Leyland 600 Starter Problems, HELP!!

[kw573]

Hi all,

I have an old Leyland 600 engine in a M1A1 Heavy Wrecker! That is how I bought it.

Anyway, the rally fast approaches and the starter is playing up badly and I was hoping someone here may recognize the problem and give me a few leads on how to fix it.

It all started with dying batteries which got the solenoid sticking and me diving for the nearest battery terminal to release it. I stripped the solenoid and found badly burnt contacts, so I repaired them by brazing and re-finishing the surfaces. But the contacts still stick frequently.

On top of that, now the pinion will not engage. Hmmm, 2 x 630CCA new batteries plus new leads, but no improvement. Bench tested it at the auto-electricians and it seems to work fine. It spins freely and even violently under power and the pinion throws out convincingly. But the pinion still grinds on the flywheel teeth without engaging. I have rotated the flywheel by hand many times to engage new teeth, left the starter motor about 3/16" off its' seat, rotated the motor in its' mount, ground a lead-in on the brass pinion teeth, hot wired the solenoid in case of low voltage through the switches, all to no avail.

But it all looks to be in good condition!

Any informed ideas would be greatly appreciated. Parts for this would be scarce and very expensive, I expect.

Thanks in advance.

Sam - down-under.

Edited May 28, 2013 by kw573
Typo.

[Gordon_M]

Not a clue, but if you are looking for "why didn't I think of that? " stuff you HAVE checked that the starter is turning in the right direction haven't you? - positive earth / negative earth / direction of rotation sort of thing.

[Grasshopper]

The starters on these engines were common to AEC, Gardener and Leyland engines amongst others.

 

The way they work is the starter motor rotates under low power (supplied through the small centre cable, I forget the correct term for it) while the pinion engages with the flywheel (hence being called a pre-engage starter). When this engages with the flywheel, the main contacts should make and the motor gets full current from the batteries. From the sound of your problem the main contacts are engaging before the pinion is engaged. These can usually be adjusted (I've adjusted a few in my time working on vintage buses but that was 10 years ago) which should cure your problem.

[Tony Graves]

hi kw573, i had a similar problem with one of my diamonds, it turned out to be a bad earth, hope of some help, tony g,

[kw573]

WOW! WOW! WOW!

 

THANKYOU! THANKYOU! THANKYOU!

 

I got the starter going! But not without the info from you guys!

 

I had done an incorrect repair on the burnt contacts, guessing it by common electrical practice. But this solenoid is not common, not in Australia anyway! Once I understood how it worked, I could see where I got it wrong, and made the needed alterations. So thanks heaps.

 

 

Now for the technical stuff for those interested.

 

The earth/power supply was one of the first things I checked.

And, Grasshopper, I had never heard of a pre-engage starter. But it did explain some of the mechanism and wiring that I was unfamiliar with.

 

So, how it works:-

There is a separate circuit to engage the pinion and a separate circuit to drive the pinion. But these circuits are both actuated by the same solenoid, which has a two stage function.

This picture shows the solenoid at rest. The Primary Contact (my term) that actuates the engage circiut through the Intermediate terminal (my term) is open, as is the Secondary circuit (my term)

 

More to come.

Sam.

 

 

[kw573]

. . . . continued.

 

When the solenoid gets power, it pulls in the bridge which closes the Primary Contact and also puts power to the Intermediate Terminal. The Secondary Contacts remain open. This is the first 'stage'.

The Intermediate Terminal powers the low-power circuit that Grasshopper described, pulling the pinion in and spinning it to engage the flywheel. The Trip Arm catches on the Trip Lever, preventing the Bridge from tipping a bit and closing the Secondary Contacts.

 

This is where I made my mistake. The Secondary Contacts were very burnt so I built them up by brazing them, making them the same height as the Primary Contact. This made the Trip Mechanism to be of no effect and the pinion would try to pull in under full power!

 

 

More to come.

Sam.

[kw573]

. . . continued.

 

When the armature throws in, it moves about an inch before the Trip lever is bumped by a ring mounted behind the commutator, lifting it slightly and dis-engaging it from the Trip Arm. This allows the Bridge to tip a bit and close the Secondary Contacts and so putting full power to the already engaged pinion. And the engine turns over!:laugh:

 

 

 

 

Isn't that cool? Very different way of doing things to what I am used to.

 

It is now working perfectly. Thanks gents, especially Grasshopper, who hit the nail on the head!

 

Have a nice day.

Sam - down-under.

[Grasshopper]

I have repaired just a few of those in my time....

 

Amazingly I was able to buy a brand new starter motor off-the-shelf in the 1990s to fit my WW2 AEC Matador, shows you how long that type/model of starter was in production.