Spark plug diagnosis

[BobsYourUncle]

I'm after some input on the condition of my spark plugs (photo attached). My conclusion is the fuel mixture is too rich, and there's some oil getting in there, but I'm a novice, so some expert opinions would be helpful 

[Scoota G]

Yep that's what mine looked like before i rebuilt the motor. All the top rings were broken. Have you done a compression test. I used to have to change plug 5 and 6 every few weeks.

[acf321]

Agree with Scoot. I am not a mechanic, but have some experience with these things. From my understanding, the best colour for your plugs is straw colour or slightly darker. These plugs are showing signs of oil, which is either warn rings, valve seals or both, and probably too much fuel. If you lean the carbs out, some of the mess might disappear, but this could be at the risk of cooking a valve or two. I would get the carbs checked for accurate setting, and maybe try an oil additive (such as Nulon or STP or other) to plug up the motor a little, or do what I did and go for a rebuild. Best of luck with it.

 

Adam.

[Zedman240®]

One of the of the plugs looks like its soaked in oil; like everyone else has said, might be time for a rebuild! For now you can try a hotter range plug to help burn of deposits but that is just a temp thing.

[Wayne G]

That looks like unburnt oil as opposed to fuel. What is your oil consumption like? what sort of oil and what colour and when does it smoke? A compression test may help but the accurate test is a leak down test. You are not far from me and I happen to have a leak down tester. PM me.

 

Alternatively do a compression test and record results then inject some oil, about 50ml, and redo compression test. Inject the oil into one cylinder and then test that cylinder and repeat with the next cylinder, do not inject all cylinders and then test because that is very messy! If there is a large improvement in result then your piston rings not sealing well, if not then oil coming in some other way ie diluted in sump, valve stem seals, crankcase ventilation etc.

[dazzed]

I'm after some input on the condition of my spark plugs (photo attached). My conclusion is the fuel mixture is too rich, and there's some oil getting in there, but I'm a novice, so some expert opinions would be helpful 

looking at 2 plugs isnt as good a reference as looking at them all , but just looking at those 2 yes i say its running a tadd too rich, if it was idling for a while before you removed those plugs it could change things also , i go with your first diagnosis bobs your uncle cheers.

[BobsYourUncle]

Thanks everyone - these plugs are from cylinders 5 and 6 (I think that's right, the 2 closest to the firewall). All plugs looked like this, except cylinder 1, which to me looked normal. I think I'll do a compression test - I've been looking for a reason to buy a compression tester for a while .

 

I hardly ever drive the car at the moment - It had probably been 2-3 weeks since the engine was last started when I took that photo. What difference will running the car make? I would've thought if oil was getting in, it'd get worse by running the engine?

 

As I don't drive it much, I don't really have a good figure for oil consumption - it is low at the moment though (as is the coolant - hope I don't have a cracked head...)

 

Thanks for the offer Wayne - I'll do a compression test first, I don't really want to drive the car if I can avoid it until I can rule out any serious problems...

[peter t]

Does this help. Also drop a can of STP into it for the time being.

[chris240]

try this also..talks about difference in plugs.

 

http://www.viczcar.com/forum/index.php/topic,6631.0.html

[ozconnection]

Yes, they might be oily, but get your mixtures right first.

 

You will burn oil when your mixtures are very rich. The fuel saturated mixture that enters the cylinders washes off the oil that is there for lubrication and burns on the plugs. The oil itself gets contaminated with the extra fuel too, diluting the oil and makes it easier for it to get past the oil control rings.

 

A easily fixed situation that can mimic a much worse engine condition (that you probably don't have). Replace your oil and filter ASAP. Sort the mixtures first.

 

Good luck. 

 

 

[BobsYourUncle]

I posted some of this in my project thread, but I thought I should update this for posterity.

 

I did a compression test, which showed 165-170psi for all cylinders. Had a fiddle with my carbies, it seems they were running quite rich. I'm going to adjust the mixture (bought a colortune), and change the plugs and oil and see how it goes.

 

I took the airbox off, and the gauze where the pipe from the top of the rocker cover (some sort of breather?) joins was clogged up, so I cleaned that.

 

edit: And i think this topic should probably be in the engine forum, whoops...