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Alternator problem?

Daniel Petersen

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Joined
Mar 12, 2017
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australia
gday guys, new to the forum here! I have a much loved 79 series as my work car with a 1HZ motor in it and am after a bit of help!
To be honest my personal car is a (don't shoot me), Patrol so I don't know a whole lot about the land cruisers, only what I have picked up on my work ute over the last few years.
Anyways more to the point here!
A few weeks ago I noticed the glow plug light coming on intermittently while the car was idling or driving. Then after a few days when trying to start the car it would be abit of a struggle, it was like it hadn't had a chance for the glow plugs to come on and was being started on a cold morning, but this went on every time the car was started.
Now still having both the above issues, Iv gotten a flat battery. Jump started her and drove around for a few hours and battery is still flat.
Now Iv been parking it on a hill every day so that I can roll start it to get to work!
Usually I'd go to a mechanic but I live four hours from Alice Springs so I'm going to have to try and fix whatever it is myself!
The only other problem I have had recently, and I don't think it could be linked but the air conditioning belt snapped and I am yet to replace it.
Any advice would be very much appreciated and sorry for the very long post!
 
Hi,

It sounds like your alternator is not charging.

I don't know this vehicle but if your AC belt has snapped maybe it also does the alternator. Can you post a photo maybe?

If not then try removing the plug from the back of the alternator and checking for corrosion. Try wiggling it. You really need to check the voltage at the battery terminals as this will show you what the alternator is doing. If the truck has a voltmeter in the dash it will show some drop in the voltage. You should be getting 14.4v when charging. Can you get hold of a multimeter and check the voltage?

If you continue driving it you won't do the battery any good and it will give out at some point and leave you stranded with a flat, over discharged battery.
 
As above get a multimeter and check what's happening at the battery, also before buying a new alternator check the connections on the rear of the alternator and also check out the brush pack as these can be replaced instead of buying a complete unit, you tube has lots of videos that show how to work on your alternator.
 
Will check it out with the multimeter tomorrow morning.
Can I put the multimeter on the alternator to check the output or just at the battery?
The belt is just for the a/c, there's a second for the alternator.
On the volt gauge on the dash of the car it shows below 12 volts (obviously why it won't start), but once started it goes up and shows around 14volts while it's running.
 
Have you tried a different battery ? Not sure if the Patrol one will fit, but might be worth a try.
 
The voltmeter on the dash sounds like it is charging but there is clearly something wrong. Test at the battery, both on the actual post itself and the clamp on the post. Check for poor connections on the battery terminals and any sign of looseness or heating. It may be a bad battery or poor connection, it could also be something draining your battery if the alternator is charging correctly which it sounds like it could be.
 
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A couple of pieces of info to help you diagnose:
If the battery voltage, measured directly on the posts, goes up from under 12.4 to over 14 immediately after starting, the battery is bad. It means the chemistry isn't working.

One difficult condition to diagnose is a shorted diode in the rectifier. In that case it looks like the alternator is charging, but not quite enough. And the battery never reaches 14.2 to 14.4 as it should. The rectifier is inside the alternator, and can be changed easily.

Also, check engine and battery ground straps, battery terminals and that famous alternator plug.
 
Thanks all! Alternator is all good so it's deffinatly the battery, have ordered a new one for it.
Still unsure as to why the glow plug light is coming on though.
 
Check that the glow plug circuit isn't shorting out somewhere - an intermittent short would put the gp light on and kill the battery.
 
To add some meat to my last comment, it's unlikely to be a short circuit keeping the glow plugs on as cables and relays would soon heat up and drain the battery dead within a short time but there may well be something that is draining the battery. A shorted diode in the alternator (may have already been mentioned) could also drain the battery as could water in something like a towing indicator relay/bleeper or even in the trailer socket itself.

Of course, the battery itself could also be bad but this can be tested by a dealer.
 
Changed the battery and it's all good. Glow plug light only comes on when it should now.
Will keep a close eye on the battery over the next few months! Will let you all know if anything goes wrong! Thank you for your help
 
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