Alternator

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TheMegaMan

TheMegaMan

Well-Known Member
Posts
516
Location
Cambridge
Sorry chaps...more questions!

I think my alternator (Lucas LRA100) may be dead.

When turning on the ignition, the 'Charge' light doesn't illuminate and when the engine was running, I was still seeing just over 12V, not the 13.8V I was expecting.

Checking the yellow/brown wire at the alternator end, I'm seeing 12V there when the ignition is on, even when connected to the alternator. My understanding is that the alternator field winding should bring this down to closer to 0V, so if I'm still seeing 12V, does this mean the field windings are kaput? This does indicate that the bulb is OK, though.

I decided not to ground the yellow/brown wire to check the Charge light actually illuminates, as I can't recall whether it's a 12V or 6V bulb, and didn't want to zap it.

Thoughts?

Thanks,
Adam
 
On the assumption the alternator is dead (and the electronics on the back of the unit were looking very rusty and tired when I tried to clean it up when I dropped the engine back in, so it's possible I've damaged something), I've been looking at replacements.

Not hugely expensive.

How easy is it to get a pulley off an old unit? I guess it's one of those 'how long is a piece of string' questions, but is it just a case of undoing the bolt and it should drop off? Or is it a tapered shaft and I'll need a 'special tool' puller?

I ask because I've seen options for a 'brand new' ATP branded equivalent complete with pulley (but may well be the wrong size), or a reconditioned Lucas, but without a pulley, so for similar prices. Advantages of the Lucas one would be a trusted brand and I know it should fit and have the correct size pulley, but the down side is that I need to be able to get the pulley off the old one...

Thanks,
Adam
 
TheMegaMan said:
On the assumption the alternator is dead (and the electronics on the back of the unit were looking very rusty and tired when I tried to clean it up when I dropped the engine back in, so it's possible I've damaged something), I've been looking at replacements.

Not hugely expensive.

How easy is it to get a pulley off an old unit? I guess it's one of those 'how long is a piece of string' questions, but is it just a case of undoing the bolt and it should drop off? Or is it a tapered shaft and I'll need a 'special tool' puller?

I ask because I've seen options for a 'brand new' ATP branded equivalent complete with pulley (but may well be the wrong size), or a reconditioned Lucas, but without a pulley, so for similar prices. Advantages of the Lucas one would be a trusted brand and I know it should fit and have the correct size pulley, but the down side is that I need to be able to get the pulley off the old one...

Thanks,
Adam
Click to expand...
Can't comment on which one to buy but if you are binning the old one you can always introduce it to Mr Angle Grinder to get the pulley off :p
 
There's a place in kings lynn that fixes them, used to be called Cragmay's but I think they trade under a different name now.
 
If the charge light doesn't work (and the bulb is good) it's likely either the regulator or the field winding brushes. It's a quick job to check the brushes by removing the back cover and the brush box.
If you decide to replace the alt then the pulley can be a pain to remove. I got the pulley off my ACR with a three-legged puller, but it's not a taper fit, just a keyway. I don't think it matters if the pulley is a bit different in size - smaller is fine as the Landy engine is not exactly high-revving ;)
 
I would prove the bulb is getting a supply 1st before buying an alternator.
You could jury rig a seperate 12 V supply to the connection on the alternator that the bulb connects to to see if that makes the voltage come up.
 
Thanks for all the responses. I didn't mange to get on here yesterday, but good to see so many suggestions today.

@Marmaduke Could do, although I suspect I'll bu99er up the pulley or fan blades if I try that! The easy but to get at is unfortunately the bit I want to keep. But I take your point - if the body is likely to be scrap, I can be pretty brutal getting it off.

@ivanhoe , @Rodeo Joe Possibly, although not one that I know of. Given the weight of the thing, carriage (or petrol) is likely to expensive, and as replacement is less than £50, unless a repair is really cheap, it's likely to be more cost-effective to swap it out. I know a PO got the thing really submerged in mud, etc, so it's possible it's got other internal damage. Hence my preference to replace it.
 
ExMil109 said:
If the charge light doesn't work (and the bulb is good) it's likely either the regulator or the field winding brushes. It's a quick job to check the brushes by removing the back cover and the brush box.
Click to expand...
Bulb is definitely OK. After @steve2286w 's assurance it's a 12V bulb, I connected the yellow/brown to the alternator body, and it illuminated. So the bulb is good, I have a good supply to it, and the alternator body is earthed.

ExMil109 said:
If you decide to replace the alt then the pulley can be a pain to remove. I got the pulley off my ACR with a three-legged puller, but it's not a taper fit, just a keyway. I don't think it matters if the pulley is a bit different in size - smaller is fine as the Landy engine is not exactly high-revving ;)
Click to expand...
True - I was just hoping to avoid running out of adjustment and needing to find an alternative fan belt. :D

When I've resolved my fuel pump issue (I'll raise a new thread for that in a minute!), I'll get it off and take a closer look at it all. I was hoping to be fixing both problems in parallel, but I think I need to focus on one problem at a time, then investigate this properly off the engine.

@rob1miles Yeah, I saw that kit, but I'm pretty sure it doesn't look like the internals on my one. I'll check it again once it's off, and see exactly what I have. But something like that is an option...

Cheers, all!
 
Apologies if I missed anything is the bulb illuminating when the brown yellow connected to Lucas blade On alternator just with ignition on
And When revving does it go off and are you getting decent volts 13+
 
steve2286w said:
Apologies if I missed anything is the bulb illuminating when the brown yellow connected to Lucas blade On alternator just with ignition on
And When revving does it go off and are you getting decent volts 13+
Click to expand...
No, the bulb doesn't light at all, and I just see 12V on the alternator terminal when not running, whereas I think it should be pulled down close to ground (which is what would make the bulb illuminate).
When the engine is running, the bulb is still not illuminated, and the voltage is still sitting at 12V, so it's not charging at all.
 
Indeed they have, and I appreciate it all and will follow-up on them more in the next week or so. The pages in the bible look at bit scary, by the way, I don't have a 70A variable resistor to hand, not a convenient 110V supply! Some good stuff in there, but also assumes some equipment I can't image many domestic users have. I'll try and improvise!

Thanks for that link, too. Didn't spot an equivalent to mine there yet, but I'll look again later. I can certainly see the benefit in fixing some of those costing £250, but I'm questioning whether it's worth spending too much time on it when a replacement is less than £50. Maybe fix up the old one and keep it as a spare...
 
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