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dmm3295

B & S 445777 Lost power

DMM3295
11 years ago

I have a B&S 445777 that upon starting, gave out a backfire & then started knocking. That dissipated & I then engaged the PTO. The engine then got louder, a faint knock. After about 10 minutes, the engine started to labor. It lost power & speed rapidly. I killed the PTO & it made no difference. I turned it off & waited 10 minutes. I restarted it, it backfired twice & ran very slow.

The oil level is ok & clean. Any ideas??

Comments (9)

  • bill_kapaun
    11 years ago

    Pull the valve covers and examine the push rods.
    I've got a hunch you'll find something "awry". IF not, I suspect worse.

  • DMM3295
    Original Author
    11 years ago

    Thanks Bill. Maybe a bent push rod??

    This tractor seems to "eat" engines. This is the second one in 4 years. The first threw a crank shaft through the crankcase. I rebuilt this one 2 years ago after it was using oil @ a high rate. Ran fine up until yesterday....

  • bill_kapaun
    11 years ago

    Yes, "maybe" a bent push rod. Possibly worse. Hopefully better.

  • DMM3295
    Original Author
    11 years ago

    Bill,

    Found both push rods bent on cylinder #1. Everything else checks out ok.

    Thanks again.

  • walt2002
    11 years ago

    You need to find out why they bent. Most often a cooling problem, plugged cooling shroud, cooling fins resulting in the valve guides moving up until they hit the valve spring retainer and bending the push rods. Some say ethanol fuel is causing valves to stick and move the valve guides. I have no opinion on this.

    I have a fix for loose valve guides plus detailed instructions on adjusting the valves IF you would like them. Address below, put in proper format and remind me, model number etc.

    Walt Conner
    wconner5 at frontier dot com

  • DMM3295
    Original Author
    11 years ago

    Thanks Walt,

    I believe they bent when I tried to start the engine. I turned the key for a split second & released. It kicked back & backfired. I didn't have a problem before that. Does that sound like it might be the cause?

  • mownie
    11 years ago

    You need to follow Walt's advice and thoroughly check under the sheet metal cooling ducts/shrouding for some type of blockage to air flow from the flywheel fan.
    The scenario you described sounds like cylinder #1 may have overheated.
    Another possibility could be that the INTAKE valve was stuck to the valve guide in the open position and when you started the engine the piston struck the open intake valve.
    That impact likely bent the intake push rod and might also have broken/bent the intake valve.
    After that, there may have been some loose pieces of valve that got against the exhaust valve and when the piston hit that......the exhaust valve push rod got bent.
    Do either of the valves appear to be "sticking out" too much or too little?
    Do either of the valve springs appear to be compressed?

  • walt2002
    11 years ago

    "I believe they bent when I tried to start the engine. I turned the key for a split second & released. It kicked back & backfired. I didn't have a problem before that. Does that sound like it might be the cause?"

    No.

    Walt Conner

  • DMM3295
    Original Author
    11 years ago

    The exhaust valve was frozen. Upon further review the cooling fins were clogged with dirt, oil & grass so your theories about over heating were correct. Bought new valves, guides & tappets. Thoroughly soaked & cleaned all the fins on both sides.

    Thanks again guys.

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