Another alternator problem?

[Harve]

Hi all,

I have a problem with my stag. I thought it was a fault with the immobiliser but it turns out there may be another problem.

Basically the car had been left stood for a while when I was away. On return the battery was completely dead. I jump started the car and all was fine, i disconnected the other car and let the car warm up properly. However 2 minutes later the stag just died. Tried again and the same problem happened. When I tried athird time I noticed the voltmeter in the dash read 14 volts when it started and I had disconnected the other car. However after a minute or so the voltmeter would drop to nothing then the car would run very rough, like it was on 4 cylinders then die.

Its definately ignition related as the longer I left the other car attached the longer the stag would run and it would run as long as the other car was attached.

I had recetly replaced the alternator as my last one was shot and the ignition light was on.If I remember correctly there's 2 types, I replaced the earlier type for the later type, cant remember the codes, I think i replaced a 11 with an 18 if that makes sense? When I replaced it I put a voltmeter across the battery and it was reading about 12.5v which I thought was low but it was running fine and I had a wedding to get to so forgot about it.

Does it sound like a problem with my wiring or a problem with the replacement alternator. I'm not much good with electrics so could be my wiring. I remember being confused as I think I had 4 wires and 3 connection points on the alternator.

Appologies for the essay but wanted to put down all the info. Thanks for reading.

H

[sax player]

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Harve Check your battery first.

Put it on charge for 24hours, then leave it for a couple of hours, you should then be reading between 13.5 and 14volts. Connect it to the car and crank the engine over with the ignition lead off. It should be able to crank ( depending on size for a good 3 min) If its seconds check the voltage again. If its less then 12 the battery is knackered.

Shaun.

[Harve]

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Had thought battery, I think the battery was replaced by the last owner last year. Will give that a go but have had to leave car at my parents over an hour away so may take a while to get this sorted. Doh!

[stagstr]

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Hi Harve,

Have to agree with Shaun that the battery is the easiest to check and if you can't do it yourself then your friendly Battery Suppier will do it for you for free.

However, if the alternator is charging OK then by removing the jump start your car should still run off its own alternator - it is not dependant on the battery once it's going.

So it sounds to me as if your new alternator is goosed or wired up incorrectly and not charging the battery.

If you have indeed replaced an '11 for an 18' then it sounds as if you have a Mk1 car with a Mk1 alternator (11AC). You have replaced it with an 18ACR which is a MK2 alternator. The two are not directly interchangeable as your car has half its alternator control and relay gubbins on the suspension turret in the engine bay, whereas the 18ACR has it all inside the alternator. The Mk2 alternator can be fitted to a Mk1 by rewiring and bypassing the relay and control box, but did you do that?

Ray

[Harve]

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Hi there,

Yes my car is a mk1 but has had a mk2 engine fitted (its a bit of a mishmash of mk1 and mk2 bits). I was wrong when I said I replaced an 11acr with an 18acr, I forgot - that was what I was expecting to do when I bought the kit as it still had all the ancillaries on the offside suspension turret.

However when I removed the old one it was the 18acr alternator, the anciliaries had already been disconnected. However what I got confused about was that the connections on the back of the new alternator were slightly different to the old one. THe new one had a black plastic connector that I had to wire up boforeattaching itto the alternator where as the old one had terminals directly on the alternator casing if that makes sense.

Does anyone have a wiring diagram of the correct way to wire 18 alternator. Its annoying not having the car here to work on. Hey ho, it raining so wouldn't be able to use it at the moment anyway.

Thanks for your help guys!

[stagstr]

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Harve,

Sorry, my diagrams are in the full ROM, unable to copy and scan.

But if you go to Page 200 of the Technical Reprints section of this SOC website (members area) you will find an article on how to install an 18ACR in a Mk1. When I read it, it's as clear as mud, but if you have a Mk1 in front of you perhaps it makes sense. I hope so.

Ray