the battery which you do not say is happening. It is more likely to be the voltage sensor being affected by the temperature. This means that when it is cold it produces an output from the alternator providing the battery voltage is lower (it wont if it is not). And when the battery voltage is high, it cuts of the supply to the battery until the battery voltage is reduced. Then turns back on the output from the alternator. This also explains that when it is repaired and tested in a workshop the alternator is cold and there will be an output. I hope that this helps Stuart

This sounds likely - where would I find the voltage sensor? - I imagine it isn't part of the alternator itself; if it is part of the charging circuit - I can maybe find it if I trace around the engine bay & hunt for it - if I knew what it looked like - presumably it is from the original donor Fiat Argenta?
The alternator is earthed with a braided strap; it looks ok.

When the repairer 'repaired' it - they also replaced the pulley, I believe they are a good business. Trouble is they are in Glasgow and it's an awkward haul to get there and back and then go back another day to collect it... Given the history of the problem - I surmise the fault doesn't lie with the alternator itself - I have had cars with no alternator problems over 10yrs+ yet this is a repeat of a repeat...

[dogoncrazy]

Re: Alternator problem… again.

My Alfa engined Roadster had a separate/remote voltage regulator despite if I remember it being a Bosch alternator. It looked like a slightly bigger version of the voltage stabiliser they use on Smiths instruments such as fuel and temp gauges. It's a sealed unit so non adjustable.

[d068795n]

Re: Alternator problem… again.

I only have information for these alternators. Lucas 15AC these have seperate alternator control unit. These are a square box having three lucar connections a space then another all on the same side, this is marked 4TR or another rectangular box marked 8TR with the terminals in the same position. These are interchangeable.
Lucas 15 and 17ACR Alternators, in these machines the control unit is built into the alternator, Resistors R1 and R2 are used for battery voltage sensing. Delco Remy Type DN460 Resistor R2, R3 and a Thermister causes voltage to vary with temperature. Again this control unit is built into the
alternator. I think it follows that when having an alternator repaired ask the mechanic to check it out at as near to running temperature as possible. I hope this helps Stuart

[HairyDave]

Re: Alternator problem… again.

First ring the reconditioner and ask them to sort it. If they won't help tell them that you intend to get someone else to fix it and you expect to recover the money from them. This may well be the cheaper option. I would be surprised if Dundee did not have a decent Auto electrician.

[element]

Re: Alternator problem… again.

First ring the reconditioner and ask them to sort it. If they won't help tell them that you intend to get someone else to fix it and you expect to recover the money from them. This may well be the cheaper option. I would be surprised if Dundee did not have a decent Auto electrician.

Not only are the repairers a 90 min drive from me; I removed it from the car & took it to them; they couldn't (and can't) test it in the car; only on a workbench. They did replace some parts in it that they had to order but I didn't ask what these parts were. Once I got it back and refitted it - it was working fine in the car. Only last year post-primary lockdown did the problem reoccur. I doubt that the alternator itself is faulty and that the problem lies in the car elsewhere.

Yes there are auto electricians evrywhere - I can visit one in Perth in 20 minutes; but atm that is impossible, the new current lockdown prohibits this plus the car is SORN. I have to resolve this myself.

[duncan]

Re: Alternator problem… again.

Hi - you are stuck with a non operational car and the lockdown

I would suggest that you buy a multimeter - if you haven't already got one - and bodge yourself an alternator test setup

I'm thinking your electric drill or other motor driving the alternator - the loads will be low so you can just gaffer tape them together

The idea would be to test the alternator on the bench - and then on the car using the drill to drive it while you did the checking with the multimeter