Skytec Starter Grinding

[trecool44]

Hello.  I finally finished putting my newly overhauled O-360 in the M20C.  When attempting the first start in the plane it rotated one blade then made grinding noises.  I can see some new wear marks on the starter ring that only come half way across the teeth.  Voltage and ground are good at the starter.  Tried new solenoid and same issue.  Anyone have an idea why the starter is not fully engaging?  Thank you for any input.

[ShuRugal]

Hello.  I finally finished putting my newly overhauled O-360 in the M20C.  When attempting the first start in the plane it rotated one blade then made grinding noises.  I can see some new wear marks on the starter ring that only come half way across the teeth.  Voltage and ground are good at the starter.  Tried new solenoid and same issue.  Anyone have an idea why the starter is not fully engaging?  Thank you for any input.

Gear mesh too tight?

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[Guest]

11 hours ago, trecool44 said:

Hello.  I finally finished putting my newly overhauled O-360 in the M20C.  When attempting the first start in the plane it rotated one blade then made grinding noises.  I can see some new wear marks on the starter ring that only come half way across the teeth.  Voltage and ground are good at the starter.  Tried new solenoid and same issue.  Anyone have an idea why the starter is not fully engaging?  Thank you for any input.

Possibly the wrong starter or wrong ring gear on the engine, they are available in 122 and 149 tooth versions.

Clarence

[trecool44]

I used the same starter and ring gear from the old engine.

[trecool44]

after another look I realized the gears were only meshing on the beveled tips of the teeth.  How much usually meshes?

[N201MKTurbo]

Which starter do you have?

Which solenoid did you change the one on the starter or the one on the plane?

[trecool44]

It is a skytec LS.  I changed the solenoid on the starter but I'm pretty sure that wasn't the problem.  I am very confused on how the distance between the ring and the gear could change since it worked on the old engine.  What do you think?

[ShuRugal]

1 hour ago, trecool44 said:

after another look I realized the gears were only meshing on the beveled tips of the teeth.  How much usually meshes?

the whole gear should mesh, that's why it's there.  Assuming your solenoid is not bad (sounds like it could be) I would adjust the alignment of the starter to loosen it up a bit so the pinion can deploy and engage fully.

[N201MKTurbo]

When the bendix gear is fully extended it should ride on the inner surface of the housing. Is it going out that far? Is the ring gear centered in the opening? Is the propeller clocked wrong? Does it stop in the same place it used to?

[trecool44]

The bendix is extending fully.  The propellor is clocked correctly (timing marks on starter ring verified and prop was marked before removal).  What could cause the starter to be too far away from the crank centerline?

[RLCarter]

46 minutes ago, trecool44 said:

The bendix is extending fully.  The propellor is clocked correctly (timing marks on starter ring verified and prop was marked before removal).  What could cause the starter to be too far away from the crank centerline?

What you are saying is either the starter assembly is too far aft or the ring gear is too far forward, is this correct?

Edited March 18, 2018 by RLCarter

[ShuRugal]

The bendix is extending fully.  The propellor is clocked correctly (timing marks on starter ring verified and prop was marked before removal).  What could cause the starter to be too far away from the crank centerline?

Reading this, I just realized that I misread your previous post.

The gear mesh should have a few thou gap. When doing non-aviation gear mesh, I usually use a piece of paper folded in two as a gap tool: feeding the paper through should crease the gear tooth pattern into the paper, but should not tear it or add notable resistance when turning by hand.

For the proper spacing on an activation starter, is say read the engine service manual to find it.

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[N201MKTurbo]

I suppose if they reworked your crankcase by milling the parting surface and then align boring the crank bearing journals it could have moved the mounting pad a bit closer to the center line. You may have to shim the starter to get the correct clearance. I'm not aware of shims for aircraft starters, but you could make some from shim stock. 

[N201MKTurbo]

Although if the bendix is fully extending then that wouldn't be the problem.

[N201MKTurbo]

So, it doesn't look like this?

[trecool44]

It does resemble that to an extent.  Mine does mesh about .040 and doesn't look so ripped down towards the tip. And for clarification the bendix is extending fully.  The engine will crank until the first compression stroke then the starter pops over the ring gear teeth.

Edited March 18, 2018 by trecool44

[ShuRugal]

It does resemble that to an extent.  Mine does mesh about .040 and doesn't look so ripped down towards the tip. And for clarification the bendix is extending fully.  The engine will crank until the first compression stroke then the starter pops over the ring gear teeth.

The problem here sounds like too much slop/not enough mesh. Is the starter the correct one for that engine? Is the flywheel?

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[trecool44]

It is the same starter ring and starter from my old O-360.  I'm having a hard time contemplating how that distance could get bigger. 

[ShuRugal]

It is the same starter ring and starter from my old O-360.  I'm having a hard time contemplating how that distance could get bigger. 

Is there a shim under the starter? Is the new engine the exact same sub-model as the old one? I think all the C models use the A1D, but I could be wrong, there.

 

 

[carusoam]

The Bendix is known for getting rusty and not extending fully.... annual lube usually takes care of this on outdoor birds...

In this case, it sounds like the relationship of the starter and the ring gear has changed distances... the ring gear gets heated and put in place.  It holds tight, once it is cooled...

There is probably an installation procedure that covers this.  Or a mechanic that knows how to shim/adjust the relationship.

Rich’s photo above shows the general relation ship of where the outer case of the starter sits compared to the ring gear.

Shu somewhat described how gears need to be placed properly for proper meshing.  The face of one tooth lines up on the face of the opposing gear’s tooth.  The middle of the teeth slide past each other as the drive gear drives the driven gear... middle from top to bottom, and middle from left to right...

It is quite possible that something has moved, Got machined or something like that needs to be accounted for with a shim of the right size and dimension...

PP thoughts only, not a Mechanic...

Best regards,

-a-

[trecool44]

There is no shim under the starter.   The only thing that comes to mind is that the starter is bent from a kickback in history and the was just on the verge of working with the old engine.  This engine might just be different enough to make them too far apart.  Just an I idea though.

[RLCarter]

Pictures?

 

[ShuRugal]

There is no shim under the starter.   The only thing that comes to mind is that the starter is bent from a kickback in history and the was just on the verge of working with the old engine.  This engine might just be different enough to make them too far apart.  Just an I idea though.

If the starter was bent, the Bendix drive would likely be siezed.

Easy to fix it thats the problem, though: shim it unevenly to bring the pinion closer to the flywheel.

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