Mercury Optimax Broken spark plug threads?

[cwozfishing]

32C1D8CF-B8D1-4728-85ED-841E938C08C4.jpegMotor: 2000 mercury 150 hp Optimax
serial number: OT143550


Upon removing my spark plugs today, I noticed cylinder #3 threads appears to have a piece missing. Threads appear to be missing from the cylinder head, spark plug itself is intact. Have not changed plugs in a couple years so has probably been this way for quite some time. Is this something to be concerned about?

[JOE54]

yes sir ,remove /replace cyl head inspect cyl for damages ////// please use v6 forum one more down list for yo mtr good luck JOE

[EuropeanAM]

DEFINITELY do not start the engine again- get that head removed to determine whether simply replacing the head will resolve the problem, or whether there is deeper/further damage present.

Moving thread to the 2.5L forum for you.

[blackboat]

If it is determined that the threads are simply stripped and you find no other cause other than a cross threaded plug or corrosion,etc...You might look into a Time Cert spark plug thread repair kit. Although I have not used one in this particular case,the thread repairs I have done have turned out excellent. It is permanent and actually better than the original threads.

[EuropeanAM]

^^^ Provided the parent material is still present, AND that you have a threading tool with a small enough head to permit it's use at this plug angle, this option can work.

I've done a few dozen of them over the years- BUT you must be very careful to remain dead-on the correct angle (you have about 1- 1.5 degrees wiggle room, get outside that and you'll probably destroy the combustion chamber side).

Should ONLY be attempted with the Cylinder Head removed.

[cwozfishing]

Update: I had to have the cylinder head replaced. My mechanic wasn't unable to find the broken piece, so assuming it worked its way out of the engine. He did however get me a picture of cylinder 6 on the engine that he said looked a little rough. I wanted to see if anyone on here can give me an opinion on it. All cylinders are well within compression specs, so I'm not thinking I need to be concerned at this time.
Cyliner 6 resize.jpeg

[JOE54]

smart replacing , seen much worse run a long time

[lpugh]

Update: I had to have the cylinder head replaced. My mechanic wasn't unable to find the broken piece, so assuming it worked its way out of the engine. He did however get me a picture of cylinder 6 on the engine that he said looked a little rough. I wanted to see if anyone on here can give me an opinion on it. All cylinders are well within compression specs, so I'm not thinking I need to be concerned at this time.


Cyliner 6 resize.jpeg

Quick kleen in every tank as well as premium plus at 150 to one probably would have prevented that

[EuropeanAM]

I would like to see a more direct view of the ENTIRE piston crown for #6. If part of the crown is gone (which is what it LOOKS like right at the left lower edge), that engine needs to come down for repair.

[lpugh]

Damn I missed that Don, I think you are correct. Looks almost like detonation damage!

[JOE54]

but none on exhaust side ????? usually first for detonation wouldn't you concur doctors ????? pic does make it hard to see

[lpugh]

Yes sir

[EuropeanAM]

but none on exhaust side ????? usually first for detonation wouldn't you concur doctors ????? pic does make it hard to see

It's been that way for a while, I'd bet.