Thread: Alternator problem

Originally Posted by steveG

I've got a 120A unit- one of these: 12V 120Amp Isuzu N Series Holden Rodeo Jackaroo Diesel Vacuum Pump Alternator | eBay Seems very well made compared to one like you originally posted the link for that I got from the US. If you're happy with 70A, check the dimensions on this one - 5 year local warranty and at a quick glance may well be a drop in replacement: Holden Jackaroo Rodeo 4JA1 4JB1 Diesel Alternator | eBay Steve

Thanks heaps Steve.

I have a dumb question. If it's just diodes that are dead, can they not be replaced for a few dollars?

Originally Posted by Judo

I have a dumb question. If it's just diodes that are dead, can they not be replaced for a few dollars?

yep, bout 3 bucks a piece plus labour last time I did one.

and if you have 2 dead alternators, know how to drive a multi meter and solder you can usually make one good rectifier out of 2.

I unplugged the alternator and I checked amp flow from the battery using a test light first and then a multimeter. The test light would emit a dull glow briefly and then out. It would do this each time I re-connected. The multimeter tested 0.008 amps. It would briefly read 0.03 amps and then quickly settle back to 0.008amps. I assume there is some kind of pressure build up. There is nothing on in the car I don't know why there is a current reading at all.

I like the idea of spending a few bucks and maybe a couple of hours and its all fixed. Given there will be 3000 of these crappy Hitachi units hitting the streets over the next couple of years there could be a part time job in it. However, as I have no idea what I'm doing it will likely end similar to some of my other attempts. I waste a weekend working on it only to take it to someone who charges me for the time to fix what Ive stuffed up.

I realise the US units may be poor quality. However, I'm pretty unimpressed with the Hitachi. I bought it new, has been in the 110 since 2006 and has only travelled about 70,000km. The dud replacement Hitachi looks newer than my old one.

Ive compared the physical measurements in the ebay listed alternators and they seem identical to the Hitachi. So the 70 amp Rodeo one could be a good alternative. Ive been quite happy with 70 amps. I think the County alternator was only about 35 amp.

Originally Posted by rar110

I unplugged the alternator and I checked amp flow from the battery using a test light first and then a multimeter. The test light would emit a dull glow briefly and then out. It would do this each time I re-connected. The multimeter tested 0.008 amps. It would briefly read 0.03 amps and then quickly settle back to 0.008amps. I assume there is some kind of pressure build up. There is nothing on in the car I don't know why there is a current reading at all.

I like the idea of spending a few bucks and maybe a couple of hours and its all fixed. Given there will be 3000 of these crappy Hitachi units hitting the streets over the next couple of years there could be a part time job in it. However, as I have no idea what I'm doing it will likely end similar to some of my other attempts. I waste a weekend working on it only to take it to someone who charges me for the time to fix what Ive stuffed up.

I realise the US units may be poor quality. However, I'm pretty unimpressed with the Hitachi. I bought it new, has been in the 110 since 2006 and has only travelled about 70,000km. The dud replacement Hitachi looks newer than my old one.

Ive compared the physical measurements in the ebay listed alternators and they seem identical to the Hitachi. So the 70 amp Rodeo one could be a good alternative. Ive been quite happy with 70 amps. I think the County alternator was only about 35 amp.

thats normal, the initial draw is things like radios charging capacitors and things like that.

the invite for saturday is still open.

OK, that's a good result. If you plug in the alternator and disconnect and you get .008 amps. A typical car battery 40 amp /h could discharge .008 amps , for 5000 hours, about 6 months and still probably start a car. ( ignoring internal leakage) . I expect a landy will have a much bigger battery, say 100 A/H & 600 to 1000 CCA.
Example I have left the internal light on in my car overnight , (12 hours x .5 amps = 6 amp hours ) another time I pulled over for a sleep under street light , and i my headlights were still on in the morning, ( 4-5 hours 12 amps, (60 amp hours) ), My car still started OK.

A current l like .008 A, could be the electric clock in your car, 008 A is the same as zero in practical purpose.
It looks like the alternator is all good, it also looks like you have no leakage.
Try leaving the light & /or altimeter in the circuit overnight n the circuit, and a check a few times in the evening and in the morning. Check the voltage of the battery each time.

But if you can't find an external leak, you need to consider the battery. But you said earlier, when you disconnect the battery it is still charged the next day, it looks like an external leak yet to be discovered. Sometimes it takes a while in observation to get the info you need.
Do you have a wiring diagram?, I had mine printed on two sheets of A3 paper and colored in the lines etc, makes it easy to read for us whose eyes are not so good. An auto electrician has a test rig, he can check your alternator thats not in the car as well. Hang in there simmo

Originally Posted by simmo

OK, that's a good result. If you plug in the alternator and disconnect and you get .008 amps. A typical car battery 40 amp /h could discharge .008 amps , for 5000 hours, about 6 months and still probably start a car. ( ignoring internal leakage) . I expect a landy will have a much bigger battery, say 100 A/H & 600 to 1000 CCA. Example I have left the internal light on in my car overnight , (12 hours x .5 amps = 6 amp hours ) another time I pulled over for a sleep under street light , and i my headlights were still on in the morning, ( 4-5 hours 12 amps, (60 amp hours) ), My car still started OK. A current l like .008 A, could be the electric clock in your car, 008 A is the same as zero in practical purpose. It looks like the alternator is all good, it also looks like you have no leakage. Try leaving the light & /or altimeter in the circuit overnight n the circuit, and a check a few times in the evening and in the morning. Check the voltage of the battery each time. But if you can't find an external leak, you need to consider the battery. But you said earlier, when you disconnect the battery it is still charged the next day, it looks like an external leak yet to be discovered. Sometimes it takes a while in observation to get the info you need. Do you have a wiring diagram?, I had mine printed on two sheets of A3 paper and colored in the lines etc, makes it easy to read for us whose eyes are not so good. An auto electrician has a test rig, he can check your alternator thats not in the car as well. Hang in there simmo

Thanks for the detailed reply Simmo, but it draws 0.008 amps with the alternator unplugged. The other night the RACQ got a reading of 3amps when it was plugged in.

Hi sorry must have mis- read your info, 3 amps while the Alt is plugged in is big, it also means your battery is may not be be charging properly while your using the car there is a leakage to negative side all the time
When the car is cooled down you should be able to feel the cable/back of the alternator being warmed up. ( same as a 36 -40 watt lamp in use.
If you disconnect the battery and put the test light in the line it should burn brightly.
If you have two alternators with the diodes knackered , you can replace the diodes but it's not so easy for get the alternator apart, but if you're patient and have thee hands you probably can, plus you might as well put new bearings in it ( cheap), and check it doesn't need new brushes , Me I'd take it and ask the auto elect to fix it for me. In my case about 150,000kms, I didn't bother, i just bought a new Japanese alternator about 70 amps i think with exactly the same configuration. I had to machine the landrover pulley hub a little bit thinner so the nut could go all the way on. There was plenty of metal there.