Spark Plug Hole

[eleven_special]

I have been struggling with spark plug ,hole#4.Plug will thread in but binds slightly on its way in.It will tighten yet upper threads are wore to far for compression tester(short adapter).Is it possible to have plug appear tight yet still leak?There appears to be a slight ridge at hole opening as opposed to a "seat" on 1-3 holes.Could this be allowing the gasket on plug to not seat and upon engine warming up create a noise varying with temperature change? I'm grasping at all straws.

[skids]

I think there are compression testers that push into the hole instead of threading in. You may want to consider using a thread chaser of better yet (if needed) a helicoil. There are several helicoil threads in this forum's history.

[Ken Talbot]

Sure sounds to me like you've got a stripped plug hole. Like Skids says, check the tech sections and use the search tool to research helicoil.

[TADracer]

I agree with Ken, sounds like a stripped hole to me.

I know some people say that tightening a plug with a washer should be done by 1/2 turn after the washer contacts the head for a new plug and then 1/4 turn if reinstalling a used plug. This seems rather tight to me. I use 14.5 pounds of torque and get great sealing every time. I also put a small amount of anti-sieze compound on the threads for lubrication.

Hope the helicoil thingy works fer ya.

The torque wrench is your friend.....especially on aluminum threads.

[John]

The voice of experience (add major reverb here)

I had a similar experience a few months ago.
Here is my post on the subject. It worked very well for me.
http://www.xs11.com/forum/showthread...+plug+helicoil

[eleven_special]

I appreciate the responses from all,very much.I don't have a compression tester that is like a rubber cork and it holds in the hole but have heard of them.I did use a thread chaser but long time experience shows this will not put the missing aluminum back in the hole.I definitely will be installing a helicoil and to do so without risk is time consuming,no problem here.While still grasping at straws does anyone think that this bad hole could upon heating up cause a varying noise similar to valve yet changes ,fades,comes back etc??The valves are shimmed to much better than tolerance.

[John]

Combustion pressure could be escaping past the spark plug threads, sounding like a valve ticking.
On the subject of helicoiling the hole, Helicoil brand makes a special insert kit for spark plugs. It is not the same as a regular spring wound insert. I bought mine at an O'Reilly's. It was about $30. If you can, turn the engine over until the exhaust valve is just cracked open, and stick an air hose in the muffler to blow any metal chips back out of the cylinder. Tape off the other muffler to keep the air in the system, and not escaping out the open muffler. You won't need much pressure. I used about 30 psi. If you follow the instructions with the kit, it will work fine,

[skids]

Good clarification on the special insert. I used a shop vac to blow air into the pipe. I always use a little antisieze on spark plug threads now.

Originally posted by John
Helicoil brand makes a special insert kit for spark plugs. It is not the same as a regular spring wound insert. I bought mine at an O'Reilly's. It was about $30. If you can, turn the engine over until the exhaust valve is just cracked open, and stick an air hose in the muffler to blow(snip)

[eleven_special]

I appreciate the thought on the "valve ticking" noise regarding loose spark plug threads.It has had me stymied for a long time.I picked up helicoil equipment from the machinist at work today.The coils he had were short and shorter.Even the longest will never thread the entire depth of the hole.Further he gave me a combination tap/reamer and I fear the reamer won't take that aluminum out big enough.Heli coil calls for a 9/16 " hole.If I do attempt this with the head on I am going to proceed slowly.I am now thinking that it would be pretty hard to beat the job I could do with the head off.Machinist advises .try it with head on.........if it doesn't work..........then take head off.I appreciate all the great posts guys.

[John]

I would strongly recommend using the proper spark plug kit from Helicoil. The one you want is for a 14mm thread. It is a no brainer, especially if you still have a few threads left for the tool to catch and thread itself into the head. Complete instructions come with it. If you need to actually drilll the head, a 5/8" drill bit is needed. Again, don't use the spring wound inserts. Helicoil recommends against it.

[eleven_special]

Thanks John for what I consider to be sound advice.I have a well meaning machinist but I'm not sure he understands that I am trying for a permanent fix.I am going to pick up a kit tommorrow as I hear we have a rainy saturday coming. "no brainer"? LOL You sure know how to put on the pressure . :-)

[John]

eleven _special

Please let us know how the thread repair turned out. I am the only person that I know of that has used the Helicoil product, and I would like to know if you found it as easy to use as I did. Unfortunatly, I didn't have any threads left to use the thread tapping tool in. I had to drill the remains of a spark plug out of the head, but that took out the threads, and I had nothing to work with. Make sure you have some way to blow the chips out of the cylinder, either compressed air in the muffler, with the affected exhaust valve cracked open like I did, or like skids mentioned, a shop vac attachd to the muffler set to 'blow' and not 'suck'. You don't want those aluminum chips in the cylinder. DO NOT open the ehaust valve much at all, as the tool will contact it . You can see the valve if you look down into the spark plug hole. The aluminum chips wouldn't be AS harmful as steel chips, but I don't think they'd do much good either. Good luck, and keep us posted.

[GNEPIG]

I am the only person that I know of that has used the Helicoil product, and I would like to know if you found it as easy to use as I did.

.. i dont remember what the brand name was, but about 15 years ago i used a little kit that i purchased from an auto parts store. it had an insert/sleeve that looked just like a Time-Sert. after drilling and tapping the hole, i put some anti seaze on the plugs threads, screwed the plug into the insert, slobbed some red locktite on the threads of the insert, tightened it into the head and let it sit for a few hours. it worked very well then and is still working today.
..the instructions were very clear and it was a very easy job to do. the tool the kit came with, had a counter sink cutter on it, so the flaired portion of the insert would sit level in the top of the head.. i dont remember how much it cost then, but the kit was not very expensive.. i think this sounds very close to what John is talking about.