MQ/MK Turbo diesel charge voltage....

[Screwy]

Got my new SD33TD running the other day and noted that the charge while running even while revving the motor was only around the 12 volts mark.....

In my experiance most vehicles i have seen charge at 14 volts on the guage, my truck is only reading 12 volts on the guage, though its obviously not too low as the charge light isnt on.....

what could i change here to make a difference? what can i test? can i change the external regulator? test voltages?

just your opinions based on the way yours trucks are running is what im after.... its been a LONG LONG while since i last played with a diesel and am a little rusty...

screwy

[Vanne]

yep Screwy, yer right, mine runs at between 12-14 when its charging, but that also depends on the charge of the batt, if the batt is charged up, it will drop slightly towards the 12v.

cheers

[Wish I had coils]

what vanne said For the sake of a few bucks get some new brushes and bearings in the altenator, Your brushs might be on the way out.

[zer0]

bassically wish i had coils has it right the charge voltage should always be up around the 14 mark or a lil bellow ideally wat is suppose to happen if you alternator is charging properly is that if you battery is at a low voltage as soon as you start it even at idol if you put the voltmeter on the battery you should see the volts rise slowly .... best way to fix your prob reco the alternator

[badger]

check the wireing too. a corroded or bad joint can cause enough resistance to cause charge issues. if you test volts at the alt and at the battery this will give u a clue

[festy]

The SD33T alternator uses an external Hitachi mechanical voltage regulator, you can adjust the charge voltage with a multimeter, feeler gauges and a phillips head screwdriver.
Obviously, if your alternator needs new brushes or the diode pack is shot, adjusting the regulator won't do jack.
Or, you can chuck the mechanical one and use an aftermarket electronic regulator, well worth the $40.

Also keep in mind the voltmeter on the dash picks up it's voltage via pretty much every other component in the car (turn your blinkers on and watch the needle swing) so don't blindly trust it.

[Screwy]

good info guys, been too long since ive played with them to remember how deisels behave....

ill look into it abit more.

screwy

[Mintoy]

try adding a ground wire from your engine to the negative pole of your battery. if the volt meter reader does not improve. best to have your alternator serviced.

[mes]

ive only had my mq pickup for a short time, look around the wiring harnesses and that for wiring shorts, i had 1 not to long ago across the glow plug relay (they were always on) sent the battery flat. Brought a new one and it to was heading the same way, sumthing fishy was going on. This was causeing the volt gauge to read 12v at revs and about 10v-11v at idle, hope it helps

[Wish I had coils]

along the same lines got a mate with a 24v mq he keeps blowing steros up. checked the battery when running 14 volts charging and same with the other battery where the wires go to the stereo 12 volt but he keeps frying stereos has (cheap) driving lights 12 volt they have been fine but seem to bright for what they are.
Been told that it's only the starter that is 24v but the alt is 12v what do people think?

[festy]

alternator should be putting out 26-28v on a 24v MQ, it's not just the starter that's 24v - glow plugs, lights etc are all 24v from memory.

[Wish I had coils]

yeah thats what i thought but the batterys both charge at 12 ish volt if the head lights are 24 volt two how is it that he has not blown the driving lights. Sorry for the hyjack

[Screwy]

on 24 volt diesels the entire electrical system is 24 volts other than the one accesories cicuit for your cig lighter. thats the circuit to pick the stereo up from.

screwy

[V8Patrol]

grab ya multimeter

turn switch to 20V

start engine

put black multimeter wire onto negative terminal on the battery
&
red multimeter wire onto positive terminal on the battery


multimeter should read 13.8V


If the reading is higher than 13.8V then look into your regulator/rectifier

if the reading is lower than 13.8V then have the alt checked.






turn engine off and leave overnight

recheck the battery ( before starting the engine ) using the multimeter

reading should now be
12.5V ( or higher ) for a healthy battery
12.0V for an average battery
11.5V ( or less ) shows a battery thats ready for the recycling bin

(nb: readings may vary + or - up to 0.4V )

.

[pongo]

ALso, maybe try using 2 multimeters to double check the voltage. I always seem to damage them from bouncning around in the tool box.

This tip has saved me a few headaches in the past.

[Screwy]

i have problems.... not really sure why my charge light wont come on but i have no charge....
multimeter is reading the same on the battery whether the car is on or off which is low...... Battery is brand new, just getting flat slowly but surely....

going to replace the regulator first.... can you get after market ones? are they dear?

screwy

[festy]

My local auto electrician couldn't find a direct replacement for the Hitachi one in his books, so I just got an Ingram 831231 and swapped a couple of wires in the plug to make it work. It cost me $40, it's a common part.

[pongo]

IF the alt is shagged, usually the alt light and fuel filter light will stay on rather than not light up.

Have you actually checked the globes in the dash. Sometimes they are the resistence part needed to make the alt work.

A auto sparky should be able to diagnose fairly quickly.

[Nikolay]

i have problems.... not really sure why my charge light wont come on but i have no charge....

screwy

It is a reason to check out a charge lamp condition and a wire between lamp and voltage regulator. In case of interruption the signal to alternator exciting coil is lost.

nikolay

[RMP&O]

grab ya multimeter

turn switch to 20V

start engine

put black multimeter wire onto negative terminal on the battery
&
red multimeter wire onto positive terminal on the battery


multimeter should read 13.8V


If the reading is higher than 13.8V then look into your regulator/rectifier

if the reading is lower than 13.8V then have the alt checked.






turn engine off and leave overnight

recheck the battery ( before starting the engine ) using the multimeter

reading should now be
12.5V ( or higher ) for a healthy battery
12.0V for an average battery
11.5V ( or less ) shows a battery thats ready for the recycling bin

(nb: readings may vary + or - up to 0.4V )

.

sweet info Kingy, volt reading especially.

Is it the same for a 24v system...meaning same readings on each seperate battery?

My charge light came on yesterday but the volt gauge reads fine. 24v system volt gauge reading 28v. Checked stuff with volt meter and 28.1v from the alt which can dip to as low as 26.5v. One battery is sitting at 12.9v and the other is at 13.9v with the truck running. This goes up and down a little though on one of the batteries. With stuff on like lights/heater it drops to as low as 12.9v on one battery and also as high as 15.6v. I know I have one battery (the one the alt is hooked up to) that is over charging. That is the one with 13.9v but voltage goes up and down a bit on. This is a common prob in a 24v system with some 12v stuff hooked up right? IE, one overcharges? I been swapping them back and forth every few months to help keep them balanced.

With the truck off and batts isolated I get 12.5v-12.9v on each. So the batts seem fine.

My question is are my volt readings normal in a 24v SD33? And why would my charge light have come on if I am getting good readings. Had this truck for years, driven it plenty and have good red top optimas, the charge light has never come on before. I swapped batts yesterday from side to side but light is still on. If I disconnect the batts and let it run off the alt the light goes out. So I assume alt is fine especially because it is putting out 28.1v. Gauge in truck also seems fine because it says 28v which matches alt output. Is it that one battery has slightly less voltage than the other making the light come on and stay on?