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MG MGB Technical - 2 different starters?

I recently bought a new starter and fitted it to my 69 B GT. Now when I start the car there is a clattering metal noise, but only when the starter is engaged. The shop I bought the starter from told me there was only one starter that came on B's and only one drive gear. Is this true, or is it possible that I got the wrong MGB starter?
Any other guesses as to what this could be?
Thanks in advance
Bill
Bill Mertz

No, there were at least two different kinds of MG starters. Someone else will be able to tell you more, but the early cars had interia-engaged starters, later cars were pre-engaged starters. That's all I know.
Kim de Bourbon

The MkI cars (pre-1968 model years), with the three-synchro transmissions used one type of starter. The MkII and later cars used another starter (Lucas 2M100).

I don't think that the earlier starter would even fit into a four-synchro transmission.

Check that the two bolts that secure the starter are both tight. I had a bolt vibrate loose once and it made a heck of a racket. You should be able to see the upper bolt by looking down behind the distributor. The lower one is clearly visible from underneath the car.

SAFETY!!! If you go under the car, make sure the car is on jackstands. I would disconnect the battery. If your wrench slips a little, it can short the starter solenoid. There was a thread a few months ago about a guy working on a VW bus who did this. The drive wheels were on the ground and the car was in gear. A screwdrive shorted the starter solenoid and the car lurched forward off the jack stands, killing him.

I believe the bolts are both 9/16. A socket wrench with a six inch extension will fit above the starter to reach the top bolt and let you have the ratchet in front of the starter, where you can turn it.
Paul Noble

Bill - The other thing that could be causing the noise is a bad ring gear on the flywheel (I know, you didn't want to hear that). It is possible that the new starter is defective, though I am not sure how you would prove that to the place you got it from.

Please head Paul's safety cautions. I would strongly suggest that you disconnect the battery befor woriking around the starter. In addition to accidently turning the drive wheels if the car is in gear and you short the starter solenoid, with that heavy gauge cable from the battery to the starter, if you short that to ground with a wrench, it will instantly weld everything together and the wrench will turn incadesant instantly, doing a real number to the hand holding it. Good luck - Dave
David DuBois

I almost did exactly what I cautioned not to do. I just finished putting my engine/trans back in after a clutch change. While it was out, I took all the ancillaries off, cleaned and painted the block, etc. My car has the inverted, spin-on oil filter. I had removed the aluminum adapter during the cleaning. This apparently tore the rubber adaptor-block seal.

I discovered the oil leak when I started the car (still on jack stands) and oil poured out on the floor.

A few days later, I received the replacement gasket and went out to put things back together. I had connected the battery for my first attempt to start it and had not disconnected it after I found the oil leak.

Now, laying on my back, I tried to thread the adaptor back up through the maze of wiring and stuff from underneath. The adaptor touched the block and the coppper bolt on the starter. The sparks looked like the Enterprise under a Klingon attack. It scared me and I instantly dropped the adaptor.

I disconnected that battery and put the adaptor on from above. Fortunately, when I reconnected the battery, everything was find; no damage had been done.

In my case, all four wheels were off the ground and the car was in neutral, so I probably would not have been crushed by a falling car, but it shows how easy it is to inadvertantly neglect safety.

This is especially true when something unexpected happens. In my case, it was the oil leak. I had planned my work and had taken safety into consideration. Then, when the leak occurred, it disrupted my planned work, and I didn't stop to re-plan the work, taking the new situation into account. I could just as easily have made this mistake with only the front end off the ground and the car in gear.
Paul Noble

Kim is correct

the earlier cars used an inertial starter where the sprocket spins forwards along the shaft against spring pressure- known as a bendix arrangement

later cars use a pre engaged type where a solenoid draws the sprocket into engagement with the starter ring before any rotation takes place

each has its own ring gear and they cannot successfully be mixed


chris
chris

Well after re-checking the torque on the starter bolts they all looked to be in snugg. So I decided to pull the starter. After it was out I looked at the drive gear and only the foreword half (closest to the ring gear) of the gear unit had wear marks on it. Then looking at the ring gear I saw that only the foreword part of the teeth (closest to the starter) on the ring gear were worn as well. I'm no expert, but it seems to me that the starter isn't engaging fully, or it engages fully for a second then backs off a tiny bit, causing the clattering noise I've been hearing. Does this sound logical or am I full of prunes on this one?

Bill
Bill Mertz

"Then looking at the ring gear I saw that only the foreword part of the teeth (closest to the starter) on the ring gear were worn as well"

This is deceiving because the teeth are shaped oddly to allow smoother engagement of the starter drive gear into the ring gear. The first time I saw this I thought the ring gear was bad but after I ordered and received a new one I realized that it was not as bad as I thought
gerry masterman

If you can get to both studs of the solenoid try bridging them with a large screwdriver instead of cranking it with the key. WARNING! Make sure the car is safely supported, ideally on a hoist. Make absolutely sure the car is out of gear. Be very careful the screwdriver doesn't touch any other metalwork. If you can still face doing it after all that, and if it still clatters, it is mechanical. If it didn't do it before then the new starter has to be suspect. If linking the solenoid studs results in a normal cranking noise then either the solenoid is bad (i.e. a bad starter again, this is a known failure mode on V8 starters, at least) or there are bad connections resulting in insufficient power getting to the solenoid. The solenoid takes a lot of current and whilst there may be sufficient voltage getting to it initially, as soon as it connects the very heavy load of the motor to the battery, the battery voltage drops, which means there may now be insufficient voltage to hold the solenoid in. The effect is that the solenoid chatters in and out making and breaking the connection to the motor, making a terrible din.
Paul Hunt

Paul,
I just took the starter in to the shop I bought it from. If I get it back and I still have problems I'll try what you're saying. It makes a lot of sense and seems easy enough to check for.
Bill Mertz

Ok, so I got the starter back, they said it had a bad drive and the clutch (inside the starter) was coming apart. So I mounted it again, and the same exact thing. However upon listening this time I took further note that the clattering noise does not occur until the engine begins to catch. So if you unplugged the coil wire for example, the starter would crank as normal. But once the engine starts fully, and you disengage the ignition crank, the noise ends. Very odd indeed. So I was planning to swap the starter from a '69 MGC that I have on lone into my '69 MGB, and see how that works out. The starters look the same, but just to be safe, did the MGC and similar vintage MGB use the same lucas starter?
As usual, any more guesses might keep some hair on my young head.
Bill
Bill Mertz

Sounds like there is still a problem with the pinion gear/solenoid, possibly being thrown out when the engine catches. I thought the pre-engaged type remained meshed until the solenoid released, unlike the inertial type where the pinion gets thrown out of engagement. Substitution is the only option.
Paul Hunt

Bill


It may be that you have a bad earth on the engine. When the motor starts and takes extra current the solenoid drops in and out.


Just a thought

Steve
Steven Williams

So here's a new update. I swapped the MGC starter in, and although the noise seemed quieter, it was still there. The guys at the shop say the starter isn't getting enough voltage (bad connection or wiring). I checked the ground and it looks secure. I don't really know how to check and chase this with a meter.
Any help?
Bill
Bill Mertz

Check the heavy current circuit as follows:

Put the +ve probe of a voltmeter (analogue is usually best) on the battery hot post (not the connector) and the voltmeter -ve probe on the solenoid stud. Crank the engine (coil disconnected) and note the voltage. Now do the same with the meter -ve probe on the battery ground post and the meter +ve probe on the starter casing.

Ideally you are looking to see no more than about 0.25v on each. Anything more than 1v is worth chasing down and cleaning up as it is sapping voltage from the starter.

Reverse the meter probes for +ve ground systems.

Bad connections in the relay and solenoid circuits can also cause solenoid chattering, check the voltages on the white/red at the relay and the white/brown at the solenoid, should be close to battery voltage during cranking, typically about 10v with a decent battery and connections. The difficulty is that if the solenouid *is* chattering the voltages will be leaping all over the place. Bridging the solenoid stud and the operate spade to crank the engine as previously suggested gets round any bad connections in other than the heavy current circuit.
Paul Hunt

I did as you suggested and bridged the terminals with a large screwdriver. Its still clattering away when the engine begins to catch. I feel like if the heavy current circuit were bad it wouldn't crank so well for so long, but I guess I better check that as well. I'm beginning to think the ring gear is bad. But its strange that with my old starter, before the clutch job it didn't do this. Then all of the sudden it appeared. My starter guy says he'll modify the starter so that the drive releases more quickly.
I'm still at a loss, but may just have to live with it, until something really breaks.
Bill
Bill Mertz

This thread was discussed between 26/07/2002 and 02/08/2002

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