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The Home Smithy
The Home Smithy, Small Engine Tech
Category: Small Engine
Satisfied Customers: 9623
Experience:  Small engine tech
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The 10 hp ohv b & s engine on my powerboss portable generator

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The 10 hp ohv b & s engine on my powerboss portable generator can only be turned about halfway around by hand, has it seized?


Probably not. You may have a bent valve though. Pull the plug and use a flashlight to look into the cylinder. You should be able to see if the valve is bent. If the valve is ok then something else is restricting the movement of the motor. Have a good look at the generator part of the unit.

Please post any other concerns here.

Best, THS

Customer: replied 8 years ago.
I was wondering if the generator could be causing the engine not to turn over? I will inspect the valve to see if it is bent, although, the generator was purchased new in 2005 and has run great the times I have used it during hurricanes and other power outages. I've taken pretty good care of it making sure oil was changed when recommend. However, I've kept it under an open shed in the backyard - no rain on it, but dusty. Would the generator need to be removed to check to see if still not turning over?

Well i really cant think of anything in the generator that could cause this. When you move it and it stops you should be able to hear anything in the gen section that would do this. eg;, a bolt or nut that has come loose or something like that.

Removeing the gen section is a serious pain so you wll want to avoid doing that if you can.

Customer: replied 8 years ago.
Any thoughts about compression issues, since the thing will turn partly over by hand. Will not turn at all using the rewind starter - I thought at first the rope was tangled on the pully, but after taking the engine cover off - pain - cause the rewind starter is rivited on to the cover the starter worked okay and cord would pull all the way out.
Ok when you turn it by hand can you feel it hit something solid or is it kinda bouncy?
Customer: replied 8 years ago.
Seems like it is solid, turning counter-clockwise, goes about halfway back around to where the magnet on the flywheel alligns with the coil. I haven't tried to force it yet with anything.
ok and going the other way is it solid also or does it feel bouncy, like compression?
Customer: replied 8 years ago.
I haven't felt anything bouncy yet either way.

Ok this is definatly going to be an internal problem with the engine. When you turn the motor can you either hear air escaping from the exhaust port or air being drawn into the carburator? You will need to pull the air cleaner off to hear the carb. You might have to give it a quick spin to hear this also. Try not to ram it into the hard stop. Just enough to hear air flow in either side.


Customer: replied 8 years ago.
I started working on this yesterday, and I put everything back together on the engine, as I didn't know if I would be able to get right back to it. I'll need to disassemble it again to check this out.
Ok take your time. I'll be here when your ready. Check inside the plug hole while your at it. Ill bet you can see a stuck valve in there. Or if anything a bunch of marks on the top of the piston. If th4e piston top is all marked up go ahead and pull the head off. If the cylinder walls are ok you might be able to get away with just a head job. If they are scored then a long block replacement will be needed.
Customer: replied 8 years ago.
I'll get back to you when I check all this out. It's going to take some time, maybe hours, - cause as the old fella says - I know enought about all this to be dangerous!
lol yup know the feeling well. Take your time Im going to be here all day, and most of the evening.
Customer: replied 8 years ago.
Fly wheel is turning all the way around this morning. Is not stopping halfway around. I'll still have to put it all back together and see if the rewind starter will turn the engine over - guess the grimmlins decided to take the day off. I didn't check that other stuff you mentioned about the valve yet, since it feels like it has good compression, today, maybe just a rewind starter issue - I hope - will get back to you.

Well that is good news.

Something tells me that something is still not kosher in the motor. But I wont complain if the gremlins found someone else to pester.

Let me know how it goes.

Best, THS

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Customer: replied 8 years ago.
Got it all back together. After about 3 or 4 cranks it started right up. Had to burn out a little motor oil I put in the spark plug hole, but after 3 or 4 shut downs and start ups it seems to be working good. I don't know what caused it to partially freeze up, except it had been sitting up since H. Gustave. Thanks for you help. D.

Your welcome. Thank you for the accept.

Best, Smitty