Oil leak around spark plug

[ba123]

It'll be interesting to find out. Doesn't look like valve covers (I see no oil above--doesn't mean it isn't there--have you run your finger above?).

No likely from below, oil generally doesn't move up the side of an engine that much.

Valve guide is certainly possible even though you don't notice smoke...doesn't mean you aren't burning any--could just be a small amount and if it's coming from the exhaust valve guide, you wouldn't necessarily be burning it...right? It's not going into cylinder as much as it would be pushed into your exhaust.

 

[Wild horse 75]

I thought that too, but I have zero smoke coming out exhaust pipes.

You wouldn’t necessarily have smoke in the exhaust. Since it isn’t entering the combustion chamber it doesn’t burn. You can very much so have liquid oil in your exhaust and not see anything on the spark plugs or blue smoke. Since the exhaust valve isn’t in a vacuum they typically only have umbrella seals and those leak all the time.

 

[Broncobowsher]

Bad exhaust valve seals/guides typically show up as a puff of smoke on startup. Running, things are fine. At shut down the oil runs down the guides onto the back of the valves and into any cylinder that has an open exhaust valve or exhaust valve that doesn't seal perfect. At start up it burns off.

 

[Wild horse 75]

Bad exhaust valve seals/guides typically show up as a puff of smoke on startup. Running, things are fine. At shut down the oil runs down the guides onto the back of the valves and into any cylinder that has an open exhaust valve or exhaust valve that doesn't seal perfect. At start up it burns off.

That’s true but if it’s only the one valve the engine would have to stop with that valve open. Plus if it’s only one even if it stopped with that valve open every single time the puff would be so small unless you were standing behind it while it started and were specifically looking for it you would never see it. For what it takes it worth having a look in the port.

 

[73azbronco]

Oil leak on Bronco=feature.

I also vote it's blowing in from something else like the valve cover. Spray area down with brake cleaner, let it sit overnight.

 

[kat]

So update on my oil leak around spark plug. I was able to put the dye in oil and under black light its coming from AROUND the spark plug. Note the engine isn't smoking, idles, and runs fine. Been driving it for a few days now.
Got it to stop leaking by putting a high-pressure A/C o ring (green) around the base of spark plug and BAMMMMM. Stopped leaking. But why is it leaking around the plug?? I have googled this and come up with nothing related to older V8 engines. I do remember some spark plugs would have a metal ring around the base of plug, but these don't and the ones that I replaced didn't have them either.
And no, it's NOT running down off my valve cover gasket. Clean as a whistle.

 

[ba123]

It’s likely getting past your piston rings. Test your compression and if it’s ok and not that much oil, then no worries. Might stop if you drive more.

If it’s not much, then forget about it until it becomes a problem.

 

[Wild horse 75]

Spark plugs are one of two designs. They either seal on a tapered seat or they seal on a metal “gasket”. The two are not interchangeable. Cylinder heads dictate which design plug you use. Neither are designed to stop oil. They are designed to seal against compression. That A/C o-ring is barely a bandaid fix. It will not last in that environment for long. You need to figure out if you’ve got a bad cylinder or a crack in your head causing the leak. Neither is good.

 

[ba123]

Spark plugs are one of two designs. They either seal on a tapered seat or they seal on a metal “gasket”. The two are not interchangeable. Cylinder heads dictate which design plug you use. Neither are designed to stop oil. They are designed to seal against compression. That A/C o-ring is barely a bandaid fix. It will not last in that environment for long. You need to figure out if you’ve got a bad cylinder or a crack in your head causing the leak. Neither is good.

I agree the oring wont last and don’t really get how it’s working at all.

Of the two types, I’d say the metal crush washer would seal better than the metal to metal, but that’s my guess, but right on not interchangeable.

Could also try some thread sealant. Would work better than an oring and should even stay.

 

[Wild horse 75]

Unfortunately there’s no simple fix here. Anything is really just a bandaid. Either you’re getting liquid oil in the combustion chamber in high enough amounts that it isn’t all burning or you’ve got a crack in the head. The oil drain back is right behind that plug so there is lots of oil in that area.

Neither plug seals better than the other. They both do their job sealing the combustion chamber. I would steer clear of any sealant on the threads as that’s where the plug grounds.

 

[kat]

I agree the oring wont last and don’t really get how it’s working at all.

Of the two types, I’d say the metal crush washer would seal better than the metal to metal, but that’s my guess, but right on not interchangeable.

Could also try some thread sealant. Would work better than an oring and should even stay.

I thought of the thread sealant. I do realize that a AC Oring wont last long, but I was at the end of my rope and thought why not try it. I've put 60 highway miles (high RPM) on it since and not leaking yet. The weather is so nice right now with my doors off and want to enjoy while I can. Gonna keep an eye on it this week while I drive it back and forth to work and see what it does.
The engine is a crate with maybe 40k on it, I did think maybe the rings moved or something, but she idles and runs so great, no overheating, no water in oil, no smoke makes me think its not a crack in head. But I've been wrong before.

 

[kat]

Unfortunately there’s no simple fix here. Anything is really just a bandaid. Either you’re getting liquid oil in the combustion chamber in high enough amounts that it isn’t all burning or you’ve got a crack in the head. The oil drain back is right behind that plug so there is lots of oil in that area.

When you say 'behind' do you mean towards the rear of engine? The oil leak as you can tell by pics isn't terrible but enough to irritate me.

 

[Wild horse 75]

When you say 'behind' do you mean towards the rear of engine? The oil leak as you can tell by pics isn't terrible but enough to irritate me.

The front and rear of the cylinder heads are cast with a passage that drains the oil back down into the oil pan right in that corner. It’s literally right above the head bolt.

 

[kat]

The front and rear of the cylinder heads are cast with a passage that drains the oil back down into the oil pan right in that corner. It’s literally right above the head bolt.

That is where I was thinking it was at. I'm going to try to do a compression test on it this weekend and compare it to another cylinder. It just acts so weird, never seen anything like this. It seems to leak when driving down road so initially I thought it was coming from somewhere else and settleing in the spark plug hole. But maybe higher revs is what causing it to leak.

 

[kat]

Was able to do a compression test on a few of my cylinders over the weekend, 120# on the oily cylinder and 120# on a couple other cylinders. After driving it all week the AC o ring still holding up.

 

[ba123]

Well at least that’s good use of those extra orings!