why are plugs failing?

rbig · Mar 10, 2005

I've got several mowers with twin cyl engines, as well as a couple with single cyl engines. Seems like I frequently have plugs go bad.

When I pull 'em and look at them, they show pretty normal, and no signs of heavy fouling like you'd expect to see with plugs that quit working. Cleaning the things doesn't seem to help. New plugs get me going again.

What I do is keep a good supply of several changes of each kind of plugs I use on hand. Fortunately, plugs are relatively inexpensive, so it's more of an annoyance than a real problem.

Has anyone else experienced this scenario? I've wondered what is causing the failures.

KENSFM · Mar 10, 2005

What brand of plugs are you using? I have had similar problems with Champion plugs. I always liked Champions, but I think after several buy-outs their quality has gone way down.
Just my opinion.
Ken /forums/images/graemlins/smile.gif

JerryG · Mar 10, 2005

Yes, Champions are a problem especially in small engines. Try a different brand of plugs. I have had the best luck with Autolite, Motorcraft and also some luck with NGK. These will all last better than Champions.

RalphVa · Mar 10, 2005

There was only one brand of plug that would work without missing beyond 4,000 rpm on my Fiat 124 after a couple thousand miles on them. Think the good ones were NGKs. Champion and a couple others would miss. That was back in the days of replacing plugs at 10,000 miles. Only the NGKs would last that long.

Had an Alfa that would burn out points every 2,000 miles because they were misaligned. Eventually put electronic system on it. Would idle like a kitten at 600 rpm, on a 4 cylinder, with the electronic system.

I've only replaced the plug once on my Gravely. Don't remember what one it had and what one I went to. Pretty sure they weren't/aren't Champion. Big thing with some Kohler engines is you can't set the points at spec. Otherwise, they won't close. Have to set them at 0.016" vs. spec of 0.020". Maybe if you set them right at the point where they almost close but spark the gap, maybe the spark generated to the plugs isn't good enough? Could you have the same problem as on Kohler engines and have the gap set just wrong?

Ralph

Chillimau · Mar 10, 2005

I'm with the rest about the Champion plugs. My mower quit one night about dark and all I had was a really ugly made in china plug ( no name on the the plug) out of another mower that was given to me. I pulled the plug out cleaned some of the oil fouling off and installed it. Just for kicks I left the plug in the mower, It has been running for two years in my mower and no telling how long it ran in the first engine it came out of. The Champion plug was about 4 months old. It was supposed to be a new and improved plug.

I don't normally use salvage parts in my stuff but my intentions were just to finish the yard that night and then get a new plug. But the silly mower started better and ran as good as ever with a who knows how old "china" plug.

I don't think I have bought a champion since, I know I bought a NGK for the Chainsaw.