Spark plugs binding

[WilCo]

Here's an update:
Thread Chasers, at least the one I bought, require a 13/16 deep socket to use. Unfortunatley, a 13/16 deep socket is too wide to fit in the spark plug area.
I decided to not take a chance on the next step (thread repair system), but had talked to a shop that recommended I use one of the old spark plugs, coated in grease, to try to clean out any debris that may be blocking. That seems to have done the trick. I worked it in and out a little bit at a time. While I still needed to use the ratchet to install the new spark plug, it did not require any amount of force at all. Hoping I can use similar lack of force to remove them next time.

Thanks for all the input. I'll upload a picture of the old plugs so you can see the threads all seem to be fine and no corrosion...I have no explanation. The broken diode, on the other hand, may explain why the engine was running rough prior to the swap (at least I hope so - doesn't explain why it only seemed to occur ~6500 rpm).

 

[Pro Build]

Here's an update:
Thread Chasers, at least the one I bought, require a 13/16 deep socket to use. Unfortunatley, a 13/16 deep socket is too wide to fit in the spark plug area.
I decided to not take a chance on the next step (thread repair system), but had talked to a shop that recommended I use one of the old spark plugs, coated in grease, to try to clean out any debris that may be blocking. That seems to have done the trick. I worked it in and out a little bit at a time. While I still needed to use the ratchet to install the new spark plug, it did not require any amount of force at all. Hoping I can use similar lack of force to remove them next time.

Thanks for all the input. I'll upload a picture of the old plugs so you can see the threads all seem to be fine and no corrosion...I have no explanation. The broken diode, on the other hand, may explain why the engine was running rough prior to the swap (at least I hope so - doesn't explain why it only seemed to occur ~6500 rpm).

The gaps on the pictured plugs seem to be way to large.

 

[WilCo]

The gaps on the pictured plugs seem to be way to large.

I used a gap tool, but it’s possible. They were not pregapped.

 

[buckbuck]

Where is the broken piece right now?

 

[bronze_10]

Grease on plug threads? I'm not the mechanical genius that many on here are.. but it does make me think back to a 1970 Chevy c10 a certain 16 year old had who grease his plugs when doing a TUNE UP on his first vehicle..... and few hundred miles later hearing a giant BANG... thud thud thud thud thud..... yeah.... i blew a plug straight outta that pos! Scared me to death! Easy fix... I mean... uh... a friend did that!

 

[Wishfull1]

Unless there is some weird angle / camera defect, those plugs that came out are gapped WAY too much. NGK plugs come gapped pretty darn close to where they need to be and require minimal, if any modification. If the new plug gap is like the old, I don't think it is correct IMHO.

Have a look at Rob's video on changing plugs. You can see the typical gap, where to find the spec. and how to use the gap tool.

 

[bronze_10]

@buckbuck is on it.... you are missing part of one of your plugs!!! Is that down in the cylinder? That would be bad!!

 

[WilCo]

I don’t see the piece. Used a flashlight and tried to look down the hole. Nothing. Blew air down there and nothing came out either. Open to suggestions.

 

[4x15mph]

That missing piece is a concern.... I would consider removing the head. You also don't need to gap the plugs if you buy the correct one's. I think it was good that you didn't go down the path of using the thread chaser.

I think we should all change plugs yearly

 

[bronze_10]

So I bought a bore scope on amazon a while back.. pretty cheap.. it attaches to my phone and has a small cam u can put down in places and look around. They are decently cheap. I would look on amazon and order one with a tiny light on it and get it and visually check the inside of the cylinder through the spark plug hole ... just get one small enough to go through the hole. If no scaring or damage is seen and no parts laying in there then u are prob clear on the missing elctrode... but dont run the engine untill u know. It will knock a hole in your piston amd then u have big boy problems!

 

[pcriley]

I don’t see the piece. Used a flashlight and tried to look down the hole. Nothing. Blew air down there and nothing came out either. Open to suggestions.

I think the electrode is steel so it should be magnetic.

Also, the spark plug gaps in the picture are all over the place. They do look way too big.

 

[Gozills]

I think the electrode is steel so it should be magnetic.

Also, the spark plug gaps in the picture are all over the place. They do look way too big.

This is an example of why mechanical work is not for everyone-a seemingly simple plug change has evolved into who knows what as far as self induced damage and repair.

 

[ZGhost]

I would be very concerned about the part that broke off? If it was me, I would get a magnet stick and see if I can push it thru the hole till it bottoms out and move it around in the hopes of finding the part. I would not run the engine not knowing where this piece is?

anyone sees any issues with running a magnet stick there?

 

[WREKS]

@ZGhost I agree. It would be best if the piston was at BDC to give more room. It may even have been ejected through an exhaust valve? I do not want to think jammed in the valve.

 

[Brad460]

To sum this thread up- the spark plugs were incorrectly gapped, likely cross threaded, the ground electrode has fallen into the cylinder and the engine runs rough.

Whomever caused all this needs to step away from this boat now and find a competent mechanic before it gets any worse..

It’s likely the ground electrode existed out the exhaust, but you need to confirm. Have a mechanic borescope that cylinder for damage.

 

[Looper7]

The amazon bore scope as suggested by @bronze_10 is the safest route if you want to do the work yourself and they are super cheap

 

[WilCo]

While I agree the story does not sound good, I question the comment of needing to step away. I am not trying to be defensive. I am definitely trying to learn and have asked for input. Getting a competent mechanic is input so I accept that.
I have called a mechanic I trust and he is willing to look Monday. I will do that, but I also believe in learning by asking questions and doing things myself.

I dont think the plugs were cross-threaded for a multiple reasons. I inserted them by hand and tightened them by hand easily last plug change. The threads on the old plugs do not show signs of cross threading (please say otherwise if you disagree).

I very well may have incorrectly gapped them last time. I will watch some videos on that to learn. I did use a gap tool and have done this on other vehicles before without issue. This time I bought the pre-gapped plugs so that’s not a concern

I cannot confirm when the plug broke off the electrode. I wish I had inspected each when I removed them, but I didn’t. Lesson learned there. I bought a borescope and will look myself prior to taking the boat to the mechanic.

it is hard to get a boat mechanic. I don’t trust the dealer near me For multiple reasons and that has been backed up by other members that live near me. I called a mechanic others have recommended and spoke at length with him. Unfortunately he no longer works on boats.

so again, I accept your persepctive even if I disagree with it. But I am trying to learn and ask questions to prevent something more catastrophic. So thank you for sharing your recommendation.
Thank you also to all the others that have shared suggestions on things to look out for. Having had a timing chain failure previously and losing my boat for majority of the season, I have no desire to have a messed up engine. I want to and will be careful. That’s why I asked for input.

 

[Looper7]

While I agree the story does not sound good, I question the comment of needing to step away. I am not trying to be defensive. I am definitely trying to learn and have asked for input. Getting a competent mechanic is input so I accept that.
I have called a mechanic I trust and he is willing to look Monday. I will do that, but I also believe in learning by asking questions and doing things myself.

I dont think the plugs were cross-threaded for a multiple reasons. I inserted them by hand and tightened them by hand easily last plug change. The threads on the old plugs do not show signs of cross threading (please say otherwise if you disagree).

I very well may have incorrectly gapped them last time. I will watch some videos on that to learn. I did use a gap tool and have done this on other vehicles before without issue. This time I bought the pre-gapped plugs so that’s not a concern

I cannot confirm when the plug broke off the electrode. I wish I had inspected each when I removed them, but I didn’t. Lesson learned there. I bought a borescope and will look myself prior to taking the boat to the mechanic.

it is hard to get a boat mechanic. I don’t trust the dealer near me For multiple reasons and that has been backed up by other members that live near me. I called a mechanic others have recommended and spoke at length with him. Unfortunately he no longer works on boats.

so again, I accept your persepctive even if I disagree with it. But I am trying to learn and ask questions to prevent something more catastrophic. So thank you for sharing your recommendation.
Thank you also to all the others that have shared suggestions on things to look out for. Having had a timing chain failure previously and losing my boat for majority of the season, I have no desire to have a messed up engine. I want to and will be careful. That’s why I asked for input.

Hey we all make mistakes don't get discouraged it's not like your the first person to have plugs get wonky in an aluminum head. Just be sure you don't have any debris in the cylinders and get that thing back in the water. I know you will never cross thread a sparkplug again not everyone will agree with this but I live by the rule no dry threads so loctite where required and anti seize of you choice everywhere else. And keep doing your own work. Best of luck to you

 

[Liftr]

Nice, well reasoned response.

Some good news is; you don’t need a “boat mechanic” to help you with this episode. Any competent auto, small engine, or equipment service tech can help you out here.

 

[Cobra Jet Steering LLC]

lessons are expensive, so avoid the tuition and learn from other peoples mistakes. My advice for the day.