Thread: Battery Light Coming on

Originally Posted by surfingooner

....

Why would heat or a hot engine affect the bushes and regulator and whether they work or not ? Cheers, matt.

The most obvious reasoning would be thermal stress for the brushes(I think they're copper).
When cold they probably contact better, but then as they get hot as the shaft rotates they then don't make such good contact.

I always assumed that if the alternator works when cold and not when hot, it's usually the rectifier/regulator causing the issue. The electronics get hot as the engine gets hot and bam .. they just stop.

My 300 Tdi alternator does the same thing(with the exception that the battery light doesn't come on in mine!).
So from a dead cold(as in morning start) it works, then at some point(random) it stops(tacho stops dead).
If I start it again a few hours later with engine cold, eg. after an 8hr shift, it doesn't work.

The old one is in the shed now, waiting for a rebuild one day .. I replaced mine with a new one.

Thanks Arthur, my new brushes and regulator now arrived from Blighty, and I pick up later today the spanner tool (finally given in and bought first specialist tool) and a new drive belt, and "O" ring.

Good timing as has been getting progressively worse, when cold it only lasts 10 minutes till the light comes on, funny thing is that even after an hour drive with light on for most of it, it still manages to start - but not with usual gusto.

Saturday is the day, fingers crossed, always get nervous when you start a job not knowing if the fix will sort it out or whether it might need doing all over again.

But as always, thanks to this forum, I think I am doing the most logical attempt at repair before forking out for a re-conditioned unit and a whole load more dollars.

Cheers all.

Matt.

Originally Posted by simonmelb

See this page and the link halfway down with a PDF tutorial on how to rebuild your alternator.

Td5 alternator

Just start with the bit up to replacing your brushes (and regulator also if you wish) and also clean the slip rings. 95% of the time its just the brushes need replacing and the whole thing cleaned of oil.

Parts available on eBay e.g. here: DEFENDER & DISCOVERY 2.5 DIESEL TD5 1998 - 2006 ALTERNATOR REGULATOR & BRUSHBOX | eBay

This seller sends instructions as well. Mine is original at 305kM with just brushes change and a clean only, about 15,000km ago.

Simon, did you ever do that 14.7 volt thing? If so, how did it work out?

Hmm. Mine had the light come on one morning going to work. Boy does the battery go flat quickly on those things! Anyway, I pulled it and took it to a large sparky mob in Dandenong. They told me it was the rectifier and they couldn't get one. So I bought a second hand one off fleabay and have my old one sitting around. That tutorial Simon linked to has inspired me to have a go at fixing it.

Originally Posted by johntins

....They told me it was the rectifier and they couldn't get one. So I bought a second hand one off fleabay and have my old one sitting around. ....

that's what you need LAND ROVER DEFENDER TD5 1998 - 2006 ALTERNATOR REGULATOR - RECTIFIER & BRUSHBOX | eBay

Originally Posted by johntins

Hmm. Mine had the light come on one morning going to work. Boy does the battery go flat quickly on those things! ....

I guess it's all the electronics and fuel pump.
Fuel pump alone = about 10 amps .. so 120w .. equivalent to having your headlights on.

I guess the one thing that I like about the simple 300 tdi.
I ran mine without a working alternator for a bit over a week(waiting for the new one to come) had to deal with low light levels and rain too ..
And having the dual battery with the manual switch made life easy to live with too.

Originally Posted by AK83

I guess it's all the electronics and fuel pump.
Fuel pump alone = about 10 amps .. so 120w .. equivalent to having your headlights on.

Plus it was dark and raining, so lights, wipers, heater. Pulled up at the lights and it just stopped.

My problem got progressively worse, light would come on after 10 minutes. Picked up a new belt and washers on Thursday and all went to sh*t driving home. First suspension light then abs light, loads of pinging, and finall m&s lights flashing and limp mode. Had a nightmare getting home in rush hours, starting at lights on a hill etc.

through pall ing finally made it home, but got stuck half way up driveway. Did a jump with wife’s car but eventually made it up to top of driveway but was painful, it hurt the car.

anyway, made a tool to hold the nuts and got the fan off last night, bashing the spanner wouldn’t do it, so another trip to Bunnings, but it is not hard to make a tool yourself and much cheaper than buying one.

Spent all day getting the job done today, it is a pig of a job, my arms all cut and sore, mostly from the battery plastic ,surround, but it is all done and working and no ligso far. The sun shone,then it ****ed down most the afternoon, got soaked putting it all in, but need the car tomorrow.it took a long time getting out, much quicker putting all back in.

I degreased the whole unit and let it dry, very oily and gunky, I am amazed they actually work as long as they do. Worst part was starting it, not knowing if the light would come back on and it would all have been for nothing, but has worked and am well happy about it. Left it running for a while to begin with and was so nervous when looking at the dash to see if it had come back on. Fingers crossed,took it for a 20 run and all good so far.

So thanks all for all the help, especially Simon, and pleased changed the belt too, a very easy job once you have the right tools. I will post a photo of the tool I made in the next couple of days, Matt.