Hi all. My 1996 MGF has an alternator issue (again) last year the diode set was replaced and its been running fine since then. last week battery ran flat and car stopped, not charging. When tested with voltmeter, battery shows 11.5vdc when started, idling and revved. No charge from alternator.
when i measured voltage at alternator positive terminal it reads 14.5vdc. Ive inspected terminals and they seem OK.
Ive googled a lot on this hoping to find answers. there are a lot of posts on the MGTF and the "alternator fuse" but it seems, no such animal on the Mk1 MGF. Ive yet to check the connection from alternator to starter motor.
Does the reading of 14.5vdc at the alternator definitely mean its working and volts not getting to battery? Or is it still possible that there is another explanation?
MGF Alternator problem
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Not many rules really, this board being aimed at technical issues, it shouldn't fall foul (hopefully) of some of the more personal issues that can affect forums.
Rule 1 - Is that you need to think very carefully before posting anything technical or asking anything technical relating to the security system of the car - See 'Security Issues' sticky for more info.
Rule 2 - We (MGF Register) do not support copyright infringement and therefore references to CD ROM, PDF versions or paper copies of the workshop manual (for instance) should not be posted on the forum. We don't want to get into trouble and we'd rather sell you a genuine hard copy through our Regalia shop anyway!
Because advice is honestly and freely given in this technical section, much of it will be amateur experienced based, so any information is given in good faith and is not guaranteed as correct.
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DaveInBorneo
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Chris Tideswell
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Re: MGF Alternator problem
With a voltage drop of 3 volts I would be expecting something along the line to be getting hot! I would therefore think that the charging circuit is open so what you are seeing is just the battery voltage across the battery and the alternator not seeing any load at all. I think that this is still the case for early F's, the main charging circuit is protected by a fuse, this is located on the boot bulkhead in the engine bay. So remove the grill and look directly down towards the centre line of the car.
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DaveInBorneo
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Re: MGF Alternator problem
Strange. I looked at the alternator again today ready to check connections etc. Before I disconnected the battery I started the engine again, no battery light! So checked the voltage at the battery and it was 13.8vdc. Checked at the alternator positive terminal and the same. So the alternator is charging again. It seems to have fixed itself.
What I did notice though was when I revved the engine above idle there was no change in the voltage. Also when revved I detected a kind of burning odour. If Im to mistaken its the kind of odour from brushes, a bit like a drill motor that is overheating. I thought it might be my imagination so I repeated a few times, shutting off engine, idling.... no smell.... revved to 2 or 3 thousand RPM and a distinct overheating electrical smell.
Would I be correct in diagnosing that the intermittent problem with alternator in this case could be brushes need replacing? Or possibly a diode overheating in the alternator?
PS Ive looked everywhere for that alternator fuse in the boot bulkhead. Is anyone who has an MGF early model able to post a photo showing location and what it looks like? I really can't see anything that looks like a fuse in this area.
What I did notice though was when I revved the engine above idle there was no change in the voltage. Also when revved I detected a kind of burning odour. If Im to mistaken its the kind of odour from brushes, a bit like a drill motor that is overheating. I thought it might be my imagination so I repeated a few times, shutting off engine, idling.... no smell.... revved to 2 or 3 thousand RPM and a distinct overheating electrical smell.
Would I be correct in diagnosing that the intermittent problem with alternator in this case could be brushes need replacing? Or possibly a diode overheating in the alternator?
PS Ive looked everywhere for that alternator fuse in the boot bulkhead. Is anyone who has an MGF early model able to post a photo showing location and what it looks like? I really can't see anything that looks like a fuse in this area.
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talkingcars
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Re: MGF Alternator problem
As per facebook - the MGF doesn't have this fuse.DaveInBorneo wrote:PS Ive looked everywhere for that alternator fuse in the boot bulkhead. Is anyone who has an MGF early model able to post a photo showing location and what it looks like? I really can't see anything that looks like a fuse in this area.
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