why's no.5 cylinder keep doing this to my plugs???

[wana s' charge stock vt]

just curious to find out why every plug looks like new except no.5 plug. after 2 days of replacing it it will look like this. everyother one looks 100% but no.5 will keep doing the exact same thing to a new plug in a couple of days. exact same burn mark in the exact same spot. replaced that one plug and it done the same thing again within a couple of days.
any one seen it befor or have any idea's??

[mrbeef]

maybe your lead is poked? test the resistance on them

[wana s' charge stock vt]

could very well be. i've just got new leads, but will swap it with different plug and see, cause cant remember if the plug was in befor the new leads or not..

[stockyvrcalais]

keep us posted on this one

[Tree cutter]

There is oil getting in to that cylinder. You could have a leaking valve stem seal or worn rings. If it is valve stem seals you will notice a cloud of blue smoke out the exhaust when you first start it. If it is rings it should puff a bit of blue smoke when you lift your foot off the throttle after a fast run. A compression test will tell you if it is rings also.

[wana s' charge stock vt]

thats not what i wanted to hear. is it possible its a LIM gasket or head gasket???
also- ya seem pretty certain but are ya 100% sure?

[Tree cutter]

I am pretty sure it is oil. Coolant will normally wash the carbon off everything and i can see carbon on the metal part of the plug. Look up reading spark plugs. there should be a few sites with photos and explanations.

[wana s' charge stock vt]

i found one the same after a long time searching 'splash fouling'

Splashed fouling, as shown below, may sometimes occur after a long-delayed tune-up. Here, deposits accumulated after long periods of misfiring or low power operation may be suddenly loosened when normal combustion temperatures are restored after a set of new plugs has been installed. During a high-speed run, these materials shedding off the piston are thrown against the hot insulator surfaces.

How to read your Spark plugs Car & Motorbikes

[Tree cutter]

It does look the same. It will be interesting to see what it looks like after a couple of weeks. Old plugs are a lot easier to read than new ones.

[wana s' charge stock vt]

just found another one too.



Spotting or Splash Deposit Condition
Color: black
Appearance: spots

This is due to "sludge" build up or faulty fuel intake Carbs: Dirty bores, jets, and air intake Fuel Injection: Dirty or faulty injector Time for the fuel system cleaner! Best thing to do is if you have carbs, remove them and perform a clean and adjust (including the float bowl area). If you have FI, remove the injector and clean in solvent,


cant believe how much you can tell about the tune in ya car from reading the plugs. its crazy. AFR at idle, AFR at WOT, timing, temp,hight or low octane,pinging, go's on and on.
and on ..

[Tree cutter]

Yep there is a lot to be found by looking at your spark plugs. I was taught how to jet a carby by looking at the plugs when i was younger. We didnt have air fuel ratio meters once so we just went by the colour of the plugs. Whenever i change a set of plugs i always sit them on the bench in the order they came out in so i can inspect them to see if the engine has any problems. That last photo looks like it is running a bit rich which i suppose sould be caused by a dirty injector that lets fuel dribble out instead of spraying a fine mist.

[acarmody]

When you find the answer give me a bell, I really want to know.




First is after a few weeks, second is after a couple of days, and coincidentally cylinder 5. I'm pretty sure its oil because I'm 99% sure I've seen smoke when I turn car on. I'm going to change the valve stem seal first as they as quite easy and cheap. If its a ring I will be pissed as my engine was rebuilt last year.

Can anyone explain the burn mark?

EDIT: And I've had my injectors professionally cleaned recently.

[delcowizzid]

is yours in cylinder 5 as well right beside the pcv valve in the inlet manifold isnt it

[acarmody]

No joy delcowizzid, I changed that last time I had the had he inlet manifold off.

[shifty6]

so the oil coming through the pcv vavle may just be going straight into that cylinder and burning up on the plug?

[delcowizzid]

could well be

[acarmody]

Any chance mine could well be leaking valve seals? I can change those easily enough.

[wana s' charge stock vt]

acarmody- is yours a l67 too? or ecotec.

[acarmody]

Ecotec, dammit. I could have had a L67 but my decision making process was fundamentally flawed.

[wana s' charge stock vt]

hmm.

just checked mine again then and its got a light brown tinge after 1 day. it dont seem like a chunk of poo is falling off the piston and sticking there like the 'how to read a plug' thing says. its like its slowly being burnt.
.

green said its possibly either spark of fuel. but if ya got your injectors just done it may not be that. how old are ya coils?
i got 2 day old leads too so canceling that out

[acarmody]

I'm going to try changing my leads soon. While mine are only about 3 years old, and a good brand, on two occasions I have had a lead fall off while driving, so change soon.

[wana s' charge stock vt]

are ya coils are still factory ones?
im guna try swapping my coils over tomorrow and see if it changes the cylinder that its happening in.

they're all interchangable and the same arnt they?. apart from numbers on top

[acarmody]

Yep all exactly the same. But I tried swapping the whole coil pack assembly with my parent's VY one and it was exactly the same.

[wana s' charge stock vt]

Yep all exactly the same. But I tried swapping the whole coil pack assembly with my parent's VY one and it was exactly the same.

bitching. so you've got a rebuilt motor,try'd different coils, got good leads, cleanen n tested injectors, new pvc valve, lim gaskets, what else have ya try'd or replaced??, you'll be saving me alot of time i think have you touched the heads or valve stem seals befor?

[acarmody]

Heads were reconditioned and ported for rebuild, but maybe one of the steam seals died prematurely, not like they are an expensive or complex part. Also I've had a compression test and all the cylinders are at 205psi, except number 5 which is at 210psi. So good guess not rings. And I'm sure I've seen smoke before when I initially turn car on, but can't see any when car is running.

Also tried different oils. No joy.