I'm an extremely happy new MGF owner and have thus far loved the first 1500 miles with my new toy.
Having managed to correct the EPAS issue via this forum thanks to the handy guide and conduct some other tweaks and maintenance I'm currently flummoxed by the latest issue I'm having.
Everytime I start the car the battery Warning Light doesn't go off until 5 or so mins into the drive at which point it seems to fade and or flicker seemingly in tune with acceleration/revs before finally disappearing and failing to reappear for the remainder of the drive.
The previous owner had the alternator replaced with a newer '3 wire' model less than 6 months ago and this issue wasn't a problem for the first 1000 miles of my ownership (from 70k miles). I have checked and ensure connections are good to the alternator (initially thinking it was a dodgy connection) and the belt looks to be correctly tensioned and in good condition. When idling the voltage across the battery is just under 14V and I've also replaced the battery as well with a Varta Silver thinking this was the issue (previous battery was several years old).
I'm now at the point where I think the issue lies with the battery Warning Light circuit but am clueless where to go next. Would anyone be able to suggest where my next Avenue of troubleshooting might lie?
This forums been a fantastic resource thus far so in any case thankyou from a recent lurker!
Hello Jack,
Personally I wouldn’t discount the alternator as being the suspect here. It is not uncommon for aftermarket ones to be of dubious lasting quality. 14v output seems a little bit low to me, but I’m sure other forum members will come along with additional advice.
Do you know if the car been started using jump leads since the alternator has been changed? If so, any chance the leads may have been temporarily connected the wrong way around?
Kind regards,
Austin.
Thanks for your reply. I was hoping I'd get away without having to touch the alternator but it seems that might be the next line of inquiry...! Come to think of it I wasn't able to figure out what brand it was under closer inspection as it just looked generic (like this one http://www.incony.org/webpics/MGF Alternator1.jpg).
In my ownership I haven't had to jump the vehicle (and it's started every time). However, couldn't comment on previous owner as they continued to drive the vehicle for a few months after the alternator replacement. I'm guessing this can mess up the alternator if the polarity is reversed?
Are there any other checks I can do to better confirm the alternator is knackered or is it a case of just replacing it with one of known quality? The only other thought that springs to mind is that I noticed the splash guard across the rear drivers wheel Arch is missing and this issue seemed to present itself after a particularly wet weekend a few weeks ago so potentially this could be the root cause...and I should look to replace this as well?
Thanks. Hoping this doesn't start turning into a money pit as I'm quite fond of the car so far!
Hello,
If this was mine, I would be tracing a trusted local auto electrician and getting them to check the alternator output. A simple test, and indeed most garages should be able to do this for you, but you will need the services of an auto electrician should the alternator be proved not to be up to par, so maybe better to go down this road first.
The alternator lives in an inhospitable location and using the car in rainy conditions without the plastic splash shield is not best possible practice, so I would be looking for one of these - and it’s fixings.
The alternator should be repairable in the hands of a good auto electrician, so it might be worth first checking with whoever you chose as to whether they would repair it rather than replace it if it is at fault. Find an AE who is prepared to repair it.
Kind regards,
Austin .
As what others have said here get it checked out first. A simple multi meter on the battery can be used to confirm if the alternator is functioning correctly. When the engine is not running the voltage should be around 12v, when the engine is running it should be between 13.5v to 14.8v dependent on the speed of the engine.
By personal experience I stay away from rebuilt alternators. A lot of the times the diode pack/dc rectifier on the rear of the alternator are usually cheap ones from China that rarely last more than 12 months. I had three rebuilt alternators across my old MG ZR and my current Rover 25 none of them lasted past six months with one failing within a week of installation.
I purchased a brand new Lucas one and its been on the car for over three years now with no issue.
Rebuilt alternators are false economy as far as i'm concerned, i would rather get one from the scrap yard than buy a rebuilt one.
That's a very strange point of view, we have a local auto electrical shop which if you take in an alternator will change the diode pack (normal unit that fails) put in new bushes & new bearings, clean it all up including a spray paint, they offer a 2 year warranty & charge around £50 for our Rav4 alternator, against £135 off Fleecebay or Eurocarparts, didn't dare ring Toyota. I'd rather have that than some random one in a scrapyard.
According to the OP’s original post, the battery has recently been replaced with a new Varta one, also the charge light takes a long time to go out - and flickers.
I would still be suspecting the alternator, and getting its output checked as first priority.
Thanks everyone for the replies. Strangely enough I had no issues driving around like this for a number of weeks but took the plunge in replacing the alternator and belt myself with a new like for like replacement from eBay. Was about £100 all in and following this mornings drive to work the battery warning light has now disappeared! Fell fairly chuffed for having managed it myself in 4 hours...thats a Saturday morning I could have back but...touch wood it should stay that way. My next port of call was going to be checking the connections and Earth straps around the entire circuit which I wasn't feeling particularly enthusiastic about as everything on this car seems a bigger to get to!
Perhaps it me, but am I reading this as ‘.... the battery light went out during the journey’ ? -or did the light go out immediately on start up following fitting the new alternator?
Austin you're quite right. Light went out during the journey. Not immediately upon starting up. Tonight when leaving work she wouldn't start either. I got the dreaded machine gun clicking sound and a flat battery.
I feel as if I'm at my wit's end a bit here. Going to get it recovered and to a garage tomorrow. I just want a reliable car ?.
OK, so the light didn’t go out immediately - bad sign to start off with.
EBay and £100 alternators? Um!
I would say the way forward is :-
(1) Get the alternator output checked. ( don’t assume new equals serviceable).
(2) Charge the battery overnight then get its efficiency checked.
(3) Check all battery leads and connections, and all main earthing connectors.
Right so
1. I've checked the alternator output directly at the alt (+ve to engine block) and across this battery terminals and am getting 14.5V DC with the engine running.
2. Charged the battery up overnight and getting a healthy 12.6V. It was just under 11V when I took it out so definitely dead!
3. I've measured for continuity and voltage drop across the whole circuit using the wiring diagrams and checking all the earth connections, cabling to the starter motor across the starter motor and to the alternator. This highlighted that the battery warning light bulb looks to have blown. Starting the car once the battery was full confirmed this as true as it doesn't light with ignition on or as the engine is started. I've been reading up on this and wondered if this could be causing the alternator not to 'self excite' on shorter less spirited drives and thus the battery depleting itself over several short trips.
It looks like I need a capless 1.2W 286 instrument panel light bulb from Halfords for this and will try replacing and checking that tomorrow. Will see how I get on with that!
Narrowing this down now as not the bulb but in fact looks as if the smaller cable from the alternator that completes that circuit is damaged between the alternator and the connection point at the back left of the engine bay you can access via the boot. On inspection the engine wiring loom from the alternator passes under the engine and is tucked into the subframe on the way to the starter motor. It's in fairly poor health and k suspect there's a damaged connection in amongst this loom that is causing my issue.
Going to test this at the weekend by hooking it directly from the connection to the alternator and will see where I get to!
If an alternator doesnt self-excite- then it will not produce an output. About 15 years ago my son had an Escort that wouldn't see- excite- so I stabbed the windings with 12v and it remained excited, but obviously wouldnt when re-started. So, I fitted a cable from the starter-motor live solonoid switch via an 100amp diode and connected it to the field. The idea being that as the engine turned over- the field was energised. It worked a treat.- I simply didnt have the money back then to buy him a new alternator! He sold the car 3 years later with my mod still in place.
Spot on Pat, I've learnt a lot about car electrics these past few weeks but this looks to be the root cause. I never could find the actual break point as likely buried in the wiring harness somewhere and I didn't want to risk messing about with that too much but suspect that it's been failing for a number of months particularly in the wet and hence it being an intermittent fault.
Managed to narrow it down to the cable I'd described, cut the old cable at either end and isolated with electrical tape. Sleeved some 1mm cable and used a butt connector to fix it to the exposed end by the engine relays in the boot routing it through the engine bay with cable ties to a ring connector at the alternator. Fiddly job and about £10 worth of bits but after charging the battery the car starts and the alternator is now charging!
Will piece it all back together tonight and get back on the road all going well.
Here's to making it through the MOT in March...
Thanks to everyone that helped out!
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