Alternator or Regulator stuffed?

[TurboRA28]

Hi all, was driving home from work tonight in the 4runner and noticed the charge light was on.

I've checked over everything, alternator belt and plugs etc and everything is fine there.

It uses an external regulator which i'm not real cluey on.

How do I diagnose if its the alternator or regulater that is stuffed?

With engine running, volts are 12.2 on the battery. Not sure if this would slowly drop or not after running it for longer.

Cheers
Joel

[roadsailing]

when my sprinter had a 4AC the charge light would come on, and this wierd whirring noise would come from the bonnet.

my immediate thoghts were regulator is stuffed, alternator is stuffed. i replace the regulator because it was easier, and the problem went away.

the original regulator was this huge box with coils, magnets and wires inside, the one i replaced it with (from my spare sprinter, which is older than my road one - assuming it was a replacement part) was tiny, and solid state - encased in black resin.

dont really know how to check it, my advice is to replace the reg if you can get one cheap.

[o_man_ra23]

Theres a huge writeup about this in the haynes celica manual on how to diagnose faults in the charging circuit, and it goes on about checking resistances, and voltages etc etc. First things first, start the car, disconnect the battery positive terminal, and check the voltage there. while revving with no lights etc on, it should go up to 14.4-14.8 volts. If it doesnt go all the way up, your alternator is probably lacking. If it goes above this, your regulator is stuffed. If its around that range, then you will have to perform further checks. Dont discount the possibility that the part of the regulator that detects when there is a faulty current etc and hence turns on the charge light may be faulty. Last i checked a regulator is about $70 new. Alternator for a carburetted R motor with internal regulator is about $235.

Cheers, Owen

[TurboRA28]

Thanks for the replys guys.

ShinyBlue , mate there is some odd noise also, and excessive ignition kinda noise through the radio. Sounds like could be regulator.

I'll try that first.
Cheers
Joel

[river]

Hi,

Could also be the alternator. Does the noise change with the revs of the engine. You could have a blown diode in the alternator or worn brushes.

Stick a long screwdriver, metal end, against the alternator while the engine is running and put your ear to the handle. ANy sounds will transmit through the driver and you'll get a good idea of where the noise is coming from. This is a great way to find which tappet is noisy. Also you can try this on your regulator. This will help you determine where the noise is actually coming from.

Also you can put a voltmeter across the output of the alternator and see if you're getting over 14VDC. If not, then your alternator needs servicing. If the voltage fluctuates wildy then you also need to get your alternator serviced.

As mentioned, hopefully the alternator is okay 'cos regulators are cheaper to replace.

seeyuzz
river

[mic*]

Low voltage, usually diodes, bushes, coils. Erratic - regulator.

You can make a visual assement of the state of your windings which will give you an idea of the bushes too.

I reckon if it aint obvious with the basic multimeter & revs checks, pull it out and hand it to your autolecky - as long as he's trustworthy you should get out of there with a new regulator or repacked diodes for under $100. If it needs to be re-wound u usually do a swap for another which is already done might set u back $120 instead.

Some of the manufaturers of "new" ones are just acid cleaning, rewinding and repacking old ones anyway.

[oldcorollas]

Hi,

Could also be the alternator. Does the noise change with the revs of the engine. You could have a blown diode in the alternator river

the way to test for this is to use a jaycar battery monitor circuit.. the one with 10 LED's controlled by a 3914? IC...

it responds to voltage very well, and everytime i blew a field diode (which was... pretty often ) i would see the LEDs behaving badly.. ie you can see the voltage increasing acros the scale (in about 1 second at idle) and then go to low voltage and repeat .. faster with more rpm..

if you have a voltmeter than does not do averaging, or a fast response multimeter, then you may be able to see it also...

it could also just be a broken solder joint from the field diodes...

usually.. for me... if the normal battery voltage is around 11.5-20V, and then when running it is 1/2 to 1 volt higher... it's a field diode...

it could also be brushes arcing of they are almost worn down, and this is of course easiest to check.... this can (i think) also affect the regulator btu making it turn on and offf constantly, and arc up over the contacts.. perhaps...

good way around all of this is to adapt a Bosch style with internal reg...(ala KE70/XF falcon)

Cya, Stewart

[mic*]

Stu,

Do you suggest that alternator coz its good or coz its common?

I've had two of em and they both died within 12 months. They were adapted onto an excel. One was for a XF fairlane so it had a higher output for all the fancy shit. They were both rebuilt items from different places.

I have a thoery that im sure you will dispell, that in an east-west four the thing is spinning the opposite way to on the inline 6, consequently the external cooling fan has a lot of drag. In the excel it almost made the thing sound like it had a little turbo the way it whistled. I think this might load the bearings up more and it gets to hot as well as the fan not pushing air where its meant to. But they croaked quick.

[roadsailing]

its possible, and easy to check

[mic*]

It didnt take much convincing me when the fan became that stressed that it threw a piece straight up and THROUGH the bonnet.

Wouldn that have been fun if it came off towards the firewall instead... The firewall is about as thick as the rest of the body panels...

[oldcorollas]

Stu,

Do you suggest that alternator coz its good or coz its common?

I've had two of em and they both died within 12 months. They were adapted onto an excel. One was for a XF fairlane so it had a higher output for all the fancy shit. They were both rebuilt items from different places.

I have a thoery that im sure you will dispell, that in an east-west four the thing is spinning the opposite way to on the inline 6, consequently the external cooling fan has a lot of drag. In the excel it almost made the thing sound like it had a little turbo the way it whistled. I think this might load the bearings up more and it gets to hot as well as the fan not pushing air where its meant to. But they croaked quick.

well... afaik, only honduh FWD motors spin backwards... most motors are designed to spin clockwise when viewed from the front... unless the hyundais run backwards like the honduhs?

for me they have been good. oldstyle denso alts kept dying from vibration.. the race solution is to embed the diode pack in epoxy, but i cbf doing that

i had both KE70 bosch, and a modified KE70 with XF guts into it, and neither died from vibration failure. they are common, but the main reason i like them is that the brush/regulator pck comes out so easily.. to change brushes, you óften don't even need to loosen the fan belt!! toooo easy... as well as not needing external regulator.. less wires.

you may have had the drive ratio wrong.

old style "large" alts and new "compact" style alts have different maximum speeds (i think old is 16,000rpm and new is 20-22,000rpm? or maybe it's 12 and 16.. it's on the Bosch site.) overspin them and they sound bad and die quickly....

as far as air.. the air comes in the back of the alt and goes out the front, where it is thrown, centrifugal style, outwards..
the Caldinas have a cold air inlet that runs to the back of the alt to make sure they get cold air going into them.. something to think about..

Cya, Stewart

[oldcorollas]

It didnt take much convincing me when the fan became that stressed that it threw a piece straight up and THROUGH the bonnet.

Wouldn that have been fun if it came off towards the firewall instead... The firewall is about as thick as the rest of the body panels...

as for air stressign the fan.. nto really possible... the air resistance compared to the strength of the fan is negligible. what is more likely is that the blades died from imbalance and resulting fatigue.. rather than any amount of air resistance....

which direction were you turning the alt? which way was the fan designed to turn?

[roadsailing]

being an excel, it would have some form of mitsubishi engine in it.

and you are right, you can't overload a fan, you can overspeed a fan though.

the duct for the alternator is a good idea, as 4AGE alts can be somewhat hard to find.

[nb86]

i'd replace the reg first, shouldnt be more than $20 at the right place. then check the alt, if it's gone, go with the others recommendation, or even try a VT commodore alt. but make sure it's the bosch one. these are quite reliable and the reg and brushes come out as one unit from the rear of the alt by rmoving two phillips head screws. easy to change the brushes and if you're lazy the whole assembly (regulator and brushes) is about $50 from any auto spares shop.

[BradW]

First things first, start the car, disconnect the battery positive terminal, and check the voltage there. while revving with no lights etc on, it should go up to 14.4-14.8 volts.
Cheers, Owen

This is a good way to stuff your alternator. Everyone will probably jump in now and say they do it all the time and have never had a problem but I would never do it.

To check the alternator disconnect the plug on the back and put power to the "F" (field) terminal. You should get a small spark when you do this and if you have an ammeter, check the current draw on the field terminal ( should be approx 3 amps ). If there is no current draw then the brushes are probably stuffed. If there is current draw, start the engine and check the charging voltage ( with power still connected to the field ). It should be charging flat out (16 - 20 volts). Also check the voltage on the "N" terminal. This should read approx half of the charging voltage. If any of these readings are out then the alternator is stuffed.

If the alternator tests OK check the wiring to the reg and replace the reg if the wiring is good.

Good luck.