The spark plug lost its .045 gap

milkyway

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Jul 31, 2004
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535
When I removed the #1 spark plug to detect possible cause of bad engine performance, I noticed that this plug's ground electrode bent down and was now touching the center electrode. The .045 gap was gone. What's the possible cause of this that might be of real concern?

Thanks.
 

Don S

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Re: The spark plug lost its .045 gap

Something hit it, either in the engine or when installing it. Did you drop it then pick it up and not look at it? Being all the way closed, you had to have a dead miss, how long has it been missing?
 

milkyway

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Re: The spark plug lost its .045 gap

Prior to initial use of boat this season, I installed new 8 plugs, then checked engine timing, and this #1 plug did not mess up my timing check. I got correct reading. The engine ran fine until at some point in my return trip, I heard new knocking noises and the engine was kind of struggling. So I could have not accidentally damaged between installation and removal. I must have discovered this problem early June and I saw that plug again today in the garage and has kept me wondering what caused it.
 

freddyray21

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Re: The spark plug lost its .045 gap

I agree with Don. Something had to have hit it like the piston. Could be the wrong plug in it.
 

Bondo

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Re: The spark plug lost its .045 gap

I heard new knocking noises and the engine was kind of struggling.

Ayuh,.......... I guess That could be the Real Issue........
 

milkyway

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Re: The spark plug lost its .045 gap

What could be the real issue that caused the spark plug to deteriorate? Would a bad plug cause the engine to knock and struggle and not vice versa?

Please tell me more in case I need to do more checking as preventive measures. I went out 2 weeks ago and the boat ran OK for 3 nonstop hours.
 

180shabah

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Re: The spark plug lost its .045 gap

The plug didn't deteriorate, it was smashed.
 

Don S

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Re: The spark plug lost its .045 gap

Pull the head off and LOOK.
 

milkyway

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Re: The spark plug lost its .045 gap

Pull the head? I have pulled out my portable head but this head is something I have to read on and learn. I hope this engine takes me to end of September. Easy now, don't worry... Thanks.
 

WAVENBYE2

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Re: The spark plug lost its .045 gap

Put a brand new plug in it, check the gap ,and see if it does it again.
 

RubberFrog

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Apr 9, 2005
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Re: The spark plug lost its .045 gap

And start saving for a new head and piston.
 

capthook

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Re: The spark plug lost its .045 gap

Put a brand new plug in it, check the gap ,and see if it does it again.

Don't do that. You are risking a huge bill of sale. If there is something in there from the carb or something like a bolt it will kill the pistion. Get a magnet and fish around in the cylinder or take the head off and inspect. You may get lucky.
 

dirtyoldman

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Apr 30, 2007
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Re: The spark plug lost its .045 gap

i will do that .

Call a dealer and find out if you have the right plug. It may be too long, and the top of the piston is hitting it.

I think if you run it without checking for damage, you may be loking for a long block soon.
 

Dakota47

Senior Chief Petty Officer
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May 22, 2007
Messages
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Re: The spark plug lost its .045 gap

you can go to napa and get a sparkplug anti fouling ring, its a small ring that screws into the sparkplug hole and then the sparkplug screws into that. it keeps the plug out of the cylinder. keeps them from fouling on a worn engine. it will work for your problem too.(it will keep the plug from hitting anything)
 

Gary H NC

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Re: The spark plug lost its .045 gap

The best thing you can do is pull the head off the engine before you make things worse.I would not even start the engine until i knew what was going on with that cylinder.
Take Dons Advice and have the head removed...;)
 

Dakota47

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May 22, 2007
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Re: The spark plug lost its .045 gap

If you do what i suggested, make sure you do the magnet trick as capt hook said..
 

milkyway

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Jul 31, 2004
Messages
535
Re: The spark plug lost its .045 gap

Madre Mia!!!! This can be something serious, huh? Ok- time to go back to the manual and lean how to remove the head. I know nothing about inside of engines. I see them as washing machines.
 
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