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    kittenmueller's Avatar
    kittenmueller Posts: 5, Reputation: 1
    New Member

    Jul 31, 2006, 05:05 PM
    Briggs & stratton 12.5
    My husband has an MTD with a b and s 12.5. It has run weill with some babying for a while, now. One day he was running ti and he heard a loud POP , and that was the end. It has new solenoid, starter, bettery and a few other things . The key is it is GETTING gas into the bowl, but not going anywhere else . Fuel pump? He is NOY savvy at these things and has never rebuilt one, but as we have 6 acres and no way to mow it , guess he needs to learn. Any thoughts on where he could start?
    thebriggsdude's Avatar
    thebriggsdude Posts: 1,096, Reputation: 53
    Ultra Member

    Jul 31, 2006, 08:24 PM
    Heard a pop... does the fuel line just run from the tank to the carb? Try a little gas down the carb and see if it'll start. The heard a pop thing makes me think of a snapped connecting rod.. take the plug out and insert a screwdriver into the hole and turn the engine over to make sure the piston is moving in and out.
    kittenmueller's Avatar
    kittenmueller Posts: 5, Reputation: 1
    New Member

    Aug 1, 2006, 04:19 AM
    Ok, I ill try that and get back to you ! Thanks
    kittenmueller's Avatar
    kittenmueller Posts: 5, Reputation: 1
    New Member

    Aug 3, 2006, 05:19 AM
    B and s 12.5
    I posted before on my husbands 12.5 - will not start , but is getting gas to bowl. He has front to head off, He says the rod pushes down but not back up by it's self. Should it have to be running to come back up ? Also said it is really black and filthy inside. Indication os blown ord? Piston? Worked fine, and then he heard a load pop , and after that will not start.
    thebriggsdude's Avatar
    thebriggsdude Posts: 1,096, Reputation: 53
    Ultra Member

    Aug 3, 2006, 11:38 PM
    The piston should move in and out (indicates the connecting rod is connected to the piston and to the crank) that rod delivers the power basically to rotate the crank, the piston is what gets pushed down on the power stroke... it sounds like the connecting rod snapped... now if the engine is taken apart and its just the rod, and it didn't hit ANYTHING when it broke... then you could just have a new connecting rod installed... if it hit something though, high risk of stress cracks which ain't good. Loud pop is pretty consistent with either a backfire, or conrod snapping. Btw, the piston should move in and out, with no help... just by rotating the flywheel or lower crank pulley stack.
    Did it have regular oil changes? Does the oil smell like gas maybe?
    kittenmueller's Avatar
    kittenmueller Posts: 5, Reputation: 1
    New Member

    Aug 4, 2006, 03:58 AM
    HE takes good care of it - regular oil changes, etc. Anal about it, lol. Any idea on cost of new conrod - ballpark, Thanks for the help. Gives me some plave to start!
    thebriggsdude's Avatar
    thebriggsdude Posts: 1,096, Reputation: 53
    Ultra Member

    Aug 4, 2006, 02:26 PM
    Around $20-$30 maybe... can't remember for that exact engine... but the engine will have to be checked for damage and cracks if damaged. Good he takes care of it... by the way, did the oil smell like gas or no?
    sexyfisherman's Avatar
    sexyfisherman Posts: 1, Reputation: 1
    New Member

    Jun 24, 2010, 07:13 PM
    Had the same thing happen to me ,found out that the overhead cam rocker arm worked loose,causeing it to backfire.I tighten it back up ,worked fine after that
    DrStevey's Avatar
    DrStevey Posts: 1, Reputation: 1
    New Member

    Jan 8, 2011, 02:39 PM

    Pull valve cover off. Make sure that your push rods are on the valves. Problem is B&S OV engines pushrods bend and easly go out of adjustment. One pushrod is aluminum and bends very easly. You can straighten it out and reuse it. Or buy a new one . The pop you heard could have been the bolt thet holds the lifter in the head. If it is your head is no good. Sorry. You can find used ones on eBay at fair prices. I have repaired many engines like yours and have all the information you will need to repair your problem. If I can help you out more let me know.

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