MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - Alternator Problems

Hey you lot, my car is back together with the 135 head...........and the alternator has packed up,

1. I got a new one and fitted it,

2. Still no charge at the battery

3. multimeter reads 2.7v across the alternator terminals,

Anyone any ideas??

Is it anything to do with the third wire on the alt wiring loom, its red and has a female blade plug on the end of it, doesnt seem to go anywhere??? and wasnt on the old one either???

Rick
R P Earle

Hi Rick,

Just how much have you been swearing..? ;o)

IIRC I've only ever removed and re-fitted two wires when swapping alternators, so I can't see it being that 3rd wire.

If the alternator isn't producing 12v or thereabouts, that suggests the new alternator isn't functioning correctly.
Mike Hankin

Mike I only swore a few times..................before i stopped counting!!!!!!

Got the car to a good 'Driving Road' and the ABS light came on, wierd, i thought to myself, then the EPAS light and then the SRS light and then the car stopped!!!! BUT Still no battery light?

The battery light has come back to life today and is on, but stil no charge even after the alternator has been changed????

PLUS my stupid new QH water pump is leaking round the seal i think??!!!!
R P Earle

Earth strap on the engine failing perhaps, preventing the alternator from having a ground? There's a root cause for all these symptoms, except possibly the water pump - that doesn't sound electrical...
Mike Hankin

Oh fun and games Rick :o(

A duff alternator perhaps?
Rob Bell

Anyone know where the earth strap on the engine is, i had a look but couldn't find it...................

Oh and i tried earthing the block to the body with a jump lead and it didn't make any difference........(trick learnt from owning GTE's over the years earth leads always went!!!)
R P Earle

Add your own one back to the battery from the alternator itself.
C.R.B. Simeon

Rick,
Sorry, called away. I don't propose this as the solution to all of your current problems but it cannot hurt. I fitted a decent return between the alternator mounting bracket and the battery negative it may help with other issues(esp corrosion). The explanation for this mod is a 'preferential return path' for current.
Choose your own route from battery to alternator but the starter feed is a good route for most of it. You want wire of similar characteristic to the starter feed i.e. approx 7mm dia or better. Use 4-5 m of braided multistrand insulated earth wire. A piece of mild steel fencing wire would do exactly the same job but look orrible and be heavier!
I would leave the original weedy straps in place as they wont do any harm. Sorry you have had two such major problems - Good Luck.
Charles
C.R.B. Simeon

Is the battery light coming on when the engine is not running ? This is connected in series with the "third wire" of the alternator. It delivers a magnetical field in the alternator which it needs to "start up" If it doen't have this field there could still be some maganatism in it left form the previous run, enough to get it started again.
Sander

Im very happy

Purple Haze is back on form, this is how it went,

1)got up and swore at the car several times, after fitting yet another alt and still only 2.7v out of it, rang adrian and came up with a few ideas!

2)connected two jump leads, ran them from the + on the alt to the battery +, Alt worked fine and the battery was charging at 14v,

3)Tried to trace the wire back to source in the engine bay, Li pulled a wire on the starter by chance it had broken!!!!,

4)Sometime before i had the car, the terminal which connects the main live from the alt to the starter sol. had broken off??? Some bright spark re-connected it with a 5amp blue crimp ring connector using 1/4 of the core cable, hence my old starter blew and so did the connector!!!!

5) a few hours later, new battery cable run from the starter to the alt and all is well!!!

6)tightened the bolts on the water pump and that stopped the leak!!!

Rick's now all happy and has a car he can pose in again!!!!


Thanks for all your advce guys and gals as always!!!
R P Earle

Great result :oD

Now, how does the car feel on those 135 cams? :o)
Rob Bell

NICE!!!!!!

Sooooo much difference, to be honest I wasn't hoping for much in the way of power difference, but was pleasantly surprised, car feels a lot nicer to drive and is a hell of a lot smoother and makes a gorgeous roar undder heavy throttle now!!!!

Not pushing it too hard for a few miles yet as the head is brand new not recon so am treating it with a bit of respect, plus im in fear of something else breaking!!!

Rick
R P Earle

Well, +15bhp was always going to make itself felt - plus you'll find some real energy all the way up to the red line :o)

Enjoy - and I hope that this is it for problems on your car for the time being!
Rob Bell

This thread was discussed between 12/05/2006 and 14/05/2006

MG MGF Technical index

This thread is from the archives. Join the live MG MGF Technical BBS now