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MG MGA - Starter Solenoid

I'm having trouble with the solenoid. Sometimes it works, sometimes not.

I thought at first the cable had stretched, and that the cockpit starter knob wasn't pulling the rod far enough to make contact, but I now can't start it by getting under the bonnet and pulling the rod full travel.

And then suddenly I can, with the rod moving only about half travel.

Any ideas?
Nick and Cherry Scoop

Nick

They are notorious for burning out, especially some of the modern ones. Time for a replacement. They take a heavy load. Have a look at one of mine that I took apart.

I don't have that issue now as I fitted a pre-engaged starter which resulted in the switch taking a much smaller load, but that is an expensive option if the starter motor itself is causing you no issues.

Steve


Steve Gyles

Nick

I did have a spare one, somewhere.
I'll have a look for it.
Dave O'Neill 2

That's very kind of you, Dave.

As a matter of interest, I've just been into town - three restarts and all trouble-free.

But it's not to do with warmth, or use. A few weeks ago I was at Brightwells Classic Auction, parked in a prominent position opposite the cafe, paintwork gleaming, and I simply couldn't make the solenoid work - had to get the starting handle out.

Nice pictures, Steve. Thanks for the reassurance. Are the contact plates sprung?
Nick and Cherry Scoop

Nick

If I recall correctly, that copper disc in my photo is free to spin on the pull shaft, so it is quite possible that it occasionally revolves the odd few degrees to bring less burnt parts of the disc into contact with the copper contact plates.

The contact plates I don't think are sprung, but there is a spring on the pull shaft to help break contact after use.

Steve
Steve Gyles

Is it definitely the solenoid?
Have you tried bridging across it?
Dave O'Neill 2

There is some confusion here. As far as I know, and from what I can see from Steve's photo, it is NOT a solenoid but a simple but heavy duty switch.

Also be careful bridging it out due to current involved (approx 130 amps I believe). Must use battery lead quality cable or good battery jump leads. I am not sure how you are thinking of switching it, but whatever I would make sure you are in a position to instantly disconnect battery. Things could get very hot very quickly if you get this wrong. Personally like Dave I would probably try it but!!

Paul
Paul Dean

Paul, you're quite right of course, but I didn't know what to call it.

Ah yes - instantly disconnect battery in an MGA . . . . . . tricky.

It's why I check the ignition timing so infrequently, too.
Nick and Cherry Scoop

Sounds like a loose connection to the starter motor. Exactly the same thing happened to me a couple of weeks ago.
N McG

Nick

Going back to your original fault, i.e. intermittent starting problem, reminds me of a problem I had in summer 1970!. It could just be your problem.

For reasons I can't remember I had the engine out overnight the night before heading to France. Got to ferry and it wouldn't start, hence got pushed on and off ferry. Took it to a garage in Dieppe who claimed to have fixed it and the car certainly then started during drive to Paris, then problem started again intermittently. Tried to get exchange unit in Paris, as you could at that time in UK, but only new very expensive units available at BMC dealer in Paris. My poor girlfriend of a few months carried on pushing as I was asthmatic (she still loves the A, and me I hope). On that day the starter in a bag went around many of tourist attractions including Notre Dame!

Stopped at small village garage south of Paris. Mechanic grunted, dismantled starter and problem was clear. There is a spiral shaped flat rod inside that carries the current from terminal to other end of starter and this, while still being in place, had sheared (perhaps by me over tightening as I was very tired when I put engine back in). He welded/soldered/brazed a tube around the rod and starter is still on car 44 years later.

Its a long shot but it is just possible you have same problem and switch is fine. You could try giving starter a bash while you starting but failing to start.

Paul
Paul Dean

I have had the same problems with my MGA's (coupe and roadster). I hid a new switch under the heater trunking and overcame the problem. The original switch (pulled to pieces and cleaned) just sends the current to the new one (to turn it on).
Barry Bahnisch

N McG - good idea, but no - the connection is solid.

Paul - good one - I almost want to dismantle the starter motor this afternoon to have a look, but the MGA is my only transport at the moment. Two quibbles about your story :- (i) how come you were able to wrestle the engine out but couldn't push, and (ii) what about the starting handle?

Barry - good solution. Where did the new switch come from?
Nick and Cherry Scoop

Nick

Asthma - It would be really bad for a few days then fine for a while. I think it was the vegetation in the Paris Bois de Boulogne camp site that caused that attack. I even did a full days work between the engine 'out and in' over Thursday night, finished the car Friday evening and drove overnight Birmingham to Newhaven stopping for a middle of the night coffee with colleague who were working all night in central London.

I don't think my girlfriend could have used the handle and I wasn't up to it. I guess we took advantages of any slight downhill slopes!

Later the fanbelt broke in French Riviera at start of holiday weekend. Did numerous Alpine passes though in my £100 coupe.

Paul
Paul Dean

Paul - I did not know asthma could knock you over like that. I suppose most of us with (touch wood) reasonable health don't really have a clue about the things that afflict our pals.

At the moment I'm going strongly with Steve's diagnosis. To begin with, I was pulling that knob out as far as I could, and holding it there, before repeating. No joy.

Now, I'm giving it a quick pull and letting it go back straight away - while I imagine the disc gaily turning - and the starter motor's working on about the third pull. I shall see about getting a new one, and I'll certainly prise the old one apart for post-mortem.

Not many MGAs about at the moment, are there? Being close to Brightwells, and having sold a Sprite there a year ago, I go to all the classic auctions, and I haven't seen one for ages. Plenty of Triumphs, MGBs and Cs, even Alpines, but no As.
Nick and Cherry Scoop

Paul, I had my starter apart for overhaul recently, and that flat rod is not supposed to be spiral shape! So yeah, you really did over tighten it. Good trick to know about soldering a tube over it though.

-Del
Rawlins

This thread was discussed between 19/06/2014 and 22/06/2014

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