Alternator 2 pin or 3 pin

[lesternester]

My 2003 MG ZT diesel has stopped charging,the battery light has come on and the night before this the lights were fading up and down, so i am assuming it needs a regulator/brushes.(i have a battery charge indicator plugged into the lighter socket and when the battery light does go out for a minute or two,it does go over the 14v mark but whith the light on its showing 11.5v).
The lead to the alternator is a 3 pin but there is only 2 pins on the alternator,have been looking on ebay and some of the alternators that have a 3 pin plug also have 3 pins on the alternator and other only have 2 like mine, does it matter which one i get as long as it accepts a 3 pin plug.
Thanks.

[MSS]

the regulators are different for the two versions, so it does matter.

It is easy enough to check which you have with a telescopic mirror.

[Devilish]

You can plug a 2 pin loom plug into a 3 pin alternator socket because it just does not use pin 3, I have fitted them. But you cannot plug a 3 pin loom connector into a 2 pin alternator socket because it needs pin 3.

You need a 3 pin alternator

[lesternester]

Thanks for the replies but maybe i'm not explaining my problem clearly enough,the plug on my wiring loom has 3 female connectors but the alternator only has 2 male connectors and a blank space for the third one,but when looking to buy another alternator some of them are the same as mine with 2 males and a blank and others have 3 males,both of these are known as a 3 pin alternator due to the wiring loom plug being able to take three pins.(i know there are 2 pin alternators but the wiring loom for these only have a 2 pin female socket and only 2 male pins on the alternator and has a different shaped socket).
So can i use an alternator that has three male pins, as my wiring loom plug has three female connectors or do i need one the same as i have got,with 2 male pins and a blank space or doesnt it matter.
Help would be appreciated as i wouldnt want to buy the wrong one.

[lesternester]

Thanks for the replies but maybe i'm not explaining my problem clearly enough,the plug on my wiring loom has 3 female connectors but the alternator only has 2 male connectors and a blank space for the third one,but when looking to buy another alternator some of them are the same as mine with 2 males and a blank and others have 3 males,both of these are known as a 3 pin alternator due to the wiring loom plug being able to take three pins.(i know there are 2 pin alternators but the wiring loom for these only have a 2 pin female socket and only 2 male pins on the alternator and has a different shaped socket).
So can i use an alternator that has three male pins, as my wiring loom plug has three female connectors or do i need one the same as i have got,with 2 male pins and a blank space or doesnt it matter.
Help would be appreciated as i wouldnt want to buy the wrong one.

[MSS]

The two alternators - 2 pin and 3 pin - are interchangeable.

But, the 2 pin alternator is 120A whereas the 3-pin one I believe is only 100A or 110A.

I would buy the 2-pin one given a choice.

If you have the time, why not get your current one rebuilt? There is a place in Ipswich that I can recommend but they do not do a postal service.

[lesternester]

[QUOTE=mss;2592143][I]The two alternators - 2 pin and 3 pin - are interchangeable.

But, the 2 pin alternator is 120A whereas the 3-pin one I believe is only 100A or 110A.

I would buy the 2-pin one given a choice.

If you have the time, why not get your current one rebuilt? There is a place in Ipswich that I can recommend but they do not do a postal service.

Cheers ,will get it off and try match it with a like for like and play safe.

[COLVERT]

https://www.the75andztclub.co.uk/forum/imagehosting/8178546c5ae9f0ef6.jpghttps://www.the75andztclub.co.uk/forum/imagehosting/8178546c661cb89b9.jpg

[COLVERT]

https://www.the75andztclub.co.uk/forum/imagehosting/8178546c661cb89b9.jpg

[DMGRS]

You need the 2 pin. We have them here:
https://www.dmgrs.co.uk/collections/electrical-electronic-parts/products/rover-75-mg-zt-cdti-alternator-regulator-and-brush-kit-fits-yle000260-and-yle102500

It's worthy of note that while this fixes about 4 out of 5, the 1 out of 5 will have another fault such as a failed winding or completely worn slip rings.
We're happy for you to return of course, if this is the case. :)

[Trisman]

I went through this only the other week...

If you plan to replace the complete alternator, either type will fit the diesel engined cars. So it makes sense to fit a later, higher output alternator.

So, the later two pin or the earlier three pin alternators will fit & work, regardless of whether or not your car's wiring loom has a two or three pin plug.

Replacing a complete alternator is apparently a bear of a job...

I decided to replace just the regulator, without taking the alternator off the car.

It's is a fiddly job, but as I mentioned, is apparently a lot quicker & easier than removing & replacing the alternator.

It took me around 3/4 of an hour on a cold day. The only difficult bit (part from keeping my hands warm!) was removing the gloop the manufacturers see fit to smear on the two small connectors. (See the first picture above in Colvert's post).

The regulators are not interchangeable. You have to get a three pin one for the earlier, three pin alternators, or a two pin one for the later two pin ones.

In my case, I did what DMGRS suggested & obtained both types of regulator. Turned out that my first purchase (a three pin regulator) was correct & I didn't even need to take the later two-pin type out of it's box! It was sent back for a (pre-agreed) refund.

[lesternester]

[QUOTE=Trisman;2592454]I went through this only the other week...

If you plan to replace the complete alternator, either type will fit the diesel engined cars. So it makes sense to fit a later, higher output alternator.

So, the later two pin or the earlier three pin alternators will fit & work, regardless of whether or not your car's wiring loom has a two or three pin plug.

Replacing a complete alternator is apparently a bear of a job...

I decided to replace just the regulator, without taking the alternator off the car.

It's is a fiddly job, but as I mentioned, is apparently a lot quicker & easier than removing & replacing the alternator.

It took me around 3/4 of an hour on a cold day. The only difficult bit (part from keeping my hands warm!) was removing the gloop the manufacturers see fit to smear on the two small connectors. (See the first picture above in Colvert's post).

The regulators are not interchangeable. You have to get a three pin one for the earlier, three pin alternators, or a two pin one for the later two pin ones.

In my case, I did what DMGRS suggested & obtained both types of regulator. Turned out that my first purchase (a three pin regulator) was correct & I didn't even need to take the later two-pin type out of it's box! It was sent back for a (pre-agreed) refund.

I did wonder if the regulator could be changed while still in place but just taking the plug off and on again to check the pins was restrictive enough but if you've done it,i will take this route.Any handy tips would be gratefully accepted.Thanks for the reply.

[Trisman]

Any handy tips would be gratefully accepted.Thanks for the reply.

I received some helpful tips from this very forum when I asked about doing the job!

See: Diesel Alternator thread (https://the75andztclub.co.uk/forum/showthread.php?t=277875)

Best was to use a magnetic probe extension thing. It came in very handy, as did ensuring the tools I used were magnetic.

Be extra careful with the (non magnetic & tiny) brass nuts. Though if your car has the later 2 pin regulator, it look like they won't be quite as small.

Hopefully, the 2 pin regulators don't make use of the black gloop either.

I was able to get away without loosening either the filter housing or PAS reservoir, but I did loosen the dip-stick tube.

To fit the new regulator over the slip rings, I used a length of masking tape to hold the bushes up against their spring pressure. Once the regulator was in place, I gently pulled the masking tape from between the brushes & the slip rings.

You'll see what I mean when you try to fit the regulator without compressing the brushes...!

Good luck!

[Snagger]

See links in my signature for diesel alternator solutions ;)

Snagger

[Clickernick]

Well,,,, what can I add?.
Well,, three days ago my MG battery light started to come on and go off intermittentlywhilst diving and then on Wednesday stay on all the time. Suspecting a now duff regulator (been here before), following advice here, I did a quick check on the plug to the alternator and upon seeing 2 female connectors I immediately ordered a 2 pin jobbie of the Bay!:bowdown:

It arrived on Thursday and so I promptly set about the tortuous task of removing the reg.:o
All went well until I could not find the regulator middle nut. I kept looking at the new part as a reference. To make matters worse, Someone (Valeo) had smothered the area with black gunge making it impossible to find the said Nut.:mad:

Cursing the French and scrapping my knuckles, pulling like an A4 Pacific, I managed to wreck the whole thing, bits everywhere,,,,,, only to discover that although I had 2 connections in the plug, the reg was a 3 pin affair, hence there was no centre Nut but 2 small 7mm nut heads to remove. :eek:
Damn and blast!! Check the regulator pins not the plug!!:duh::duh:

Too late now, I had trashed the rectifier as well!! Doh!!! (more cursing to follow, and now apologies in abundance to the French):getmecoat:

I have now ordered a used 100260 2 pin alternator £40 which I will, for my sins, refurb with the already purchased 2 pin regulator along with new slip rings and new bearing from Matt at DMGRS.
A good YouTube video has shown how to do this so maybe this time I’ll get it all right!!
https://youtu.be/f56-26I6idc
Why does it always happen in January,, please someone tell me!!!:mad::mad:

[Clickernick]

Well,,, after a bit of a wait, i procured a second hand genuine 120 amp 2 pin alternator of the Bay with 2011 stamped on it so its a low miler.

I changed the regulator brushes for the new set bought prior, I was going to do the whole thing properly and change the slip rings and bearing but as it was in good shape with minimal wear to the commutator, I just striped the alternator down, thoroughly degreased it (Jizer) and threw it in the dishwasher for an intense wash,, it was a real grotty state. I think a previous owner had tipped a lot of engine oil over it or had a leaky oil filter canister.

I decided to follow the above method from Snagger and go in 'from the top'.:drool4:

I followed a print out of the above posters method and as i have a rather good high-lift alloy professional jack and some decent axle stands it was a no brainer.

The weather today was excellent if a bit blowy but all went to plan.:p:

Being able to raise and lower the engine at will made it all work very well and no dirt in my eyes from doing it all underneath.

The only help i needed was to push the engine backwards enough to allow enough space to extract the alternator up out of its hole, and then again to lower the replacement one in.:bowdown:

I had a couple of spare gates belts to hand bought of a member here and as the AC one was seriously shot, (166,000 miles) they both got changed as a bonus.;)

The whole job took 5 hours and although I said never again, i would do it the same way every time.

[COLVERT]

Well,,, after a bit of a wait, i procured a second hand genuine 120 amp 2 pin alternator of the Bay with 2011 stamped on it so its a low miler.

I changed the regulator brushes for the new set bought prior, I was going to do the whole thing properly and change the slip rings and bearing but as it was in good shape with minimal wear to the commutator, I just striped the alternator down, thoroughly degreased it (Jizer) and threw it in the dishwasher for an intense wash,, it was a real grotty state. I think a previous owner had tipped a lot of engine oil over it or had a leaky oil filter canister.

I decided to follow the above method from Snagger and go in 'from the top'.:drool4:

I followed a print out of the above posters method and as i have a rather good high-lift alloy professional jack and some decent axle stands it was a no brainer.

The weather today was excellent if a bit blowy but all went to plan.:p:

Being able to raise and lower the engine at will made it all work very well and no dirt in my eyes from doing it all underneath.

The only help i needed was to push the engine backwards enough to allow enough space to extract the alternator up out of its hole, and then again to lower the replacement one in.:bowdown:

I had a couple of spare gates belts to hand bought of a member here and as the AC one was seriously shot, (166,000 miles) they both got changed as a bonus.;)

The whole job took 5 hours and although I said never again, i would do it the same way every time.

After the dish washer how did you re-oil the bearings ??

[Rp61973]

My alternator light decided to come on whilst driving last year, I limped the old girl home an changed the brush-pack. Unfortunately after shelling out £35 and spending around 1 hour skinning knuckles fitting it, I find that it made no difference and the alternator was U/S.

I took the alternator out and had this rebuilt at a local workshop in Basildon. Unfortunately they wouldn't use my brand new brush pack as they couldn't guarantee it. They rebuilt the unit for a modest £95. At the same time, I had the weeping power steering pump re-built. Changing the alternator isn't the hardest job I have done, but it is time consuming with dropping and lifting the engine on the jack to access the bolts.