Small Engines (Lawn Mowers, etc.): broken pinion gear on starter, bolts and nuts, aluminum ring

Question
QUESTION: Hi,

I have a 1997 B&S 15 hp mower (Model 28Q777 Type 0681-01) that has  a third  broken plastic starter pinion gear with very few starts on it. It the aluminum ring gear on the engine and it appears to be okay. No damaged or missing teeth. I had to replace the entire starter motor to get a new pinion gear last time.
What could be the problem? If it is the ring gear on the engine, is it difficult to replace and is it still available?
The new starter is made in China could it be defective?
The ring gear is from 1997 and I suppose is worn in a way that is not completely obvious. Could I remove it and rotate it to a new position?
Is there something I am doing wrong installing the new starter? I make sure that the teeth are engaged onto the ring gear okay and it is bolted on extremely tight.

Thank-you in advance for your time and attention,
Dale

ANSWER: Dale
It may be out of line or not tighten down correctly. the ring gear you are using is a aluminum part # 696537 the correct pinion gear is # 695708 Plastic. The ring gear is still available as far as how hard to replace depending on your knowledge and what tools you have. Basically the ring gear unbolts from the fly wheel with 8 bolts and nuts make sure that the ring gear lines up the way you removed you may need to make a mark on the flywheel before you remove it with the flywheel.

---------- FOLLOW-UP ----------

QUESTION: Ben,
Thank-you for the response. If the ring gear is not loose, how will I know if it is out of alignment? I have lots of tools and am capable of removing four bolts if that is all the job requires. Is there a torque specification for them? I have a torque wrench...

If it is loose how will I know where to place it back into alignment? Do I just move it so the teeth on the bendix engage to the middle of the ring gear teeth it is engaging presently?

What constitutes loose? Obviously if the nut moves without a wrench but if it is tight to some degree what then?

Would you go ahead and replace the ring gear just due to age even though it looks fine?

Thanks,
Dale

Answer
Dale
if it is not loose then it is fine does it look like it may be warped from the heat of the engine. Sometime when the starter pinion gets damaged it may not be lining up correct and the starter may need some shims.as far as rotating it that wont help like I said you will have to mark the placement on the gear and the engine.If the spirals on the starter drive are worn, the new pinion gear will not turn freely. This may be the cause of your failure.Also sometimes the valves will cause starting problems You adjust the valves by rotating the flywheel so that th piston is at Top Dead Center on the compression stroke get a feeler gauge and set the Intake Valve Clearance
( in. )003 / .005 and the Exhaust Valve Clearance ( in. ).005 / .007

maybe this will help