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Hot!Mower spins but won’t turn over

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soulsnipes40
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2019/09/21 10:24:43 (permalink)
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Mower spins but won’t turn over

I have a Craftsman YT3000 that suddenly stopped working. I noticed the intake pushrod was bent but the valve seat didn’t move. I replaced the head gasket that looked blown and replaced pushrods. When I attempt to start it, it spins but won’t turn over. Also, it was backfiring a few times as well. Is it something with fuel or possible camshaft?

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    AVB
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    Re: Mower spins but won’t turn over 2019/09/21 11:38:44 (permalink)
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    The engine should not turn over if it is bolted down. <LOL> But I know what you mean as it will not start and run.
     
    Then the question is did the valve guide move? Another question about the backfiring as I know most says backing even when it is out the exhaust. Is out the exhaust or intake? Also I had one 310000 series that was what I call sneezing out the intake which was an intake air leak but was when the engine was running.
     
    Depending on the engine model, type, and date code as I assume it is a single cylinder Briggs. It can be a sheared flywheel key on top of the valve problem. Especially if  it is older 280000, 310000, or 330000 series.
     
    As to if it a camshaft problem depends if the valve lift is correct or not. I have yet to see a cam lobe to rotate on the camshaft.
    post edited by AVB - 2019/09/22 09:08:57
    kshansen
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    Re: Mower spins but won’t turn over 2019/09/22 08:58:04 (permalink)
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    As some terms are being being used in a confusing way can you confirm if when rotating the crankshaft the rocker arms are opening and closing the valves? Also did you adjust the valve clearances with crank shaft in the correct position?
    AVB
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    Re: Mower spins but won’t turn over 2019/09/22 09:14:27 (permalink)
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    Was it what I posted that need clarification of?
    kshansen
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    Re: Mower spins but won’t turn over 2019/09/22 09:26:35 (permalink)
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    AVB
    Was it what I posted that need clarification of?


    No, I was referring to the original posters use of terms. I see this on many different forums. One I have seen often is someone saying their engine "will turn over but not crank!" The "crank" turns out to mean it will not start and run. Can be very confusing at times. Samething about the term "Back Firing" to me that term would say it is firing out the intake or carb and not going out the muffler.
     
    If you want to have some real fun try troubleshooting something with someone from England or Australia! Hard to believe we share a common language at times!
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/22 10:10:11 (permalink)
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    Trust me I understand the lingo can be confusing. What I meant is the flywheel is spinning but engine won’t crank over/start. The valve guide looked to be seated correctly and didn’t move. I took off the air filter and sprayed a little stater fluid and then it would “backfire” out air intake. I made sure the valves were set at the right specs and the valves are opening and closing.
    AVB
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    Re: Mower spins but won’t turn over 2019/09/22 11:03:03 (permalink)
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    Okay. Have you check for a sheared flywheel key and it sounds like an ignition timing problem?
     
    The engine model and Type/Spec numbers plus date code/serial number would be helpful in determining a know service bulletin needs applying. As I said if a Briggs the 28, 31, and 330000 series did have some improvement made due to flywheel/crankshaft problems shearing keys on early models.
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/22 11:33:42 (permalink)
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    I checked initially at the flywheel key and it looked ok but I’m going to take another look to make sure I didn’t overlook something. Model 917.289210 engine # 331877. Appreciate it!
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/22 14:53:57 (permalink)
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    So I checked the flywheel key and it was sheared in half. I put in a new flywheel key but same thing is happening, it’s not starting. Also my brand new battery is draining under 12 volts when attempting to start it a few times
    AVB
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    Re: Mower spins but won’t turn over 2019/09/22 16:54:11 (permalink)
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    This is why I asked for the engine's date code so you would be using the correct key and torque specs. First if it has a date code before 120701xxxxxxx the key needs to changed to a steel key and the flywheel torqued to 110 ft-lbs. After 120630xxxxxxx the key will be the longer 1" key and the flywheel torqued at 110 ft-lbs. Plus during at time in 2016 some flywheels were under torqued from the factory [160501ZDxxxxx THROUGH 160922ZDxxxxx].

    Note also that the flywheel and crankshaft key ways were change at the same the new longer key was issued.
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/22 18:13:29 (permalink)
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    Ok gotcha, the date code was 080709. Do you believe this is the only reason that the mower won’t start due to timing being off?
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/22 18:48:24 (permalink)
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    I checked the part number for the flywheel key and I am using the correct steel key #222698s
    AVB
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    Re: Mower spins but won’t turn over 2019/09/22 19:17:19 (permalink)
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    Actually PN 222698S is an aluminum key and the correct updated steel key is PN 796335. Being aluminum or steel does change the timing just keeps it from shearing easily due to flywheel / crankshaft key way design.
     
    Once the sheared key was replaced it should have at least started on raw fuel introduction into the cylinder or intake provided nothing else out of order.
    post edited by AVB - 2019/09/22 19:18:47
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/22 19:28:15 (permalink)
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    Definitely appreciate the information, I’ll grab the steel version. I’m sort of at a loss to figure why it won’t turn over then. Pretty much checked everything else, besides possibly being a carburetor problem? I’ll continue to see if I can find out the culprit.
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/24 13:11:17 (permalink)
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    So everything is still the same. Flywheel is spinning but not cranking over. Also I have to jump the battery because if not battery goes under 12 volts after a few spins. Also I noticed a lot of oil coming out of the exhaust valve where it connects to muffler
    Roy
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    Re: Mower spins but won’t turn over 2019/09/24 13:24:52 (permalink)
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    If the flywheel is spining it is cranking over, just not starting. Recheck the push rod, it may be bent again indicatinng a loose valve guide. Did you properly torque the flywheel nut? If not it may be sheared again.
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/24 13:30:11 (permalink)
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    Yeah not starting, I’ll check the pushrod again and I torqued it to 110
    AVB
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    Re: Mower spins but won’t turn over 2019/09/24 14:31:02 (permalink)
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    soulsnipes40
    So everything is still the same. Flywheel is spinning but not cranking over. Also I have to jump the battery because if not battery goes under 12 volts after a few spins. Also I noticed a lot of oil coming out of the exhaust valve where it connects to muffler

    Something definitely not right as there shouldn't be a lot oil coming out the exhaust at any time. Is the crankcase overfilled? If so then it is likely the carburetor is leaking and has flooded the cylinder and polluted the oil with fuel.
     
    A flooded engine will not start.
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/25 10:10:12 (permalink)
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    Is it best to install a manual shut off valve to stop gas flow in the case the carb solenoid or carb doesn’t stop gas flow?
    soulsnipes40
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    Re: Mower spins but won’t turn over 2019/09/25 11:41:54 (permalink)
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    AVB thanks so much for all your help. I emptied the crank case and installed a shut off valve. I cranked it over and after a few seconds it finally started. There was white smoke coming from the exhaust and the muffler was getting very very hot. Reasons for this?
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