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 MGA - Starter won't turn over

Hi Gang,

The rebuild is complete! engine in, carbs adjusted and installed, and the engine is ready to be fired up.

One problem though - the starter won't turn over. I got a fresh battery and nothing. Cable connections are solidly attached, all of the other electronics on the car work fine. The headlights do not dim when I try to turn it over. The cable to the solenoid seems to be working ok from a mechanical standpoint.

What next?
R Stokes

Hi Rob. Check the battery for a full charge with a hydrometer. Clean ALL connections at the battery. Make sure the ground strap that goes from the motor mount to the motor is in place and is clean and tight. Re check all ground connections. Check connections to the starter switch. All metal connection points need to be CLEAN, bare metal. If all else fails, try connecting a known good battery directly to the starter motor. If it then spins, you have either a starter switch problem, cabling problem, or ground problem. If not the starter would appear to be defective and should be removed and tested. Cheers! Glenn
Glenn

Hi, Rob - lots of good advice in what Glenn says. It certainly looks like you have an 'open' circuit, which causes at least as many problems as it's nasty brother, the 'short' circuit, but gets practically no publicity since it's not so obvious, what with sparks, smoke, fire, and such.

The easiest test is to take one side of a set of jumper cables and go between the 'hot' side of the battery and the big terminal on the starter motor. Obviously make sure you're in neutral, cause if the starter is good, it's going to try and spin the engine. It's best to clip onto the starter post, then touch the jumper cable directly to the 'hot' battery post. This bypasses all the high current cabling, the starter solenoid (or switch), and the cable ends and terminals in one fell swoop.

If nothing happens, and you did remember to install the engine ground cable when you rebuilt the car, then it's out with the starter. But, big spark, and the engine spins, then you've got to localize the problem further. Same jumper cable trick, or a bolt or screwdriver between the big posts on the solenoid will eliminate it quickly.

Since you've got good headlights, the cable between the battery and solenoid is probably good, but you can use the jumper cable to bypass the solenoid-to-starter cable, too.

Barney Gaylord offers some additional insight on his website located at:

http://mgaguru.com/mgtech/electric/ss_102.htm

Best of luck, and please let us know what you find - - Alec
Alec Darnall

I think I sorted out the problem. I jumped the starter per Glenn's suggestion and the car turned over. I then used a VOM to measure resistance across the ignition switch and it indicated an open circuit, even when the ignition switch was pulled.

Looks like I have a bad switch, is that common? And can I fix it myself?
R Stokes

Hi Rob. If you are referring to the starter switch, which connects to the starter pull on the dash, NO you cannot repair this switch, as it is a sealed unit. You need to purchase a replacement. These switches are usually pretty durable, but the contacts eventually burn, rendering the switch useless. To check the switch use jumper cables to short out the 2 terminals on the starter switch. If the starter spins when the switch is bypassed, then the swith is defective for sure. Cheers! GLenn
Glenn

The original MGA starter switch is indeed a durable part. Mine is still going strong at 48 years and 347,000 miles.

I do have a well documented case of failure of an aftermarker part, including conclusions on multiple problems contributing the failure. See here: http://mgaguru.com/mgtech/faulty/ft004.htm

If you have a failure of an original type starter switch with the black bakelite insulator, I would be delighted to take this example off your hands for an autopsy.
Barney Gaylord

"It's best to clip onto the starter post, then touch the jumper cable directly to the 'hot' battery post."

You should always clip to the battery first. The hydrogen generated by the battery is very explosive, and you don't want any sparks near the battery. If you have ever seen a battery explode, you would always remember this.

Jeff Schultz

Barney - no problem, if it's definitely faulty, it's yours.

Anyway I can get this thing fixed today, even temporarily while I order a replacement from Moss? I'm dying to get the car running.
Rich

Hi, Rich - the reason I used the term "solenoid" in my reply was that several MGA's have been converted over the years to using 'modern' electrical starter solenoids, either using a separate push button to activate, or converting to a later three-position Lucas ignition switch with the spring-loaded starter position. You could do this with minimal equipment on your car, either as a temporary, or permanent basis.

You could, however, just raise the bonnet and stick an old screwdriver between the switch terminals every time you wanted to crank, although this would get tiresome really quick. And, the terminals get eaten up fast by the arcing from this method, even to the point where the nuts get welded to the posts and can't be removed.

Although Jeff is correct that there is some danger of battery explosion (yes, I've been "up close and personal" to this experience twice, though the odds are much greater if the battery is actively outgassing), that was my reason behind recommending touching directly to the battery post. This also takes the battery clamp out of the equation.

Either way, best wear safety goggles, or at least safety glasses while you're working around the battery. Cheers - - Alec

Alec Darnall

If you want to start the car, and the starter is out of commission, why not just use the hand crank? I have used it numerous times to start my engine, and it works very well. Just remember to ALWAYS put the car in neutral FIRST, before hand cranking. Also make sure the ignition is on. A tiny bit of ether shot down the carbs will ensure a rapid start. Cheers! Glenn
Glenn

Hmmm, good suggestions, but this is getting trickier and trickier.

First, the hand crank hole is misaligned by about 1/2", so even if I had something to crank it with (I don't), it wouldn't hit the dog nut.

So I tried the screwdriver trick to short out the starter relay and got some unexpected results. First, if the battery is hooked up at all (it doesn't matter if the ignition key is on or off) - I get huge sparks when I short out the terminals. I whipped out a VOM and found that I'm getting 10+ volts across the terminals to the relay, regardless of where the key is. I would assume that I should only get voltage there is the key is on??? I also get 10+ volts if the starter switch is pulled from the inside of the car - I guess this confirms that the switch is bad.

Second, shorting out the terminals didn't turn the starter over. Nothing, nada, zip. Just sparks.

Third, I double-checked, and connecting a portable battery starter between the starter terminal and the frame resulted in the engine turning over. The starter is definitely good.

So what gives? Can you guys explain this to me?

-Rich
R Stokes

Hi, Rich - Ignoring the ancillary circuits, the only purpose of the ignition switch is to supply voltage to the ignition coil, so that when the points open and close, you get spark. So whether it's "ON" or "OFF" has no effect on the starter switch operation. Did you ever run the starter for a few seconds with the ignition switch turned "OFF" to prime the oil pump before you allowed the engine to start?

The starter switch, on the other hand, is connected to the battery on one side, and the starter on the other side, so it is a continuously 'live' circuit. With a high current load on one end (which means low resistance) by measuring across the starter switch you are essentially measuring battery voltage with your VOM. Ten Volts is kinda low, though, so I'm wondering if your battery is getting a little weak from all your testing.

When you pull the switch, you're doing the exact same thing as shorting out the terminal posts with a screwdriver, with two exceptions. One, the sparks take place within the switch housing, where you can't see them. Two, the sparks are less, since they're copper-on-copper, and not copper-on-steel which produces the big sparks you see. Regardless, the trick is not to flinch when you short out the switch, and to accept these sparks as normal. But, the switch's terminal posts WILL suffer.

You're right, if you still read good voltage across the switch terminals when it's pulled, then Barney has a new patient for his autopsy table. I read somewhere that you can place the plunger of the switch in a drill press, grab the switch body and pull down on it while turning on the drill press to clean the internal contacts. Sounds dangerous to me, and if I tried it, I would use low speed, and a pair of really heavy leather gloves for safety's sake, and obviously do a trial run manually, before I switched the drill press on. Some switch plungers may not turn freely, at all.

The only other 'gotcha' I can think of would be a cable that's rubbed and shorted to chassis ground, but the new condition of your rebuild, plus the tests you've already done seem to make that possibility a very long shot.

I think you're very close to getting this sorted. let us know what you find. - - Alec
Alec Darnall

Hi Alec,

That explains a lot, sounds like the voltage is normal then. I never tried to run the starter without the key in, so I assumed it wouldn't do anything.

Note that I said 10+ volts ... it's probably 12.6 or so, it's just that I have my VOM on the 10V scale to make it easy to see the needle moving.

This battery is still fully charged - I haven't run the starter at all on it yet, all of my testing has been run with the portable battery charger.

It sounds like I need to make a better connection across the terminals to see if I can get the current to run past the switch. Not sure how to do that, I thought I had a solid connection with the screwdriver, but I guess not.

More results coming...
R Stokes

Hi Rob. Do this: Get a set of booster cables. Connect one end of the booster cables to each of the the starter switch terminals. Mow take the other end of the cables that are unconnected , and firmly hold the ends together. This bypasses the starter switch entirely, and connects the battery in your car directly to the starter motor. If the motor now spins, then the switch is bad. If the motor doesnt spin, then either you have a dead or weak battery, dirty battery posts, dirty or loose battery cable terminals, bad connections at the stater switch, or dirty or loose connections for the braided ground strap running from the frame side of the motor mount, to the engine motor mount. If this ground strap is loose, dirty ,or missing, the engine, and therefore the starter motor has no connection to ground. Check this ground strap very carefully. I would take this ground strap right off the car, clean the ends, and clean the motor mounts and frame mounts down to clean bare metal where the strap mounts. Then reinstall and fully tighten the ground strap fasteners. While a remote possibility, you could have a defective battery cable. The battery cables, especially the car length one, should be inspected front to back. The cable should be one long piece of cable. Splices of any sort would warrant removing the cable and replacing it with a new one. Cheers! GLenn
Glenn

Hi guys,

I'm on my way out the door so I won't be able to get booster cables today. However, I have made some more progress (a lot more, if you considering starting the car progress):

* Voltage across the switch: 12V or so (analog meter, not too accurate)
* Shorted the switch out with a pair of pliers - lots of sparking, but the starter won't turn over.
* Battery is brand new, totally charged up. I also have access to a 2nd battery, also well charged, and swapping either out doesn't solve the problem.
* Hooking up the portable jumper directly to the battery cables doesn't give the car any juice whatsoever ... probably not indicative of a cable problem, as I would expect to at least see headlights. Probably a weak connection between the battery cable and the portable jumper.
* I cleaned all cable connections from the starter switch to the starter with a wire brush. Bare metal exposed.

Maybe it's a faulty connection at the engine ground cable? I am reading a positive voltage between the engine and the negative lead to the starter switch, but a dirty cable could prevent enough amperage from getting through to the starter.

Finally, in frustration, I left the battery in the car but used the portable jumper to crank the engine. Lo and behold, the car started! I have a new problem with that, but I'll put it on a different thread.
R Stokes

Rich, If you've shorted across the switch and have arcing without starting, the starter cable or starter may be bad. The cable terminals should be cleaned, whether or not they look clean, and the starter ground should be checked, whether or not a cable provides that ground for you. If all that is good, then the only other option is a bad starter. Since you state that your lights don't dim, I suggest that you check your brushes in your starter, and also your commutator. Obviously if you find a burned up starter you can disregard that last.
mike parker

Mike,

The starter is ok - per my last message, it works great when I hook up a portable power source to it, either directly or via the cable. All cable connections have been cleaned. At this point, it has to be either the switch or the ground cable to the engine.

-Rich
R Stokes

Rich,
Sorry, didn't see all your message. I think you now have to check all connections, etc. Have fun and good luck.
Mike
mike parker

Okay, Rich. Where in Illinois? Anywhere near Naperville?
Barney Gaylord

Hi Barney,

I'm actually downtown. I got the MGA running yesterday and took it for a spin. I've been keeping a portable jumper in the trunk so I can start the car while on the road ;-)

-Rich
Rich

This thread was discussed between 26/08/2005 and 30/08/2005

MG MGA index

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