ok i have an oc4.... with a gas engine, it has just suddenly started to foul out #1 plug really bad to the point of miss-fireing i changed the plugs and plug wires,,, yet still after running a bit,,, #1 goes again... wondering if i might have a sticking valve? takeing any opinions befor i tear into it...... thanks
Is it fouling from oil or gasoline? If it's oil, it is probably a bad ring of valve guide allowing oil into the cylinder. If it's gasoline it will be all wet - probably from running too rich. A hotter better plug may cure that.
What brand are you using?
What I meant by the plug curring the fouling if it's running too rich, is if it can't be curred by leaning the carb mixture. Some engines just have a tendency to run rich in one cylinder. We have a Bobcat with a Wisconsin V-4 air cooled that runs rich in one cylinder and fouls plugs - but only in that one cylinder.
If you're lucky, it's just stuck rings and something like Alemite CD-2 might cure it -it used to work on my IHC Scout-
If you're really unlucky, you've broken the wrist pin clip and it's making ugly grooves in the cylinder wall, but let's not even think about that, OK?
Check the compression.
Like Blake said, oil fouling is wet, gas fouling is dry.
QuoteLike Blake said, oil fouling is wet, gas fouling is dry
If it's getting too much gasoline, the plugs will be all wet too. Black carbon all over the plug tips is a sign too, but that does not necessarily mean it's fouling plugs - just too rich.
Oil fouling will usually put bunch of thick gooey sooty stuff on the plug electrodes.
well it not really oil fouling,,,,, more like gas and oil mixed,,, like a plug out of a two stroke .i was thinking it had a stuck valve before and was wondering if maybe the valve seal has finally gave up and died,, ok so i'm hopeing for the easyest thing possable...... the little thing was running great and this just started, hope i caught it before any damage was done..
Does it run good for awhile right after you put a new plug in? If so, it does not sound like a valve problem.
You might take a compression test. If squirting a little motor oil down the spark plug hole raises the compression that can be an indication of bad rings.