Murray 425007x92a Spark Plug issue

[Boudreaux In Eunice La.]

Got me curious too........... Heli coil a good possibility on that being the issue ~!~!

 

[Nissannismoz]

Hmm, all this has me worried! It runs like a champ, but all that was done was the carb was removed and replaced the float, the needle and cleaned the bowl out a bit because it was flooding excessively. The issue turned out to be the float was stuck.
Maybe the excessive gas was causing it to bend the tip? I'm scared to put the plug all the way back in, in worries it'll bend again (but this time, with damage.) It didn't look like anything actually came in contact with the plug, no metal on metal at least, but I'll take a picture of the old plug and see what you guys think. Maybe I'm overthinking it and the gas caused a sort of hydrolock and bent the tip on both spark plugs.
...if that's possible.
As far as I'm aware, this motor has never been taken apart, the person I had work on the carb said it looked like the carb had never been removed.
The flooding issue was pretty bad though. To a point the oil was contaminated with fuel so badly it looked as thin as water.
I have ran the mower for about 2 hours in it's current state, mainly just to see how its going to hold up with it's new repairs, and has done well, starts quick and easy, no smoke and oil looks/smells clean and clear.

 

[bertsmobile1]

Fuel will not cause a plug electrode to bend
Only 3 possibilities
1) con rod is loose allowing piston to come closer to the end
2) debris entered the cylinder while the carb was off and that is hitting the electrode ( includes debris working loose )
3) A bent valve / detecthed valve seat is hitting the spark plug.
A head gasket is about $ 10
It takes about 3 hours ( including cleaning ) to replace one.
About 1/2 hour if you do not remove the carb or muffler and just wipe the big bits of dirt off.

OTOH it take about 3 times as long to pull the engine, and replace the con rod.
I know which I would rather do.
You can keep on faffing around trying this measuring that but it is only around 15 bolts to pull the head .
Rotate the engine to TDC on the firing stroke so you dont have to loosen the rockers then all you have to do is remove the rocker cover , the muffler, the manifold to head bolts ( 2 ) and pull the breather tube,
Undo the head bolts, give it a tap and you will know for sure.

 

[Boudreaux In Eunice La.]

Nissan.... Bert Is right on a valve seat may have come loose in the head..........

Did you get a new RC12YC new plug to put into it to make it run like a champagain ?? Or just halfway like you said earlier ???

Another thing, is a valve guide is in the wrong position and a valve rod is bent causing anther issue.....

Take the 4 valve cover bolts off first... Turn the engine by hand with the spark plug out and the plug wire WAY OUT the way.... Don't ask a friend of mine why.... That's a different story on a mower I had to redo almost all the way...It takes a pretty good eye to see if the rocker arms are opening and closing the way they should be....

If not take the push rods out 1 at a time and see if 1 is bent... Make sure 1 at a time, there is an aluminum one and a steel one......


If you need to take the head off take the 8 head bolts off in a criss cross pattern.... The carb intake are 2 bolts and 2 exhaust bolts should come off 1st....

Take the head off and see how the piston looks like IL Engine said something might be in there....

A buddy had a outboard engine in last week and the plug broke in the head and the piston was beat up bad to the point of no return and another piston was shattered and con rod in pieces... Crank was bad... so 7,000 bux later for a new power head he was running in the Gulf of Mexico again.......

Let us know Mon Ami ~!~!

 

[bertsmobile1]

Nissan.... Bert Is right on a valve seat may have come loose in the head..........

Did you get a new RC12YC new plug to put into it to make it run like a champagain ?? Or just halfway like you said earlier ???

Another thing, is a valve guide is in the wrong position and a valve rod is bent causing anther issue.....

Take the 4 valve cover bolts off first... Turn the engine by hand with the spark plug out and the plug wire WAY OUT the way.... Don't ask a friend of mine why.... That's a different story on a mower I had to redo almost all the way...It takes a pretty good eye to see if the rocker arms are opening and closing the way they should be....

If not take the push rods out 1 at a time and see if 1 is bent... Make sure 1 at a time, there is an aluminum one and a steel one......


If you need to take the head off take the 8 head bolts off in a criss cross pattern.... The carb intake are 2 bolts and 2 exhaust bolts should come off 1st....

Take the head off and see how the piston looks like IL Engine said something might be in there....

A buddy had a outboard engine in last week and the plug broke in the head and the piston was beat up bad to the point of no return and another piston was shattered and con rod in pieces... Crank was bad... so 7,000 bux later for a new power head he was running in the Gulf of Mexico again.......

Let us know Mon Ami ~!~!

And take the carb off at the manifold to head bolts cause then you dont have to touch any of the controls just hold it out of the way with a bit of old fence wire or a coat hanger.
This saves a lot of messing around working out what went where.
and I forgot, a new rocker gasket as well.
Put some axel grease on the head side of the rocker gasket so it strips off clean next time.

The longest and hardest part is getting rid of all of the Devils snot ( silicone ) that gets applied by 3rd rate mechanics all over the place like a 5 year old with a jar of peanut butter.