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Well crud

1469 Views 6 Replies 6 Participants Last post by  deereboy55
As I have posted in other post I have been mounting a used 8HP. Briggs on my 2550 after the old 5HP. Tecumseh gave up the ghost. Well I had several bugs to work out with the new engine but yesterday I finally got it running. I cut the whole yard and it ran great. The added power was a big plus over the old Tecumseh. When I was finished I stopped the mower, disengaged the blade, and put my hand on the key to shut it off when suddenly POW! The entire mower shook. I shut it off as I was already in the motion of doing. I looked it over and noticed that the muffler was almost blown apart. I pulled the rope and notice right away that there was no compression. The crankshaft spins freely and there is no air puffing out of the exhaust. I just walked off and left it sitting there. :banghead3
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OMG that sure stinks. was it at wot? when you disengaged the blades did the engine rev high?
That is indeed nasty, especially since you say it performed so well just prior to it's catastrophic detonation! This occurred before you actually switched off?
Yes it blew up right before I switched it off. It gained rpm when I disengaged the blade but it was nowhere near wot at the time I shut it off.
Before declaring total disaster, I'd pull the head to see if the valves may be stuck. You had a big backfire out the exhaust, and it may have slammed the exhaust valve open to where it jammed wide open [more than usual, so it stuck on residual valve guide gum].
Can't hurt. This is the exact thing that caused the installation of solenoid operated valves on the bottom of float bowls.
If the switch was still on,the solenoid would still be feeding fuel that's academic anyway since there wasn't a solenoid, Sounds like the Exhaust valve hung open,and the fuel found a hot spot in the muffler,but only a tear down will tell for sure.
pull the spark plug,,,with a small flash light you can see the edges of the valves trough the plug hole , move the wire to the side so you don't get zapped ,,,roll the engine over to see if the valves are both going up and down
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