Thread: Alternator Failure?

I get the explanation, but how do I do it?

Regards

I tried to get a new alternator for my 3.0l when they did the timing belt, in case there was still a problem like there is with the 2.7's. Apparently there has never been a failure in Australia, with some cars up near 300,000km in Perth, so there may be some hope. However, the bad news is that you can't buy an alternator quickly if they do fail because there are none kept in stock.


I think I will try to work out if it can have the same problem as the 2.7 and if it can, put in the separate fused wire as Graeme suggests. No sure how to check it yet, especially if Graeme hasn't yet worked it out!

Does the 2.7 D4 have the same issue as the D3?

I am sure i read somewhere the D4 2.7 as well as the 3.0 wiring was upgraded.

Originally Posted by ytt105

I get the explanation, but how do I do it?

Remove the cable from between the alternator and starter motor (cut the end at the starter motor) then run a cable of the same capacity as the original alternator cable parallel to the starter cable as it winds its way around the bottom of the front of the engine to a maxi-fuse that you've mounted near the battery that's connected to the battery positive terminal.

A maxi-fuse holder could probably be installed mid-way along the existing alternator cable if there is adequate access for a crimping tool. That the fuse would be accessed from under the vehicle should not be a problem because ready access is not required.

Originally Posted by Graeme

For the 3.0's 180A alternator I have chosen 200A with a 210A as a backup when I get to fit the cable to my D4.

However I don't know if the 3.0's alternator is fitted with Zener diodes that deteriorate with use and usually fail short circuit rather than open circuit as LR went out to tender for a new alternator for the 3.0. Only some manufacturers use Zener diodes as the main rectifier diodes - others use Zener diodes in the regulator circuit to cause alternator shutdown to protect ecus if the voltage runs away due to the battery becoming disconnected or goes open-circuit.

Graeme, if I am understanding this, with the right Zener diode design, a failed alternator would not cause the catastrophic battery failure people have experienced. Have I interpreted this correctly? I guess this would be difficult to find out.

Also, I don't understand the 210A backup. Do you mean in case the 200A is not quite big enough once installed & then replace with 210A?

Cheers,
Scott

I had an alternator failure 4 weeks ago, red light came on as we were leaving an area around Harvey, I thought theres nothing I can do will just have to run on the battery and see how far I can get. Got to Waroona had a look and yes the electrical smell was there but we kept on until just past Placid Ark fuel and all the dash lights lit up telling me that systems were shutting down, we lasted until the rail crossing just south of Pinjarra and that was it no nothing.
Got flatbedded home, on the Sunday I took the battery out and there was absolutely nothing in it, hooked it up to my 1Kva Honda genny and let it run all day, meantime I removed the alternator which was of course kaput, I've since learned that when they give out they aparently short curcuit thus the smell.
Got on to my LR indy on Monday and picked up a new alternator that afternoon (Denso), fitted it to the car Monday night and was back on the road about 8.30 that night.
I'm glad it happened when it did, the car has done just short of 300K and these are the things I need to replace prior to setting out soon.
Cost? Flatbed $220, alternator $690 so I am happy

Some alternator manufacturers use Zener power diodes to provide the over-voltage shut-down facility whereas others use Zener diodes in the regulator circuit to cause voltage shut-down. Zener diodes, otherwise known as avalanche diodes, conduct in the reverse direction once the voltage exceeds their trigger level. They also deteriorate with use and faster if operated near their maximum current rating whereby the trigger voltage level slowly lowers so eventually will reverse conduct at normal operating voltages.

The 210A is in case the 200A blows in normal use. The 3.0's alternator is rated at a minimum of 180A, as specified by LR. To achieve this the alternator will invariably o/p at a higher rate when cold. Hence a 200A fuse may not be high enough under high load conditions, such as winching in cold weather. However if the fuse rating is too high then the wiring within the alternator may not allow that much current to be drawn so would not blow. Hence one just above the alternator's maximum would seem appropriate. I've been meaning to discover what fuse is used in the Territory and its alternator's o/p as a guide to an appropriate fuse.

This may seem like a stupid question, but could you not fuse the battery end ? It would certainly make it easy to put the fuse in a out of the way place.


This is something that I would be looking at doing, has anyone posted a thread/tutorial of fusing the alternator.




Cheers Ean