MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

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 Midget and Sprite Technical - Resurrection and a few issues

I last ran my '67 midget in September of 2005, and at that point the brakes worked but the lights didn't and the ignition light was on. Luckily I made it home from the ABFM. I parked the car and time has continued to roll along, the kids are older and I now have some time to tinker. Last weekend I replaced the older Facet fuel pump with a newer model I had be hauling around in my future parts bin for nearly a decade. The car now starts and runs, but of course the ignition light and brake lights still don't work.
So, could the brake lights be as easy as swapping out the old inline switch? or could it be associated with the ignition light being on? My headlights do work, a bit dim though. I was too bright to tell if the indicators worked. I'm thinking it's the charging system, but I've been out of the Lucas mode of thought for a while and could use a bit of help, ideas from the board, &/or a refresher course.
Many thanks.
Kerry Cooper

ignition light on means no charging!
so check the voltage on the batery with a running engine should be something like 14 volts

you can try an short the brake light circuit with a screwdriver over both contacts on the pressure switch
Onno Könemann

I put a relay switch in my midget after replacing three brake light switches. They seem to burn out withe current needed to run the brake lights. No problems since the relay takes the heavy current, and the brake light switch only has to activate the relay. I have them on my MGA and TD too.
Good luck steve
S E Bryan

no problem here with the original switch.....
Onno Könemann

..same here. With 25W bulbs the brakes should take around 4A, which should be within the capability of the switch.

A
Anthony Cutler

Here's what I tried last weekend:
Hooked up the charger to the battery cables/battery for nearly 4 hours on low setting. Unhooked charger and turned key, nothing happened, the fuel pump wouldn't even click for me, the gauges did move though.
So back to charging, this time I connected the charger directly onto the terminals having disconnected a cable. Gave it an hour and then reconnected the ground and it started right up. The ignition light is still on of course.
I used a volt meter and checked the charge at the battery and got 10.5 V, that's way too low.

What would be a good test next?
Kerry Cooper

put in an new dynama or altenator
or make sure the regulator works

the regulator sometimes can do with a little tap from a big screw driver

and you probaly need a new batery as well
Onno Könemann

shotgun approach would work.
however the generator was new (rebuilt) when I parked the car, the regulator is about 10 years old, and the battery was also new when parked, though that was 4 years ago since I had a successful drive. Any test to narrow it down? My local British parts shop closed last year so it's a little slower to get bits.
ty
Kerry Cooper

Update #1:
Took the battery out and down to a shop for a test, of course it failed about 20 minutes into a cycle test. It was under warranty for another 4 years, but the shop I had gotten it at has gone bankrupt and is gone.
So new battery is in the car, but first i wanted to to test if any current was being drawn that I did know about. YES! With everything off there was a 0.6V current draw. My new question is: What could be doing this? Any ideas??
Kerry Cooper

i don't know and would just fit a master switch and don't care

but you can pull of the leads from the fuse boxe one by one and see what the meter says so you can narrow the circuit down.

the generator you can check by putting current on the big terminal
it should start turning (bit of the oposit of normal)then ad power to the smal contact and it should change speed

if the generator works the regulator is at fault
Onno Könemann

picky I know but you don't measure current draw in volts....
David (davidDOTsmithAT stonesDOTcom)

If your regulator was faulty, it might still be sending current down the field coil when ignition/engine off (as if it were charging. Or maybe bootlight is on when bootlid closed (drill a hole in the bootlid so you can check - only kidding ;) ). (Boot = trunk)

David - you are being picky this morning. No meter really measures volts anyway - they all measure current. It's just that some meters have high series resistor that reduces the current to very low level, and then we call it volts...

A
Anthony Cutler

a drilled hole is ofyten to small to get a good look
you'd beter get the grinder out :P
Onno Könemann

It's a US '67, no boot light, no map light. Really not much light at all, most of the gauges don't have lights that work either. I'll test for amp draw for you. I'll give the fuse box a test too, there are only 2 circuits so that would be fast. I've wondered about the regulator not tripping the correct way and letting current flow back out. More to follow.
Kerry Cooper

Did some tests yesterday.

I opened the regulator cover and noticed some copper corrosion on the outer top coil, likely not a good thing.

Tested the fuse box, and no draw through it.

I tried to test the generator while the engine was running to check for voltage from it's two terminals, none (well a few mVolts).

Also noticed the F terminal on the generator can be moved in and out about an 1/8 of an inch, is this normal??

Tested the draw from the battery again while engine and key off, and found the same .6V draw. Then tested the A and A1 off of the regulator to ground while all off and got a similar though smaller draw of current. Interesting thing was that it was a pulse of low medium and higher.

Do you think the generator is bad, it's a rebuilt unit?
How about the regulator?

Anyone use one of the solid state regulators made by Bob Jeffers?
Kerry Cooper

take the generator off the car
and put power on it with jump wires to a good batery
first only the big terminal and the body and then if it spins ad the smal terminal (bit of jugeling with the wires) it should pick up speed

if it turns at speed than it is ok and the regulator is at fault!

but moving the terminal does not sound like a good thing...
Onno Könemann

did some testing as suggested by Onno. here are the results
on generator 1 (pretty rebuilt, from the car) : very slow tick over with the first connection, then a slight increase in speed with the second connection.
also tested generator 2 (junk i picked up from a swap meet for the pulley): it is screaming fast with the first connection then slows a little with the second
and then generator 3 (original from when i got the mg): also screaming fast with the first connection then a slower speed with the second.

i thought that it would speed up with the second wire hooked up. could all three be bad, just in different ways. i don't quite understand the smaller wire (field) and what it's use is.

seems the worse looking ones may be the better, do you agree?
Kerry Cooper

I Know this is a long shot but do you have a radio fitted? my battery ran down after a week then i discovered the radio was taking current even although it was switched off.
I Hamilton

Unfortunately I have no radio in the MG. This is my problem in the old Range Rover, I've installed a cut out on the battery to solve it's problem with the cd changer.

Any ideas on the generators? I'll get into it again soon.
Kerry Cooper

Well I've reinstalled the generator from the car (generator 3 from the tests above) and it works! The warning lamp is off and the turn indicators work very well. however i was told the break light do not light much. i'll have to get in and clean the contacts and see if that works or change the in-line pressure switch which will force me to change the fluid which could also be an issue with such a long storage time.
thanks thus far..
Kerry Cooper

This thread was discussed between 09/06/2009 and 27/07/2009

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.