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WakeWorld Discussion Board » >> Boats, Accessories & Tow Vehicles Archive » Archive through April 01, 2004 » Spark plug break « Previous Next »
By Matt Stark (starky44) on Tuesday, February 24, 2004 - 5:33 am:    Edit Post Delete Post
I winterized my boat and found one of my spark plugs was missing half of the ceramic center and the metal post was gone that run up the center. Will this just burn up inside of the piston or is it sitting on top of the piston head scratching the cylinder walls?
By Stan Tannner (sbt3) on Tuesday, February 24, 2004 - 5:36 am:    Edit Post Delete Post
It won't burn up in the cylinder that is for sure. If you have been running it like this it probably damaged the piston and cylinder. You may have gotten lucky and had it go out the exhuast valve. If you broke it during the removal of the plug I definetly wouldn't take any chances. I would pull the head of and make sure it is out of there.
By thomas ryan (g3revenge) on Tuesday, February 24, 2004 - 5:48 am:    Edit Post Delete Post
if it fell in the cylinder, do as stan said and pull the head off. if you ran it that way, it ain't going to be pretty.

if the head (wire end) of the plug broke, just replace them. i break them all the time if i am using a crappy socket.

By Peter Chandler (peter_c) on Tuesday, February 24, 2004 - 8:47 am:    Edit Post Delete Post
Very common problem, often caused by pinging or cheap plugs...Champions? Most likely it went out the exhaust valve, but a boroscope should be able to tell you if it is still in there. I have yet to see one damage an engine but...there could be a first.
By Rod McInnis (rodmcinnis) on Wednesday, February 25, 2004 - 7:21 pm:    Edit Post Delete Post
I am surprised that you discovered this during winterizing. I am also surprised that you are winterizing in February. Where do you live?

When that spark plug broke it would have certainly killed that cylinder, which would be a loss of a little more than 1/8 of your horsepower. I would have thought that would be noticable by itself. It would also impact idle, making it very rough and likely to stall. Starting might have gotten a little harder as well.

I have never had a spark plug break off inside a cylinder before, but I have sucked small object down the intake manifold. It tends to really mess up the engine. If it is still in there, I wouldn't even consider trying to run the engine any more. You could turn a medium rebuild job into a hopeless pile of junk.

As Stan said, it is possible that it broke in the process of removing the plug (I am assuming that you removed the plugs as part of the winterizing). If that is the case, then no damage will have been done, but you need to get the missing parts out, which won't be easy. I might try connecting a vacuum cleaner to a hose small enough to fit through the spark plug hole and seeing if I could suck it up that way. If not, you may have to pull the cylinder head.


By Matt Stark (starky44) on Wednesday, February 25, 2004 - 8:19 pm:    Edit Post Delete Post
I'm from Iowa. We found this plug about 3 months ago and it was all black and worn as it was still firing? Even where the break was, it was dark black. It must have had happened some time in the summer. The weird thing is, is the boat runs + starts great? We never noticed anything? We tried to do the vacuum thing with a small tube and we got nothing out. We are going to try to get a flash light or bore light and try to see the piston head or cylinder walls. I've heard a few different responses, some say it might be alright, some say your engine is ruined?
By Stan Tannner (sbt3) on Thursday, February 26, 2004 - 5:48 am:    Edit Post Delete Post
If the engine is running ok then chances are it is fine. I would do a compression check to make sure that it didn't damage the piston or rings. Also as Peter stated try looking in the cylinder to see if you can see any physical damage or scoring of the cyclinder walls. Sounds like you probably got lucky and the parts went out the exhaust valve.
By Matt Stark (starky44) on Thursday, February 26, 2004 - 5:59 am:    Edit Post Delete Post
That is the plan, is to do a compression check, try to see in the spark plug hole, and try to vacuum it out one more time. I hope that, that will all check out ok. Thanks everyone for the help!
By thomas ryan (g3revenge) on Thursday, February 26, 2004 - 6:26 am:    Edit Post Delete Post
if you take the rocker off the exhaust valve, it might blow it out the spark plug hole. just an idea.

i would still pull the head to check the cylinder walls.

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