I have a Huskee push mower with the Kohler xt650 engine on it. It sat for a year with untreated fuel in it (death in the family I didn't do my chores). I went to start it and it was low power. I cleaned the carb and a new plug. I also installed a new ignition because the plug wire was getting crispy against the exhaust. It runs well without the air cleaner in but bogs down when I put it in (also new). Because of the oil marks on the cleaner I took it apart and cleaned the pcv. Same problem. I noticed today that the carb is blowing not oil but fuel out of it as it runs. Literally with the filter off there is a mist of unburnt fuel that blows out of the carb. thinking maybe bad rings and it was raw oil I took the pcv arm off and even more blew out the unrestricted carb hole. I put my hand in front of the hole in the carb and was able to literally get gas dripping off my hand. Knowing how engines work I am guessing the intake valve isn't closing but I have never seen this before. Can anyone point me in the right direction on this? If it is what I'm guessing how do I fix it? If I am just dumb let me know that too and why. Thanks in advance for the help, I just hope someone can solve this for me before I go buy yet another mower.
Yep. I would agree. A restriction in the muffler could definitely cause your scenario.
#5
sgkent
also fuel varnish can cause a valve to stick in a guide. Carbon can also come loose with pieces falling off pistons, heads etc., and lodging a valve open a bit.
Well, I figured I would pop in with an update to my situation.
There was a bent pushrod. Now the question I have is why? The key looked fine for the flywheel so I dont imagine it was a hard stop. Also it still started and ran fairly easily and I cant imagine that kind of bend being able to move up and down... I dont know. My concern is if there is this much damage here is it worth it to keep buying parts or call it quits and get a new mower.
The pushrod bends because the cam tries to push it and the valve does not move
With that amount of wear it was due for a replacement in any case
I always fit two steel ones ( exhaust ones ) when the alloy wears thin
You can slip the steel one in there, adjust the lash & try to turn the engine over by hand
Most likely the inlet will not move
Usually a gentle tap on the end with a small hammer. or hammer & small punch will free it up if it is just a bit of rust from sitting too long
The valves & valve guides are identical dimensions so the inlet & exhaust guides should protrude the exact same amount into the rocker cavity
If not then the guide has sliped due to overheating in the past .
Are the intake push rods aluminum in these? If so I would install the OEM aluminum push rod on the IN side. Makes it a softer sacrificial part just as Briggs does.
To me, overheating caused this. Course all the other issues can stick a valve per say. Rocker arm moved from its position tweaking the angle on the push rod.
Usually you flip the pushrod at major services to spread the wear out at each end.
Having said that I have pulled some engines apart and the pushrod had a wear hole in it
Sure sign that the oil was never changed .
Thanks for all the help. I figured I would pop in and give a final update. I got the new pushrods from Kohler. They came as 2 for a quantity and as far as I can tell the exhaust and intake were the same materials. I got it put together and it ran better but not great. Looking in the exhaust noticed it was getting gummed up so I drilled it and cleaned the spark arrestor. Put some putty on the hole and now it starts and runs like new. Thanks again.
Million dollar question slomo. My best guess is heat. The oil was thin with gas and I'm guessing the heat from that plus the wear from the guide caused it to give up. The exhaust valve was out of spec and the intake was really loose. Maybe the rocker came loose and bound up a little? Really kind of a mystery. No holes worn into the rods so they weren't as bad as what some people found still working?
