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Post by albionwood on Jul 15, 2008 20:52:04 GMT -5
No, I'm not racing my riding mower; the engine started racing, running at high RPM, for no apparent reason. Adjusting carb did no good and I shut it off. Heard a clanking noise... not good! Took the head off and lookie there:  OK, lot of carbon and varnish - this baby was running poorly for a long time, bad gas etc, before I cleaned out the carb. In fact even after two go-rounds with the carb it was still hunting a little at full speed, although it purred nice at idle. But look closer:  Whoa! Where did that little screw come from? It is stuck into the piston head, though it came out easily. You can see where it has been jammed into other places on the piston - banged around in there a few times apparently. Only thing I can think of is maybe the governor came apart inside the crankshaft, and this screw somehow got sucked through the crankcase vent tube into the carb and thence to the chamber. Any other theories?? I'm gonna need some gaskets and probably a governor... |
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Post by lawnmowertech37 on Jul 15, 2008 21:15:03 GMT -5
do me a favor before you go in the engine i need a model and type # off the engine cause you say it started racing all a sudden just need to look at t he diagram so i need that #s
calvin
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Post by albionwood on Jul 15, 2008 22:42:39 GMT -5
Model 31H777
Type 0202E1
I don't have a Briggs manual for this engine - got a Vanguard manual by mistake.
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Post by lawnmowertech37 on Jul 16, 2008 7:47:12 GMT -5
that screw appears to possibly be the throttle valve screw do me a favor take the carburetor off before going into the engine itself the throttle valve check to make sure all the parts are intact its very possible if that throttle valve screw came off it would of got caught up in the fuel intake to the piston chamber that would definitly cause it to run very high rpm if that throttle valve came loose
let me know what you find thanks
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Post by RBW on Jul 16, 2008 10:41:06 GMT -5
that screw appears to possibly be the throttle valve screw Yep, thats what I was thinking. If so, its a cheap, albet delicate fix. |
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Post by lawnmowertech37 on Jul 16, 2008 14:11:54 GMT -5
tell me you did not take the push rods out of the engine those long rods have a color code on one end of one of them make sure if you did not take them out dont remove them for they do not need to be removed if you did take them out make sure they are reinserted the correct way one goes on the intake side and the other on the exhaust side the red band on one of the rods is there for a reason
i would suggest you to clean the top of the piston with a scraper of some kind then use a compressed air on it to blow off the excess oil particles and change the cylinder head gasket with a new one part # 699168
you can get that locally if need be
thanks
calvin
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Post by albionwood on Jul 16, 2008 19:03:43 GMT -5
Yes, you were both right. In fact both screws came off the throttle plate, which fortunately lodged in the intake tube before getting into the cylinder... the second screw made it all the way through, out into the muffler!
I did take the pushrods out, but carefully noted location and orientation. The red band on the steel rod (exhaust, right?) marks the tappet end. The aluminum rod didn't have any color coding that I saw, but I was careful to put it back the way it came out anyway. I assume I should check the clearance on the lifters before firing up.
Do I need to use Loctite or something similar on the throttle screws and/or the rocker arm nuts?
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Post by lawnmowertech37 on Jul 16, 2008 21:27:27 GMT -5
i would not adjust them lifters normally they are ok as long as you did not touch the rocker arm nut
the loctite may be a good idea to avoid it from coming loose again the rocker arm nut no they will normally stay
yea the aluminum rod is always clear and always the intake
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