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 MGB Technical - Turn the key and -- click.

I'm very new to MGB's (just bought my first one in October) and rather new to auto mechanics in general. I've put my MGB (1979) up for the winter, but I went out to start it today, and, when I turned the key, it just clicked. Not wanting to neglect the problem, I set about trying to fix it. First, I had a friend try to jump it. No luck -- it still just clicked.

Now, it's got an older points-based ignition on it, presumably installed by a previous owner, and I was planning on changing it to an electronic ignition this spring, but I kind of wanted to wait until spring, as I a) don't really have the cash and b) don't have a heated garage. So I'd like to replace as little as possible to get it running again.

I know this is a pretty sketchy description, but, like I said, I'm new to this. Could it be that the coil is toast? I've had starters go out on me before on cars with electronic ignition, but they generally went out with a grinding crunch. That, and I'm not even sure that there is a starter-equivalent in a points-based ignition.

Basically, any tips you can give me for diagnosing the problem would be greatly appreciated. Thanks a ton.

As a postscript, if there's anyone out there from the Lincoln, NE MGB owner's club, I'd love to hear from you. I tried contacting the club but never heard back. Thanks.
Chris St. Pierre

Have you checked your battery cables? Are your terminals corroded?

TheMiz

Hi, Chris - two completely different issues regarding the starter circuit and the ignition circuit.

The 'clicking' you describe is symptomatic of a bad starter solenoid, either one built onto the starter, or separate, but let's check one other thing first.

As the Miz sez, first step is to assure yourself of good battery power, and the easiest way to do this is to turn on your headlights, and try and start the car. If the lights are good and bright, and only dim slightly when you hit the starter switch, then the battery and cables are probably OK.

If the dim significantly, or go out, you've either got a low battery, or a starter drive that's stuck to the flywheel (relatively rare, but it happens). A couple of taps with a hammer on the starter will usually free that one up, or turn the square shaft that protrudes from the back of the starter with a wrench.

More likely, you've got a bad starter solenoid that passes the battery voltage to the starter. Here's a good site to look at:

http://www.keystonemg.com/tech/

Check out the part labeled "Lucas Fault Diagnosis", pages 10 thru 14. Cheers - - Alec
Alec Darnall

Chris:

The first place that I'd look would be battery connections (expecially negative) Be sure to CLEAN all connections. The fact that a jump produced the same results should indicate either a bad connection or the solenoid. The bad connection is the most basic and easiest to cope with.

Jack
JACK

Wow, thanks for the feedback.

The battery connections were solid, but the positive was a little corroded. I'll clean them both off tomorrow and recheck.

One thing I noticed was that the interior light was significantly brighter when the jumper cables were connected. I'll do the headlight test tomorrow as well.

Alec--

I've actually got a copy of Lucas Fault Diagnosis on my desk. It'll be some lovely light reading before bed, I think. Thanks very much.

One final thing: everyone mentioned the solenoid, but Moss only lists solenoids for cars from 62-67. Or is that something that would have been retrofitted along with the rest of the points-based ignition?
Chris St. Pierre

The starter has the solenoid built in on the later models (pre-engaged starter). It looks like a small coke can on the side of the starter. All of the wiring (including the main live feed for the car from the battery) attaches to the end of it. The solenoid has a plunger that is pushed out through the magic of electric trickery to get things moving when the starter is needed. The click indicates that some power is getting there but it's not doing the job. A sharp tap with an "Abingdon spanner" may free things if you are lucky and the pluger is stuck, but your best bet is to go to the Jump To dropdown list at the top of this page and select MG Electrical Problems & Solutions, or try http://www.mgb-stuff.org.uk/. Both are much more digestible than most manuals, with step by step troubleshooting. By the way, welcome to MGs. You'll love them, even when they don't behave perfectly.
Steve Postins

It's cold--the car's been sitting for a while--you may just have an old and tired battery.
R. L Carleen

My roadster seems to regualrly suffer from corroded battery terminals but a good covering of vaseline seems to help. However, the stuck starter as Alec suggested is also worth checking. Mine does this regularly but can be sorted by putting the car in first gear and then rocking the car gently. Always starts first time after doing that. One day I'll sort it properly; before it jams completely on a cold wet winters day.
steve
S Coulson

Chris,

The original "helmet" style battery connections can SEEM solid/tight when they are not. Try tapping them gently with an insulated hammer, even though they appear tightly screwed on. Eventually replaced my connectors with the more convincing "clamp" type due to intermittent loss of all electrics/starting.
On the other hand as RL says your battery could be at fault---check that its charging.

Bumpkin.
Bumpkin

I'd have said the jumpstart has ruled out the battery if the cables were well connected . Just a thought though, was the donor car running when you attempted the jump? Although you can get away with it on many cars, I've always found my both Bs need the extra power to get them turning.
Steve Postins

A dead cell in the battery will not let you jump start, as the battery draws all the current.
R. L Carleen

The first diagnostic is too be aware what happens to your ignition warning light or interior light when turning the key to start. They will dim slightly when cranking normally, but if they dim *greatly* when you just get the click then that signifies a bad battery or bad heavy current cable connections i.e. the load of the motor is killing the voltage. A jammed starter will cause much the same effect, usually giving a little movement of the gear lever, but I have only ever known that happen with the older inertia starters, not the later pre-engaged. If the lights do nothing when you get the click then it is a solenoid or starter problem i.e. the heavy load of the motor is not being connected to the battery.

Rocking in 4th gear, not 1st, is the better way of freeing a stuck starter. Much easier to turn the engine and hence turn the starter out of engagement with the flywheel in 4th.

If the interior light brightened when connecting the jump leads that indicates there is a higher coltage coming from the donor than the vehicles own battery. This could be because the own battery is bad, or the connecttions to its posts are bad (the jump leads usually being clipped onto the conenctors not the posts) or the donor engine was running.
Paul Hunt

I just returned from an expedition to the underside of my MGB, and here's what I have to report:

1. When starting, the lights dim slightly. The battery is clearly low, but not out. When getting a jump (the donor car was running), the lights were all very bright, even with the key in the "start" position.

2. Rolling the car in 4th did nothing.

3. I delivered a few solid whacks each to the starter, solenoid, flywheel housing, and pinion wheel housing. Nothing.

4. The solenoid was loose on the starter.

5. The solenoid had one large bolt and three posts on the front side of it. The large bolt had four connections on it: the huge black cable from the battery, and three large brown cables. Of the three posts, only the middle was connected, to a small white and brown wire. There was also a white and blue wire that was disconnected from everything, but wrapped around the white+brown. It appeared to fit on the topmost post, but would not reach. The bottommost post was very large, and nothing nearby appeared to reach.

6. The solenoid appeared to be quite new. It had some scratches on it, so I'd guess it was refurbed, but it was certainly newer than the starter or anything else nearby.

I think that's everything. If you have any more questions, let me know. Or, if it would be easier, I can take some pictures of what I saw and post those.

Thanks again for your help.
Chris St. Pierre

Chris,
There is one other thing that you can try. On the passenger side of the engine compartment, on the wheel well inner skin, back from the fuse box, in front of the washer bottle you will find a relay that is black and about the size of a quarter roll of quarters. You will see several wires running to it. Notably a white wire with red tracer. This is the ignition relay to the solenoid. The original Lucas unit usually has just about had it by now. The 77-80 MGB's had this relay. There is one forward of the fusebox too. It is for the fans. You can go to any auto parts supplier and get a 5 prong relay to replace it. The new relay usually has a little schematic with it to wire it up. If you have a problem with the new relay wiring it up, let me know. I will tell you which wire goes where.

Safety fast!
mwhitt

By the way Chris, a little tip for charging your battery. Clip the power side of your charger to the bottom fuse in your fusebox and a clean bare metal screw or some such in the engine compartment for the ground. This way you don't have to fiddle behiind the seat. DO NOT try to jump start it this way though. This fuse is always hot and you are just reverse flowing the power back to the battery.
mwhitt

Loose solenoid???

Tighten that pup down so it doesn't jam and try again.

Best place for jumping the "B" is at the solenoid. pull back the rubber boot (if it's still there) and clamp the "+" lead there and clamp the "-" lead to a nearby radiator support bolt.

Those relays for the ignition usually exhibit symptoms of crank, crank, crank with no spark.

Mike!
mike!

The white wire with the red tracer is the one that energizes the solenoid. It has nothing to do with delivering spark to the distributor.

Safety fast!
mwhitt

White/red energises the starter relay, it is the white/brown that energises the solenoid. The white/light-green is the coil boost connection that is used during cranking but if you aren't cranking yet it can be ignored! If the lights are still bright when you have turned the key to the 'start' position then you aren't energising the motor. What you are hearing is either the 'click' of the relay high up on the RH inner wing, or the 'clunk' of the solenoid low down on the engine.

If you are hearing the relay but not the solenoid then either there is no 12v on the brown at the relay, the relay isn't extending the 12v down to the solenoid, or the solenoid isn't responding to it. Use a voltmeter to determine which.

If it is the solenoid 'clunk' you are hearing then either the solenoid contacts aren't extending the 12v to the motor, or the motor is not responding to it. In the first case there is sometimes a copper link between the two that you can get a voltmeter on, sometimes it is too well insulated and you cannot. In the second case a dead segment on the commutator can be the cause, and rotating the end of the motor shaft with a small spanner (if possible) can bring different segments into play and the motor will then work normally. But sooner or later it will end up on the dead segment again. In either case you will have to get the starter out and either replace it or rebuild the solenoid or motor.

Dead ignition relays are something else altogether, the engine will crank but not start.
Paul Hunt

Thank you for the technical Paul. You are correct, but I would still check that relay Chris. It is cheap and easy to get at. Paul, when the starter bendix locks out on the pre 68 cars here in the USA, I have found that rocking the car back in forth in gear does work. But later I learned on those starters that there is a square on the back of the starter shaft that can be rotated with a 7/16" wrench. This screws back in the bendix. I have found that lubricating that bendix with lithium grease stops that problem. However, later cars that do not have that starter without the solenoid mounted on top do not "lock up". At least I have never seen it in over thirty years of owning and maintaining British cars. The solenoids on the later cars do go out. Have someone engage the ignition switch while you listen in the engine compartment on the drivers side of the engine compartment. If you hear a click at the relay and nothing at the solenoid then the solenoid is suspect. If you here a click down at the solenoid and at the relay then the solenoid is suspect. I find it odd that so many say stay away from that relay when I have found it to be the problem on numerous occassions in my business. It is called troubleshooting from the easiest and cheapest first.

Safety fast!
mwhitt

Paul--

I can hear the solenoid clunk. I'll try rotating the motor tomorrow. Thanks.

Victoria British sells rebuilt starters for $130, but they'll give $30 for a good core. How do I tell a good core from a bad core? Or will it be blatently obvious? Or is it already obvious, from the problems I've got, that the core is bad?
Chris St. Pierre

My 1977 B had similar problems, twice. The first time I replaced the relay mounted on the passenger side wheel well under the hood...it's the thing that looks like a film cannister.
The second time, the battery terminal was corroded and needed to be replaced.
Both fixes were cheap and easy once you figured out where the problem was.
Randy
randy olson

mwhitt - I'd agree with you in that I have never known a pre-engaged starter lock up either, but there have been two or three claims just in the last few weeks that this indeed has happened.

Chris - I think by 'good' core they mean rebuildable i.e. not physically mangled or fire damaged.
Paul Hunt

About 8 years ago for my business I ran a petrol engined Talbot Express (Peugeot 2 litre engine) with pre-engaged starter. This would regularly lock up. Battery excellent, all leads had good connections. Never did find out exactly why it played up but suspected a bad segment on the commutator as a quarter turn with a spanner on the square ended shaft and she would start straight away!

Laurie Webb
L Webb

Well, there you go Paul. It just goes to show you that if you stay around these animals long enough anything can pop up. Didn't mean to sound like I was slighting a fellow bender of the wrench.
mwhitt

mwhitt - sorry if I made you think I had, no slight received.

Laurie - not cranking because the pinion has jammed with the flywheel and not cranking because it is on a dead segment are two different things. The former is characterised by lights dimming as you turn the key to 'start', the latter by no dimming. Rocking the car in 4th often clears the first but never the latter. Turning the end of the shaft with a spanner should clear both, and is usually much harder to turn with the former than the latter. When my Mini inertia starter used to jam I always rocked it out as it was easier than fiddling about in the boot to find the right greasy spanner.
Paul Hunt

Paul

Sorry, didn't explain it very well! Talbot Express starter wasn't "jamming" with the flywheel as it always turned easily. Starter was removed at one stage and both pinion and ring gear were fine. The squared shaft could be turned by hand but I generally used a spanner from above instead of having to lie on the ground to reach up to the starter!

Laurie Webb
L Webb

Whew! I got my new starter today, and I've got it bolted into place. Unfortunately, I don't know how to hook it up, and I don't want to screw it up. My old starter had three posts and a big bolt. The big bolt had three big brown wires and the battery cable attached to it, and the middle post had a small white and brown wire on it. There was a small white and blue wire nearby connected to nothing. Now that I've had a chance to get under the car with really good lighting, I found a nearby largish green wire that was connected to nothing.

Here is a picture of my old starter, with the posts numbered and the bolt indicated: http://www.nebrwesleyan.edu/people/stpierre/old.jpg Post number two was connected. Post three has some wear on it, evident in the picture, but nothing connected.

My new starter has four posts on it, plus the big bolt. I've reconnected the bolt as before, but I'm lost as to the posts. Here's a picture of my new starter, again with posts numbered and bolt indicated: http://www.nebrwesleyan.edu/people/stpierre/new.jpg

If I had to guess, I'd reconnect the brown and white to post three. But the green wire could connect to either posts two or four, and the blue and white can't connect to anything; it won't even reach. Posts one and two are in contact with each other and with the battery connection bolt.

Does anyone have any ideas of how to hook this thing up? Thanks.

Also, while I've got the front end of my B up on stands, is there any routine maintenance I should take the opportunity to do?
Chris St. Pierre

Put the battery cable and the three brown wires on the big bolt as before. Take the spades off if they are in the way, these are used on earlier cars for the brown wires. The white/brown (solenoid) should go on the larger of the two other spades, the light-green/white (coil boost) on the smaller, if the sizes are different. I think the originals were but rebuilt units seem to have them the same size. If the light-green white doesn't reach then was it connected before? If so it should reach now, if not then you may get difficult starting in cold or damp weather.

If it doubt connect a ground to the body of the starter and tap 12v to each of the spades. When on the solenoid spade it will make a loud click (moving the pinion gear) and this takes the white/brown. On the other spade (the coil boost) it will do nothing and this takes the light-green/white. With 12v connected to the big bolt *and* the solenoid spade the solenoid should operate and the motor should spin, and there should be 12v on the coil boost spade. Do these tests before fitting to make sure the starter works. You don't need jump leads to do this, just 'ordinary' wires, as the motor doesn't take that much current when it is not turning the engine and it is safer.

The green (fused ignition) wire is something else altogether, probably fallen off the induction heater at the carb if it comes out of the loom, or a PO wire if it doesn't.
Paul Hunt

Okay, I've got the new starter connected. Still doesn't start. When I turn the key (with a running car connected for the jump), I hear multiple rapid clicks of the solenoid, and sometimes a slight, very low whirring, like the starter engine is trying to turn, but can't. I rocked the car (in reverse, as I park with the nose of the car pointed uphill), and that didn't solve the problem. I tried getting it rolling and popping the clutch, but that didn't start it either, although I probably wasn't going fast enough.

I really don't want to break down and get her towed to the shop, especially having already spent a hundred-some on a new starter. Does anyone have any ideas? Thanks for all your (continuing) help.
Chris St. Pierre

Sorry to hear that Chris. Until the experts reply, here's my best guess: there is not enough power getting to through the main circuit of the starter, although there is enough allow the solenoid to work. So, you are not getting full current from the battery (check battery terminals and the main feed), or the earth strap from engine to bodywork is rotten, or as RLC pointed out, a dead cell in the battery could be the issue. The quick check for the earth would be to run a jump lead from any good point on the engine block across to anywhere on the body where you can get a good contact. For the battery cell, I suppose if you take the cables off it completely and attach the jump leads to these (whilst it's out of the picture), that would tell you. If it still won't turn over after these two checks, I'd reconnect the battery and attach the positive jump lead directly to the starter terminal (much care!) and the negative to the body. That would tell you if the live path from battery to starter is the fault. HTH, and if your old starter is good there's always ebay!
Steve
Steve Postins

What Steve says makes a lot of sense too. Several years ago, I experienced a slow to no crank problem. After trouble shooting, I found that the battery ground cable had corroded in two inside the insulation. It looked fine outside, but after slitting the insulation once I figured it out, the copper wires had corroded cleanly in two.
mwhitt

Chris. You are expert enough. Your suggestion would be the first one I would follow.

I have had this problem several times over the last few years. Only once was it the starter and it gave warning before going out. It was a pre-engaged type on my 68 and jambed twice, having to be rocked to free it, before finally going out.

Both of the other times I had this problem it was the cable from the positive terminal of the battery to the starter which proved to be the problem. I suspect that this is going to be a problem for a number of people in the future as the internal corrosion builds up and the wires are eaten away.

The method I used to check out this problem (after having replaced a starter the first time and having it fail to function, just as Chris mentions) is to hook a jumper lead to the starter terminal long enough to go up into the passanger compartment. I used a large spring clamp, similar to what is used on a battery charger, on the end connected to the starter. The other end had a smaller connector to hook onto the positive probe of my volt meter. The negative probe can be grounded to the door frame. You should have battery voltage, or about 12.5 volts, when you check. Then, try to crank the starter and see what your voltage is. The last car I did this on, the voltage dropped to about three volts indicating a bad cable or connector. (If you have the aftermarket terminal clamps, the ones that connect to the heavy cable with a strap having two bolts, they frequently can go bad.)

Another possiblility is a bad battery. I just had one go out causing this problem. The battery voltage was 12.5V. When I turned the key to the run position, the ignition warning light would come on. When I turned to the start position, nothing would happen and the ignition warning light would go out and not come back on. Replaced the battery with a good one and, so far, it is working properly and showing a good charging rate.

Please let us know what you find and, perhaps, we can focus in on what is actually happening. Les
Les Bengtson

This thread was discussed between 19/01/2005 and 31/01/2005

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.