Oil where spark plug enters head

[what2do]

So, I've got a fair bit of 'wetting' around the base of the plug. It's evident that it's coming from within the bore but what would cause this to occur?

[what2do]

This may be the correct image.

[kevtherev]

Plug leaking

Not tight enough
Seal shagged
Stripped threads
Broken plug core.

[itchyfeet]

Plug leaking

Not tight enough
Seal shagged
Stripped threads
Broken plug core.

Even with these things why so much oil in the compression chamber in the first place?
I have had a loose plug before didn't get that.

[what2do]

Plug leaking

Not tight enough
Seal shagged
Stripped threads
Broken plug core.

Plug is tight
I will look at seal
Threads are fine
Core is visibly ok.

So, it looks as though it's down to the seal which is bizarre as I have had a loose plug before now and it didn't become wet around the base.

I'll swap plugs around and see if anything changes.

[kevtherev]

Plug leaking

Not tight enough
Seal shagged
Stripped threads
Broken plug core.

Even with these things why so much oil in the compression chamber in the first place?
I have had a loose plug before didn't get that.

you could argue that a leaky valve guide would trundle oil down and onto the plug
then with a bit of pushing from compresion....

my "wet plug recess" was simply a smidge of grease that melted in the recess

have the plug holes been greased or oiled what2do?

[what2do]

Plug leaking

Not tight enough
Seal shagged
Stripped threads
Broken plug core.

Even with these things why so much oil in the compression chamber in the first place?
I have had a loose plug before didn't get that.

you could argue that a leaky valve guide would trundle oil down and onto the plug
then with a bit of pushing from compresion....

my "wet plug recess" was simply a smidge of grease that melted in the recess

have the plug holes been greased or oiled what2do?

Nope, no oiling or greasing. Cleaned it thoroughly a few months ago and it was soon as oily again. No, it's not migrating from somewhere else either - oh, how I wish that were the case.

[itchyfeet]

you could argue that a leaky valve guide would trundle oil down and onto the plug
then with a bit of pushing from compresion....

My money is on rings, I find if hard to believe that much oil would come through valves but happy to be proved wrong.

Compression is low and quite a bit or variation but witin the vast wear limits VW give you.

You got the compression figures mitch they were written on a post it?

[what2do]

you could argue that a leaky valve guide would trundle oil down and onto the plug
then with a bit of pushing from compresion....

My money is on rings, I find if hard to believe that much oil would come through valves but happy to be proved wrong.

Compression is low and quite a bit or variation but witin the vast wear limits VW give you.

You got the compression figures mitch they were written on a post it?

Here you go, cyl 1: 10 bar, 2: 8.75 bar, 3: 9 bar, 4: 11 bar.

The wetting is around the plug nearest to the front on the n/s.

[itchyfeet]

Here you go, cyl 1: 10 bar, 2: 8.75 bar, 3: 9 bar, 4: 11 bar.

The wetting is around the plug nearest to the front on the n/s.

Wet around No1 which has good compression, you may think indicates rings are good.
A test for ring failure when you have low compression, is to put oil in the cylinder, increased compression indicates rings are shot.

Is 4 oily plug too?

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DG is 10-13bar new, 3 bar variation limit, 8 bar min limit

[what2do]

Performance has dropped off a lot since we took those figures, I'll try and do them again but I'm afraid the results will shock me!

[kevtherev]

I stand by my suggestion.
and I think it's no.1 inlet.

those erratic figures read like non sealing valve seat figures to me.

[itchyfeet]

Only one way to prove it, off with his head

[what2do]

Only one way to prove it, off with his head

Is it worth doing a leak down test to establish what that the problem is?

[itchyfeet]

Why bother if the valve guides are that shagged it will be very clear, if the are not then must be rings.

I suppose you should check your oil breather tower isn't blocked if the crankcase can't breathe it may, I suppose, cause problems where there is air flow via worn valve guides which moves oil with it.