Deb

Had my alternator repaired and too much time has elapsed since removeal of same. Alt. shop insists that the alt itself provides ground by its' attachment to engine block and threfore the other wire "green" goes to "neg". Which I did but not sure that is correct and befor I tear it appart again - looking for real story. Here are a few readings with it in this setup
-Batt at rest -12.84 vlts
- " key in #1 position - 12.64
- " " " #2 " - 12.43
- " @ 800 RPM - 12.27
- " @ 900 RPM - 13.92
The latter is after blipping the accelerator which causes the pod voltmeter to jump up to a 14 vlt reading.
Is this because of the ground/(-) wire on the wrong terminal??

jim912928

Hi Deb, I would like to know what can be done to fix that blip the accelerator and the voltmeter jumps. Mine just started doing it the past year. So, I hope someone has the answer!

On a side note, nice to see someone who also likes the old english British Leyland cars! Don't have any anymore, but I've gone through a TR6, GT6 and a TR7...wish I still had the TR6 (was red, red factory hardtop, redline michilens!). My dad just sold his 74 MGB with about 150k miles on it and still has a 57 TR3. The GT's are getting rarer and rarer...keep your hands on it!

Deb

Yes, I get alot of interest lately just parking the MGB GT on a downtown street. I think that the convertibles are still more in demand but I bought this 72' about 8 yrs ago for $2500.00 from someone who was stuck for cash, I put brake shoes all round but that has been my total investment to date. So easy to work on compared to the 928 but my Yanmar diesel is also a great engine for access and simplicity.

Deb

I also had access to an Austin Healy 3000 which I passed up about 25 yrs ago, now a good one is about $45,000.00, too late now given the price but they are a classic!

Tony

My first car and the one i learned to drive in was a 72 MGB GT. In that blaze orange color as well. I will definitly own one again...just a fun little car and a classic

John Struthers

Deb,
Unsure of the 84'MY, but on my 82' I believe the green wire runs around the front of the oil pan at the seam lip to mid engine and for some reason is grounded to a thru bolt/nut combo.
Sorry I can't remember -though I think I did- if I went ahead and and hooked up to neg. . However, why would the darn wire go to ground in a separate location but essentially to the block?
Could you look if there is a gap in that orange bundle cover to see if your green wire goes to the front oil pan seam as well?
PS
My neighbor, a basically evil person has a little, white/black top convertible
MGB -late 60's early 70's from the look of it-
There was a time... unfortunately, at 6'2" I could not easily fit in MG's MGB's or those cute little green Sprites

Deb

Tony, odd that you should mention "that blaze orange colour", that's what mine is also. When the PO described the colour over the phone prior to my purchase I thought - what an ugly colour - and thot twice about even going to look at it, I soon go to like the colour, it probably works OK with a small car like the MG.

Deb

John, the green wire comes out of that bundle of wire in the orange sheath with the larger + wire, I can't determine where it goes except along with the others in the bundle - I'll look again tomorrow and get back to you.

User 4221

The green wire that John S. refers to goes to the oil level switch.
The wire that goes to "Neg" is the alternator field exciter ckt. It should be a 16ga. blue wire.

If you want to ohm out the blue wire to be sure, it connects to pin 1 on the 14 pin connector that resides behind the jump start terminal.

HTH,
Scott

John Struthers

Scott,
Oil level switch?
I know where the oil pressure sending unit is but am at a loss to oil level switch.
If it exist's where does it make an input and if level is low where is the warn?
Jesus! Something electrical I haven't been hammered with ... yet!

User 4221

John,
The oil level switch resides on the in front of the block on top of the oil pan. You will know when it becomes unhappy because the "!" light flashes violently and scares the heck out of you.

Here's the signal path in detail:
Oil level switch - 16ga. blue/green - Terminal 3 of 14 pin connector - Fuse board, Connector P, positon 3 (P3) - Fuse board, Connector G, positon 3 (G3) - Central warning unit.

The wiring diagram shows the switch being normally closed. If I understand this correctly, then it should Ohm out to 0 if all is well. However, you should verify this as I could be wrong in my interpretation.

HTH,
Scott