What am I looking at - spark plug hole #1
 

I have been inspecting my cylinders and pistons with a borescope, but when I tried to do #1 (right side front) I saw this.
http://986forum.com/forums/uploads02...1552935952.jpg
Looks like a washer, the hole in the middle is big enough for the plugs electrode to pass. Is this normal?

The rest of the holes look like this, which is what I would expect.
http://986forum.com/forums/uploads02...1552936069.jpg

Left-Over Washer
 

Maybe a washer left over from a home-made spark plug tube removal tool?

The engine was running fine when I removed the spark plug, whatever it is it is solidly held in place.

If you gently feel around with a brochette skewer or something , can you feel the piece?

Looks to me to be an "oil fouled spark plug saver" type of device. The intent was to have a central port (the hole you see) for the spark plug to fire through, but prevent oil scraped from the cylinder walls from reaching the plug.

Yes I did that, I used a metal rod to more than gently explore the surface and the hole... it is solid.

That sounds like an explanation... I was thinking something like that, but more in terms of controlling the spark. If it is what you suggest is this common on Boxsters or Porsches and why only 1 cylinder?

No, they screw in from the outside just like a spark plug. You'd see the hex shaped area where the wrench fits to it just like a spark plug. What he's got there is bizarre looking. It almost looks like a previous plug broke when taking it out and some piece of it was left in there? Damn, I've never seen anything like that.

That is totally bizarre. So that is at the bottom of the threads for the spark plug!? In other words at the top of the cylinder? And the plug you pulled was properly seated and engine running well? That makes no sense. What could that be? And no, it’s not “normal” for a Porsche engine.

Valve spring retainer?
How...?

So odd.
Compression tester that broke off?
Can you measure the depth of the threads and compare to another hole, so we can get an idea how deep it is? I mean, is it bottomed out in the threads? If not, could we assume it's threaded? If so, Google "internal pipe wrench" or "nipple extractor".

Dunno. Weird.

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does a direct light either around the edges or through the center reveal anything? does this move side to side at all? can the borescope fit through the center>

Is it somehow a reflection of the borroacope itself? Odd explanation....but very odd problem.

that's what i was thinking, as you will encounter some of the pistons at TDC.

did you crank the engine and check it again? Could be the piston top?

Well, I'm glad to know that it is not something obvious. Hare are a couple more pictures.

http://986forum.com/forums/uploads02...1553027715.jpg

http://986forum.com/forums/uploads02...1553027765.jpg


Yes it is below the bottom of the threads and yes the plug was properly seated, looks the same as the 5 other plugs in terms of colour and there is no indication that the electrode was touching the "washer", so the "washer" must be well below the bottom of the threads. The hole is too small for the electrode to protrude through it. Yes then engine ran fine, although I only put about 200 miles on it between buying it and putting it away for the winter.

In the above pictures you can see the piston crown through the hole, the pictures in my first post were with the piston at or near the bottom of the stroke... I turned the engine so it is at the top. No the "washer" does not move, the silver ring around the outside edge of the "washer" looks to me like it could be solder or welding.

I think the fact that piston crown is visible eliminates the possibility of it being reflections. I have other pictures, plus what I saw as I moved the borescope around, that leave me certain that that is the piston we are seeing through the hole.

So, one far out explanation that came to my wildly imaginative mind was that someone was strengthening the head... perhaps a crack around the spark plug hole. That seems ridiculous even to me to do that inside the cylinder.
One other interesting fact, when I did the compression test this cylinder was slightly higher (5%) than the others. I imagine having hardware taking up space in the combustion chamber would contribute to that.
It would be very interesting to drop the engine and remove that head... but if it continues to run well I'm not going to do that.
Anyway, the plan is to get it back together and start it. If it still runs like before it will go back on the road. I may keep my eyes open for a good used engine just in case...

EDIT - I just saw Gilles' question... I did pass a steel rod through the hole and it went a couple of inches before hitting the piston, this was when the piston was at the bottom of the stroke.

Could be that that the previous owner installed a 'spark plug extension'..? those things where used to keep the spark plug from getting fouled with excess oil (when a particular cylinder was burning an exesive amount of oil), perhaps one of the old gear heads here remembers them..

If I remember correctly, you were supposed to thread them on the spark plug threads, then you bolt the spark plug on top of it .

EDIT: If you install a plug back on this cylinder and measure the distance (depth) from the tip of the plug to the valve cover, and then do it again with another cylinder you can see if the plug on this particular cylinder sticks out further than the other plugs, then you have an extension..

Not to state the obvious, but I have looked down more spark plug holes than I'd care to think about, and whatever that is, it is not correct and does not belong there. The next question is what do you intend to do about it?

I note that the threads in #1 look much cleaner than the threads in the other hole without the "gizmo", so if we take the theory that it is to stop oil, it appears to have worked...
Never saw anything like it, and now I want to know what it is...

I figured it out!!! It’s a flux capacitor! Cool!

Looks like a conical trim washer to me. :confused: Other than that, nothing to contribute.

We have a winner! As suggested I measured the distance to the top of the plug in cylinder 1 and in cylinder 5 and there is an inch difference. Here is a link where you can see some extensions.
https://www.autozone.com/ignition-tune-up-and-routine-maintenance/spark-plug-non-fouler
Why was it installed? No idea... but if it ain't broke don't fix it. I might mention that I paid $5,000 for this Boxster, so I plan to enjoy it rather than find unnecessary work to do on it.

The coil pack sits 1" proud of the head?
That would not be good.

I was wondering the same thing..:rolleyes:

If this thing is screwed into the cylinder head’s spark plug threads, is there an easy way to unscrew it without removing the head? Seems like it could be risky to try.

Bend the tip of a coat hanger and see if you can get it to move?

Is there a hex end sticking outside the plug hole?

Does it ever blink ??

You really should get that out of there. As mentioned, having the coil pack stick out an inch is not a good thing.

It would seem that I am somewhat cautious about how to handle this anomaly.
My analysis is:
1) the engine ran well as it is.
2) someone made a conscious decision to install the extension for a reason… that I have no way of understanding.
3) simply removing the extension would, I assume, bring me back to the problem that lead to the installation of the extension.
4) so why do anything? At the very best removing the extension could lead to the engine running well… which it does now, but, at worst, it could lead to a problem that means removal of the engine for repair of the original problem.

Here is my latest take on the situation…
I doubt that the original problem was plug fouling, simply because there is no visible evidence (oil or carbon in the extension or different colour of deposits on the spark plug). The only other reason I can think of is that someone damaged the threads in the spark plug hole and installed the extension (perhaps with JB weld or some-such) so that plugs could be changed without further deterioration of the original threads. Remember that this is in the cylinder that is the most difficult to access, so chances of cross-threading are maximized. If this is the case trying to remove the extension would mean having to remove the engine to fix the threads. Perhaps I am wrong, but who wants to take a chance? Not me.

The installation of the coil pack isn’t a problem, I will fabricate spacers so that the mounting screws aren’t putting pressure on the “ears” of the pack. But again there was no problem before.

it's not a head-off job to remove it, but probably a cam cover off job (and all the reqd cam holding tools) unless you got skilz and can dr. longskinnyfinger it out through the little hole in the cam cover. hack way to do a thread repair. first step would be to confirm your thesis - get your borescope in there and try to see the hex head of the anti-fouler. then check to see how the coil pack sits - did you notice it sitting proud when you removed it? then think to yourself - whoever used an anti-fouler for thread repair also had my cam cover off - do i trust any other work he's done? personally,i'd pull the cam cover just to confirm, remove the fouler and repair the thread properly.

edit - i presume it would come out just like a spark plug, so not even a need to remove/inspect cam cover. not sure how hard it would be to put in a helicoil with all that in the way, however (just trying to manage all the shavings) ...

1) So?
2) Probably just a moron.
3) Who says there was ever a problem?
4) If you're going to do something, do it right (also an answer to #3).

Have fun with that. ;)

Before even getting to the coil pack being an inch higher than normal, what about the spark plug not being fully seated in the head? Spark plugs are meant to be threaded all the way into the head, and they have that compression washer and shoulder at the end of the threads to make a tight seal with the cylinder head. Seems like that would be an issue too.