More strange alternator happenings!

[DSL]

Update on voltage all over the place! Looks like a new alternator is required ☹️

 

Removed the alternator & found that the live feed was a little loose, so tightend it up & re-installed it fully expecting it to be sorted, wrong ☹️

 

On starting, the car voltage at tickover is a stable 12.3v with good idle, as soon as you rev it beyond 2000rpm voltage goes upto 14.4v & stays there even when returned to idle which has now gone lumpy. Turn it off & start again, does the same every time.

 

I take it the alternator output goes straight to the battery & that there is not a voltage regulator somewhere inline that could cause the same problem

 

Unfortunately whilst I had the alternator out of the car I did not take any numbers off it, so if anyone knows he details of what it is I would be greatful

 

Edited by - dsl on 4 Sep 2007 21:37:34

[rj]

Darren,

 

14.4v does not sound too bad to me. I think mine cuts off at 14.6v

 

Is the headlight flickering or stable? If not flickering you're probably OK.

 

I've got a spare on the shelf, I can look at the numbers tomorrow afternoon if no-one have given you the number before. Mind you, Caterham no longer stock the small alternator I've seen on a LHD R400. I had the big heavy lump, which failed after 2k miles; now I've got a Brise.

 

/regin

[Peter Carmichael]

Silly question, but is the ignition light coming on before you start the engine. This supplies the priming current to the field coils - no ignition light means the alternator has to self-energise the coils usually takes revving to 2000rpm to achieve this. Otherwise, when running, sounds like you have a functioning alternator.

[Jason Plato]

14.4 is normal @ 2000 rpm

 

I have 2 under my bench at home - I'll check the part numbers this evening - its a std rover 1997 rover 418 16v part as I recall.

 

but it sounds like the alternator is working OK at low revs.

 

lumpy idle is probably the cold start / warm up map needs minor tweeking - it was a pretty cold evening yesterday......

 

Taffia rear gunner

 

[DSL]

Peter, ign light is going on

 

RJ, lights are flickering whilst engine ticking over

 

Dave, the idle was good from start until you have reved beyond 2000rpm then goes lumpy as hell nearly stalling. If you then switch off & restart without reving up idle is stable as per normal, rev up & same thing happens again

 

What say you 🤔

[Peter Carmichael]

What say you

 

Your mapping is all to cock because the alternator was playing silly buggers when it was done.

 

Definitely get a laptop attached and see what it is doing at idle.

 

 

[DSL]

Peter, its a possibility. As I do recall the voltage doing strange things whilst I was running it in, before it went for the mapping session.

 

However, I drove it for 20-30 miles the day after it was mapped & it ran great, then all of a sudden would not take anything other than a trickle of throttle without shunting & shuddering, which would suggest to me that something has gone raving tonto

 

Can I just disconnect the alternator & try running the car off the battery only, will that work for a trial run to see if the alternator is causing the problem

[Peter Carmichael]

On a healthy battery you can get a couple of hours running, but keep it to a minimum as deep discharging of the batery will kill it.

 

What does the laptop say? First port of call should be to examine the ECU's behaviour directly.

[DSL]

Peter, I dont have a can lead on the car so can't take a peek. Disconnecting the alternator will tell me if its just that within 5 mins, so will give that a try

 

Is the best way to do that by removing the drive belt, or do you happen to know which live feed comes from the alternator

 

Edited by - DSL on 4 Sep 2007 09:50:06

[Jason Plato]

dont take the drive belt off - this will get tangled up with the dry sump belt

 

remove earth on the battery and then disconnect the feed to the alternator and wrap in duck tape to insulate andf tie wrap to secure.

 

I only get about 20 mins from a charged battery with no alternator - been there done that a few times of late

 

 

 

Taffia rear gunner

 

[Jason Plato]

The live feed is the big red fat fecker 😬

 

Taffia rear gunner

 

[DSL]

Cheers *thumbup*

[DSL]

Mmmm, the plot thickens ❗

 

Disconnected the alternator lead & made no difference

 

So set about disconnecting & reconnecting all the sensors. The one that connects onto the coil pack thingy does not actualy click into place & was easily dislodged, so pushed that down as hard as poss then started the car with success of sorts, idle now stable so taken for a good spanking, it ran without missing a beat for the 10 miles or so driven

 

Noted the voltage was still up & down but as it was causing no problems with the engine running I was not too bothered, when coming down the lane home at a steady 2000 ish rpm the volts dropped to 11.5 & 11.3 at tickover with the lights on. Then when reved up to 4000rpm the charging light comes on whilst showing 11.5v, then shot up to 14 odd volts & when returned to idle it now shows 13ish volts

 

I am rather confused, any ideas you K guru's please

[Peter Carmichael]

You don't need a K guru. You need an alternator that isn't broken. Your loose connection will have knacked the diodes/regulator. An alternator repairer type person will sort you out.

 

Edited by - Peter Carmichael on 4 Sep 2007 22:40:44

[DSL]

Thanks for your input Peter I will gladly buy a new alternator today to fix it, cause I'm begining to lose interest in it already

 

Which brings me back to my first question, do you know the model number of the R400 alternator at all

 

 

[Jason Plato]

As promised :

 

Magneti Marelli alternator with a sticker reading the following : 54022631 12V Type: A127-55

 

I bet if you take your alternator off you will also have a sticker on it [scratches chin] 🤔

 

I am slightly concerned that this was for a EU2 engine and your R400 will be EU3, I dotn know if there was any difference between the 2.

 

motor factors will be able to recognise this part number ( or they did for me)

 

I recall a recon was a hefty £160 odd pound 😳

 

Dave

 

here is C7 TOP

Taffia rear gunner

 

[DSL]

Cheers DJ, best bet is to whip it out tonight then I guess & check the numbers first *thumbup*