Club 80-90 Forums

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?

This may be the correct image.

Plug leaking

Not tight enough
Seal shagged
Stripped threads
Broken plug core.

kevtherev wrote: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.

kevtherev wrote: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.

itchyfeet wrote:

kevtherev wrote: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?

kevtherev wrote:

itchyfeet wrote:

kevtherev wrote: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.

kevtherev wrote: 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?

itchyfeet wrote:

kevtherev wrote: 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.

what2do wrote:
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

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!

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.

Only one way to prove it, off with his head

itchyfeet wrote: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?

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.