Murray 425007x92a Spark Plug issue

Nissannismoz

Nissannismoz

Forum Newbie
Hello, I finally got my mower up and running, but there's a catch.
I need to know if its possible to put the spark plug in too deep? If I put it in, almost all the way, the spark plug gets smacked, and it closes the gap on it.
As far as I can tell, this is the correct spark plug for this mower, it ran just fine until I took it out and put it back in. I only took it out to clean it from where it had a flooding issue - which is now resolved.
But could I have put the spark plug in too deep?
I put a new plug in, this time a E3 plug (the E3 3.20) because it says its compatible with the RC12YC plug. The plug that was in it was the same length and all, put it in, and bam, the gap gets closed on this new plug too!
So I put it in half way, and it runs like a dream - BUT I know this cant be safe or right. I'd almost think the plug is too long, and incorrect, BUT that's what the mower calls for!
A Murray part #5066 seems to translate over to a RC12YC plug.
This is a 17HP B&S I/C motor with OHV.

Please help! I'm scared to put this plug back in all the way for the fear of damaging the piston. But I also don't want to run it with the plug half in, either.
Thanks!
 
The plugs you mention do appear to cross reference, but the question is whether or not that's the right part to begin with. Since the Murray manual doesn't cover the engine, we'll need to know exactly which engine you have. There should be a sticker on it that tells the model # etc.
 
Darryl G said:
The plugs you mention do appear to cross reference, but the question is whether or not that's the right part to begin with. Since the Murray manual doesn't cover the engine, we'll need to know exactly which engine you have. There should be a sticker on it that tells the model # etc.
Click to expand...

Looks like it says model: 313707 type: 0126-E1
 
Well, that's interesting. It appears that RC12YC is the right plug and that the E3 3.20 is a direct replacement for it. So the gasket is on the plug, the metal washer at the base of it? Your piston should not be hitting it the plug!

Your issue is beyond me at this point. I was pretty sure I was going to find that you had the wrong plug. Hopefully one of the top-notch mechanics who frequent here will have an explanation/solution.
 
I suspect that something is stuck to the top of the piston in the area of the spark plug gap. Sometimes when you remove the plug or have has in cylinder issues things can break loose and cause issues.
 
Find top dead center and measure depth to piston crown with a stick (wood or plastic)
into plug hole and compare to plug length/reach.
 
Yeah this is a head scratcher, the ( RC12YC ) is what's called for ..PLUG CHART.PNG

I use this plug in my 17.5 HP & my 21 HP Briggs, the only time I've seen this issue, is the changing of internal parts,

Con rod, piston, head-gasket-(thinner or grooved for steel o-ring) , cylinder change (deck clearance shaved), or valve train components, ( including push-rods) changed, BUT I'm figuring NONE of THAT was done, a correct plug SHOULD have the proper clearance and NORMALLY, clears the piston & valves without a problem, I would think you would strip the threads if you over-tightened too much, unless the plug-hole had been stripped, and repaired with a Heli-coil, which IS possible, and that the thread-INSERT, was NOT installed properly, and it slipped into it's bore, from over-tightening (ie.) as you thread the plug in it sort of locks on to the Heli-coil then BOTH screw down into the head, I think you MAY have to remove the head, screw the plug in, and take a look-see. ..... :confused2:
 
Did the washer (spark plug seal) come off when you took it out/cleaned it/replaced it...? if not try replacing it with a RJ12YC which is 9mm shorter and see...!
 
Last edited:
Nissannismoz said:
Hello, I finally got my mower up and running, but there's a catch.
I need to know if its possible to put the spark plug in too deep? If I put it in, almost all the way, the spark plug gets smacked, and it closes the gap on it.
As far as I can tell, this is the correct spark plug for this mower, it ran just fine until I took it out and put it back in. I only took it out to clean it from where it had a flooding issue - which is now resolved.
But could I have put the spark plug in too deep?
I put a new plug in, this time a E3 plug (the E3 3.20) because it says its compatible with the RC12YC plug. The plug that was in it was the same length and all, put it in, and bam, the gap gets closed on this new plug too!
So I put it in half way, and it runs like a dream - BUT I know this cant be safe or right. I'd almost think the plug is too long, and incorrect, BUT that's what the mower calls for!
A Murray part #5066 seems to translate over to a RC12YC plug.
This is a 17HP B&S I/C motor with OHV.

Please help! I'm scared to put this plug back in all the way for the fear of damaging the piston. But I also don't want to run it with the plug half in, either.
Thanks!
Click to expand...

What have you done to the mower to "finally get it up & running "
Any engine work ?
 
You must log in or register to reply here.
Back
Top