What my spark plugs want to tell me - water damage

[TurboDieselWeasel]

Hi!

Yeah - basically what the thread title says... What do these fellas want to tell me?


Cylinders: 4 - 3 - 2 - 1

I'm especially concerned about A) the rusty bit on 2 & 3 and B) the green-ish colourisation on 2 & 1.

Engine is a 1275cc A-Series w. carb, tuned to MG Metro spec. Plugs are BPR6ES. Engine has done a fair few miles now... Plugs were pulled after a normal drive through town.

Any pointers appreciated! Thanks!

Cheers,
Jan

[elmotheewokking]

Has it stood for a while? When were the plugs last changed?
Oxidisation can do that...

[TurboDieselWeasel]

It's stood over winter,maybe 3-4 months? But it's running since end of March. Plugs are from summer last year,so not 'that' old. I guess they'v done 8 to 10k miles? Car gets run daily for at least 15-20 miles

[elmotheewokking]

It's probably from where they've been sat, copper does turn green when it oxidises... Which from the state of the thread, it definitely has. Was it stood outside by any chance?
Personally, even if it's running ok, I'd change them for peace of mind and check again in a couple of months...

[TurboDieselWeasel]

Yes, it's stood in the carport. Thanks for your opinion! I was planing on changing them soon.

Cheers,
Jan

[rodney]

id change em very soon!,

[TurboDieselWeasel]

Changed the plug today, runs a lot smoother now.

However, cylinder 2 & 3 are down at only 7-7.5 bar (1 & 4 have 10+)... Bummer. I'm going to adjust the valves and try again tomorrow, but I guess the head gasket is a bit knackered...

Oil in the bore doesn't change the compression, so at least I can hope it's not the piston rings

Cheers,
Jan

[murran]

yeah, i was guna say looking at the greyish colour and corrosion of plugs 2+3 they might be burning a touch of coolant.
particullaly no.3.
not really surprised at the lower compression in them two. the valve seats (exhaust esp.) will be pitted and not sealing very well.

[TurboDieselWeasel]

Update: the worst case scenario happend........ Water ran down the bores and wrecked them...




Oh the curse word...

Cheers,
Jan

[bl1300]

Very unlucky their. Is it possible to rebore and fit oversize pistons or is it scrap?

[TurboDieselWeasel]

Rebore yould be possible, sure. But I've got another engine with about a third of the milage ready. So I'll just swap the engine for another one... Still a bit annoying, as I'm not in the mood for oily fingers... ;D

[xbo11ox]

What!!! Where did this water come from! Surely not the coolant.

[murran]

aslong as their not scored etc they look like they'd probable hone up. did you have a look at the valve seats?

if you have another engine then whack that in.

[TurboDieselWeasel]

Jul 6, 2011 21:57:27 GMT xbo11ox said:

What!!! Where did this water come from! Surely not the coolant.

I have no other idea of where it could've come from, as only the inner two cylinders are damaged, right where the gasket looks like it let go (discolouration)?

Jul 7, 2011 1:04:44 GMT murran said:

aslong as their not scored etc they look like they'd probable hone up. did you have a look at the valve seats?

They are too worn out for a re-hone, I guess. There's a feelable ridge on top of the bores where the top piston ring ends... The water marks a feelable as well with the finger nails.

Didn't check the valves - the engine needs to last a couple more miles before it get's it's retirement. No time to swap engines right now... When I have the time, the head gets a rebuild anyway.

Compression went up by 1 bar with a new gasket. That'll do for some more miles...

Thanks everyone!

Cheers,
Jan

[bl1300]

Jul 6, 2011 21:57:27 GMT xbo11ox said:

What!!! Where did this water come from! Surely not the coolant.

Well unless there was water in the fuel, or the car has a water spray fitted coolant is the only thing it can be.

[PhilA]

Looks like it was just a duff old gasket. Did the head clean up okay?

--Phil


*I was going to say at the top that the paint had come off plugs 1 and 2, overspray from BL but eh

[xbo11ox]

I've never heard of a leaky head gasket ending up destroying the bores before.

[akku]

I've seen one kill a head same way though. Gasket failed (or was defective) between 2 pots - no idea how long it had been driven that way - but there was erosion for want of a better word of a passage or channel between the to adjacent cylinders. Darndest thing.

[xbo11ox]

'I woke up with a massive erosion'

[scaryoldcortina]

?