Moss Motors, Ltd

Hi everyone,

 I have a problem starting my car, that is related somehow to the starter mechanism. It will turn over perhaps one or two compression strokes, then the starter gear is kicked out (you can hear the motor whine as it spins up with no load). At first I thought this was an issue with ignition or mixture, but did some work yesterday, and discovered that the car behaves just the same with the ignition disabled. It just won't crank continuously - the starter won't stay engaged. This means it can take 3,4 or 5 tries to get enough engine rotation before it fires. This problem was present before I rebuilt the engine, but if anything, is worse now

The starter is a rebuilt unit fitted when we got the car, and the flywheel is a new alloy lightweight part with a good ring gear, fitted at the same time.

 Any thoughts please?

 Ed

P.S. I should mention it is an inertia type starter, NOT pre engaged 

 

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I want my MGB

Not to worry - a little investigation showed a loose terminal post on the starter. Tightened everything up and she cranks and starts beautifully.

 Ed

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I want my MGB

Well, she was... for a while.

Pulled off the covers for my weekly trip today, and was greeted with the starter trouble again. It turns through one or two compression strokes before disengageing

I'm going to do some more checks. I know battery cable is all new, as are the terminals, but will check tightness. However, I plan to give the circuit a complete health check.

 Once, after I put things back together last week, there was a squealing sound as I turned the key, with no starter turning. A couple of times there was a click from the solenoid, but no starter at all, then it appeared OK. First port of call will be the solenoid, with my trusty voltmeter - it appears to be the original.

 Cheers,

 Ed 

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I want my MGB

Ed,

What year is this car again? Does it have the later, pre-engaged starter (solenoid on the motor)? or is it the inertia type? (solenoid on the body of the car) In either case, good strong current is needed. But, there are some symptomological differences in figgerin' out what's going on.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Hi Motorbill,

It's a '67 car with intertia type starter. As far as I know (garage job sheet) this is a rebuilt unit that was replaced along with the flywheel, when my wife bought the car before giving it to me to fix properly... The garage fitted one of the (expensive) lightweight alloy flywheels. Starting has always been a bit temperamental, even before I started fiddling with the car (engine rebuild etc.)

As I said, I'm going to pick throught the starter circuit looking for signs of undue resistance. I'll post back later with anything interesting.

 Cheers,

 Ed

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I want my MGB

Hmmmph!

Solenoid seems OK (about 0.1 V dropped during cranking). However, I reached back to check for play in the starter mechanism. I'm not sure how much slop to expect, but the gear feels rather wobbly on the spiral groove AND the motor spindle has some play, radial and axial... Rebuilt indeed?

Time to bite the bullet and dig that motor out of there for a closer look, I think.

Ed

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I want my MGB

Ed,

Yep, dig 'er out. Check to see, among other things, if the pinion springs back by itself once you run it out the spiral with your fingers (off, please!). before you mess with it, apply current and see if the pinion climbs the spiral. There is supposed to be a light coat of light oil on the spiral to make all this work nicely.

When one of these starters isn't working properly, in the manner of which you speak, it is usually because it doesn't have the wherewithall to keep up with an engine which is trying to start. In other words, the starter retreats because it mechanically "thinks" the engine HAS started. In a normal engine, a lack of current or a tired starter will both cause this, but you've revealed another piece to the proverbial puzzle.

This engine has an alloy flywheel. These are light. They reduce the inertial effects inherent in a spinning engine, even at cranking speed. The flywheel may be allowing the engine to more quickly start to spring ahead (accellerate) than would be the case with the old stock heavy unit. Having done so, but not really having enough repititions in the ignition/explosion department, the starter "trips out" and the engine fails to fire. This doesn't mean you can't use an inertia starter with an alloy flywheel. I think it just means that the starter's condition becomes more critical. I also wonder about the ring gear depth on this non-stock part.

Perhaps you should consider (if replacement is inevitable) one of the geared units. These seem to have the bugs worked out of them now, and we employ them with success rather frequently.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Thanks motorbill,

 I had wondered about the possible effects of the light flywheel myself (Physics background occasionally helpful when fixing cars...)

looking under the bonnet, and applying a jump lead to the solenoid, I can observe the very end of the gear fly into the bellhousing, only to be thrown out after a few turns of the engine. The mechanism received a few drops of oil when I had that flexible line failure a few weeks back, though it was no different before or after.

I might well consider the gear reduction unit - my concern is that taking the time and effort to rebuild this starter might not sort the problem. Unfortunately I'm a bit strapped for cash at the moment, having been laid off last month. Plenty of time to fettle the car now though...

 Cheers,

Ed

 

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I want my MGB

Ed,

Sorry to hear about the layoff. The one advantage of self employment is that that can't happen, though I suppose my customers could do it! Go ahead and rebuild the unit if it's electrically intact. The parts aren't all that expensive, and there isn't much to lose. By the way, from what were you laid off? if that's not too personal. I'm just curious. I have known physicists.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Thanks Bill,

I used to work for a Nanotechnology company, as a designer & builder of optical and electronic instrumentation. Also evaluation of new applications for the company product - which were quite wide ranging. Fun while it lasted, but they were experiencing a bit of trouble with the level of $$$$$$$$$$ needed to keep it going...

I'll pull the starter and re-work it. It's possible that it was poorly rebuilt (if at all) and that new parts will help. As commented elsewhere though, I do wish there was a drain tap on the oil filter...

Cheers,

Ed

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I want my MGB

OK new parts ordered, unfortunately some of which are on back-order for a couple of weeks. Never mind. It'll give me time to replace that fuel sender I have been meaning to tackle for months....

Ed

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I want my MGB

OK, finally my starter pinion arrived. Perfect timing, as I have the engine out for some other work.....

On taking out the malfunctioning starter, I see that the pinion is loose in the barrel - able to move back and forth and wiggle noticably. Presumably this misalignment could cause the pinion not to engage fully with the flywheel, or jiggle and work it's way out as  The pinion in the new part is pressed firmly home, so that gives me some hope for a cure to this ongoing trouble.

Ed

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I want my MGB