Oil on spark plugs with pics

Post by **vanzep** » Sat Nov 16, 2013 4:33 pm

I went to redo the rocker cover gasket today and decided i might as well fit new sparkplugs at the same time.
The spark plugs in there wernt that old - I think i changed them when i did the timing belt last year so theyve only been in there for around 5000 miles and 1 track day. I wasnt best pleased to see the condition of the old plugs when i took them out- All 4 had an orange band around the bottom of the ceramic, all 4 had oil around the threads and the plugs on cylinder 1 and 2 had quite a bit more oil on them than 3 and 4.
The contact areas on the plugs had a light greyish/light brown build up.

Ive left the car at my folks overnight so the rocker cover sealant has a chance to set and ive left the spark plugs there as well - so no photos of them today but i will be able to post up some pics tomorrow.

So it looks like oil is passing by the pistons due to wear - question how long can i expect the engine to last and is this linked to the heat build up issue i have due to fouled spark plug(s) meaning mixture isnt burning right and also causing intermittent sluggish power delivery and also friction around worn pistons causing high under bonnet temp.

Any input appreciated as always

mercutio · Post by **mercutio** » Sat Nov 16, 2013 5:26 pm

are you sure its oil coming up rather than coming down the threads of the plug a light brown deposit is what you want on your plugs

CrunchyAdams82 · Post by **CrunchyAdams82** » Sat Nov 16, 2013 5:50 pm

Yeah, this is exactly what I had last week when I changed my rocker gasket - turned out to be the spark plug seals/o-rings. You were involved in that thread too.

Have you checked those?

Same symptoms as mine, and one week later still running fine.

mart609 · Post by **mart609** » Sun Nov 17, 2013 12:17 pm

I was gonna say the saem thing, the O-ring plug seals on the rocker cover have perished?

BlackShadow · Post by **BlackShadow** » Sun Nov 17, 2013 5:54 pm

I had the same problem. My O-rings were leaking badly. Basically the spark plug tubes were starting to fill up. I did an oil change and lost 5L of oil in 2 days. I swapped out the gasket kit and...its been a month since I had to add oil.

BMCC · Post by **BMCC** » Sun Nov 17, 2013 8:18 pm

Light greyish build up is fine.were the plugs wet with oil?

Post by **vanzep** » Sun Nov 17, 2013 9:49 pm

there was no oil at the top of the plugs or in spark plug tubes in the rocker cover but oil on the threads so possibly spark plug o rings - i changed them 3 or 4 months back when i did the rocker cover refurb so i just reused them this time round.
Anyway heres a pic - hopefully will show some detail...doesnt look good to my eye but im no expert

BMCC · Post by **BMCC** » Mon Nov 18, 2013 8:17 am

Nothing much wrong with them plugs possibly the deposits on the nose etc were because you were burning a little oil before would need to see them next to a new plug, see:

http://www.classic-car-magazine.co.uk/a ... chart.html

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Mon Nov 18, 2013 8:54 am

The heat discolouration on the ceramic part (above the thread) looks quite bad on a couple of them, but I've found that can happen with modern plugs. They seem to react much more noticeably for some reason.

BMCC · Post by **BMCC** » Mon Nov 18, 2013 10:09 am

Taken from http://sc-power.co.uk/pages/sc-power-spark-plugs.html:

Corona stain

A brown stain – often mistaken for gas leakage – is sometimes observed in a ring around where the insulator joins the metal shell of the spark plug. This discolouration is generally called Corona Stain and is the result of oil particles present in the air around the engine adhering to the insulator surface.

The Corona Stain is often seen on spark plugs that are installed deep into the engine such as on many four valves per cylinder engine applications. This is because oil particles are not blown away by air circulating around the engine compartment and thus adhere to the insulator surface. It is important to understand that Corona Stain causes no deterioration to the function of the spark plug.