Spark plugs binding

[Gozills]

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 its your boat and wallet-knock yourself out! U have likely created a new non original thread path forcing steel plugs through aluminum. As i posted before the hard steel plud will not show damage, the soft aluminum head will-best case plugs will leak compression now-worst case your plugs will eject through your hatch at the most inopportune moment. Best of luck to u!

 

[Gozills]

And now back to placing the never seize on the plugs , I do that before I ever take a new engine to the water pull the plugs and also coat the coil boots with dialectic grease and I don't use a torque wrench on the plugs either

NGK does not recommend never seize on their plugs-they have a factory coating to prevent corrosion

 

[Brad460]

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.

I just don’t think your jet boat engine is a place to “learn” how to work on engines. Do you have any friends who are competent mechanics? True you don’t need a “boat mechanic “, it’s just an engine.

Anyways, if you proceed, get in there with the borescope and look for damage. More than likely the piece went out the exhaust. Worst case it got stuck in between the exhaust vale face and exhaust seat or bounced around on the combustion area and dinged up the top of the piston and head.

Let us know what you find.

 

[WREKS]

@Brad460 If the ground electrode is trapped in the exhaust valve, that cylinder should not pass a compression test. What say you?

 

[Brad460]

@Brad460 If the ground electrode is trapped in the exhaust valve, that cylinder should not pass a compression test. What say you?

Yes, the leakage past the exhaust valve on the compression stroke will lower compression. That’s probably a good idea (and easy) to check compression...

 

[pcriley]

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).

You probably won't. The spark plug threads are steel and the heads are aluminum. The spark plug threads will damage the head, and not the other way around.

Learning by doing is fine, just be cognizant of the risks. The risk in this case is trashing an engine and/or head so you need to be comfortable with that before proceeding with the work yourself. To be frank, at this point an inspection with the head removed is more than warranted, in my opinion. With the head removed it should be relatively cheap for a machine shop to install a helicoil in the questionable plug hole, which is the right permanent fix.

 

[WREKS]

You probably won't. The spark plug threads are steel and the heads are aluminum. The spark plug threads will damage the head, and not the other way around.

Learning by doing is fine, just be cognizant of the risks. The risk in this case is trashing an engine and/or head so you need to be comfortable with that before proceeding with the work yourself. To be frank, at this point an inspection with the head removed is more than warranted, in my opinion. With the head removed it should be relatively cheap for a machine shop to install a helicoil in the questionable plug hole, which is the right permanent fix.

@pcriley I have never cross threaded a bolt by inserting it by hand and then tightening it 90 degrees. However, your warning caution is so important here because: @WilCo The timing chain was replaced. Why? What happened? There are more questions here.

 

[tdonoughue]

I have cross threaded a bolt by hand (especially where the nut maybe had prior damage), but plugs have long threads and a distance down in the engine, which for me usually self-centers them. And they have always gone in very easily. No force against the twist at all.

Even at that, cross threading two? Just strikes me as unlikely. Not impossible, but unlikely.

Could there have been something on the plugs? Or could the gap job have moved the electrodes outward to contact the head threads? That would cause extra force and could break off an electrode... Or could cause cross threading multiple plugs as it pushed the base of the plug over.

At any rate, being where we are, I think I agree at this point that the head should be pulled. First, you have the missing electrode and possible damage to inspect for. Second, a good look at the bottom angle of the threads is in order. The boroscope is a good idea, but may not get the complete picture. Same with the compression test. A good idea, but were it my boat, I would pull the head.

Now, do you want to do that or have a mechanic do it? I have never pulled a head (done about everything else). I do know it is a big job. I will still recommend almost everyone replace his own plugs. But the head? That is a big job... Research and a friend on site may be a good idea if you decide to undertake that one.

 

[WilCo]

Timing chain was replaced because it’s a 2013 AR190 with timing chain issue.
I grew up with a dad working on cars so have some mechanical know how. I do not pretend to know everything by any stretch. I have previously stated I’m going to have a mechanic doublecheck my work. If he recommends pulling the head,we will do that. Again, I do appreciate everyone’s concern. I understand the risk and will have a mechanic look at this.

 

[WilCo]

To close this thread out, mechanic double checked everything. No evidence of cross-threading and no sign of the spark plug piece in any of the cylinders. He did clean all the threads to reduce the likElihood of the plugs binding again near-term. I fired it up at home on the hose and sounds great. I plan to water test later this week but looks like it was a $95 insurance policy to have the mechanic doublecheck everything. Money well spent.

I Am glad nothing was found wrong and I am thankful to have a mechanic that i trust and is reasonably priced. I am also thankful for those that provided input about worst case scenarios. While i could have gotten away without someone double checking my work, it wasn’t worth the risk.
it is hard to accept others questioning your abilities. But I will take the licks, keep on learning, and keep on seeking input on where I can improve. That, in my opinion, is what this forum is all about.

 

[Looper7]

Hey I'm glad it all worked out well now go have some fun on that thing

 

[bronze_10]

Happy this is the ending.... never be too proud to say your in over your head and reach out for help like u did hear.! There is so much knowledge here its crazy!

 

[tdonoughue]

Great result. Congratulations and now go put some hours on those engines!