Car not running right. Broken spark plug?

[bmcecosse]

Put one of the other plugs in 2, and take it for decent hard run.if that plug now cleans up and comes out 'grey' ... Then suspect the head gasket leaking water in.

[James k]

It's now got four new plugs in so I'll take a look at them after a good run. Here are the pictures of the old plugs. The one at the bottom was from cylinder one and the one at the top from cylinder two. Would water getting in via a broken head gasket not show up on a compression test? [frame][/frame]

[James k]

This picture better shows what I meant by the body of the bad plug going a dull grey.[frame][/frame]

[panky]

Have you got close up of the electrode on the dodgy plug, to me that looks like it has actually broken off

[drivewasher]

The timing seems to be set correctly now, it's not pinking. It was set correctly before but then the mechanic who did the MOT leaned out the mixture and it started knocking.

If your car used before August 1979 it doesn't need an emissions test that analyzes the exhaust gasses. It should have a VISUAL only check. One at tick over after purging the manifold at 2000rpm for 30 seconds then one while revving to about 2000 rpm if no excess smoke is observed then it's a PASS
There should be NO NEED to alter the mixture

[SteveClem]

I had exactly the same issue with my Austin a few months ago. It was a faulty ( champion) plug that had failed in a very similar way. No problems since with new plugs,and as Panky suggests I kept the 3 survivors as spares. I wonder if there's been a dodgy batch of Champion plugs produced?

[panky]

And keep the dodgy one for your black museum

[bmcecosse]

I would like to see an old plug put in #2 to see if it cleans up.

[James k]

The mixture adjustment wasn't done as part of the MOT, just by the same mechanic. I'll check another plug in there tomorrow to see if it cleans up. I hope the head gasket hasn't gone, I only changed it in November :/ I just got back from a good drive and took the radiator cap off to look for fumes. Vapour was coming out when I removed the cap but vanished after a few seconds and didn't reappear when I revved the engine. There is brown sludge in the radiator cap though.

[panky]

Was there a lot of pressure released when you took the radiator cap off?

[James k]

Not really, no.

[bmcecosse]

Possible the plug wasn' bottomed out' in the head seat? That would allow air in/hot gas to escape and could cause the plug to overheat.......

[James k]

Do you mean the plug might have been loose?

[bmcecosse]

No it may have been tight, but not bottomed out.....

[James k]

What does bottomed out mean?

[grumpydad]

Hi
I dont think you have a head gasket problem
who did you use in Hastings to do the work

[panky]

Not really, no.

If the head gasket was leaking into the water jacket then there would a build up of pressure forcing the water out through the rad cap so most probably it's OK. As had been suggested give the system a good flushing to get rid of the brown sludge and re-fill with anti-freeze - it's not just anti-freeze and not just for winter.

[James k]

What could the brown sludge be? I flushed the system out in November and put antifreeze in. Perhaps I didn't flush it fully enough.

[bmcecosse]

Bottomed out means exactly that - the plug is screwed right down till it bottoms on the copper ring gasket..... If it jams on the thread short of the bottom.....well.......obvious surely...

[panky]

What could the brown sludge be? I flushed the system out in November and put antifreeze in. Perhaps I didn't flush it fully enough.

There's always a bit lurking in the water jacket somewhere if the car has been run on plain water for a while (not in your ownership by the sound of it). I've not tried the dish washer tabs myself but it sounds like a good idea