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OH NO!!!!Almost


patrician12

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patrician12
This afternoon while on was mowing acre #2 of 5 my 912 with a 16 hp single clyinder stopped after making a metallic sort of noise.I cranked it over and it freewheeled effortlessly.I reached down and turned the crank easily by hand.I cranked it again with the starter.OH NO!!!I know that sound I threw a rod.I towed it back to the barn and took out the spark plug.No compression.All I thought is how can this be.The motor I bought brand new 8 years ago.I change the oil every 10 hours,I monitor the oil all the time and I just put a brand new carb on.I figure I'll pull the head,pull the piston and look at the crankshaft and see if I should even bother fixing it .I took off the head and but no marks on the top of the piston.Piston seems tight too.I spin the engine and up and down it goes crosshatch pattern still on the cylinder.Nice I thought for 8 years of constant use.Then I notice a piece of metal on top of the piston and that the exhaust valve is open.Holy cow the valve is bent.How can a flathead valve bend?I took the valve out,hammered it straight on an anvil,put it in the drill press to check if it was concentric,99.7% good,lapped it and put the engine back together.Started right up and ran perfect.Un- daunted I went back and cut the other 3 acres.After inspecting the metal I found in the cylinder it was obviously a casting spur from the new carb I put in the week before.But still how did the valve bend?Wouldn't the metal just keep it open???
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If the piece of metal sitting on the piston hit the edge of the valve on an exahust stroke it could easily bend the stem...
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maxtorman1234
Sounds like you were lucky, I've never thrown a rod or had troubles like that. What engine was this?
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If the metal had stuck under the valve it would still have been under the valve. Most likely it was on top of the valve to one side. When it opened, it crammed into the head, bending it too one side. Had this happen myself once.
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Dave explained it much better than I did. Also had this happen to a VW when a 10 mm nut went down the intake without me knowing...
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patrician12
It's a cast iron Briggs that til today the only problem it ever had was a dripping two piece flo-jet carb.
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If that was a newer aluminum engine, you mite of not been able to save it. I love these old cast iron blocks Elon
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