Destroyed Spark Plug V6 3.4

[airbag]

Hey everyone,

I was changing the plugs on my 99 V6 when to my surprise noticed that the electrodes from the plug were completely destroyed. In addition to the destroyed plug there is what looks like carbon or oil crud build up within spark plug chamber. The coil pack boot had the same crap on it.

I researched it and it saw causes ranging from the top of the piston smacking the plug due to faulty bearings to detonation in the cylinder destroying the plug. Before it sat, I had an injector replaced because it was running pretty crappy.

Can I install another plug?

 

[LittleCaesar]

Just install another plug. If the engine isn't knocking or making some kind of evil sound from that cylinder chamber, you should be OK.

 

[jacknanita55]

Which plug was it? What wad going on before you changed them?

 

[airbag]

Which plug was it? What wad going on before you changed them?

cyl # 1. It was pinging.

 

[jacknanita55]

cyl # 1. It was pinging.

And after you put the new plug in?

 

[LittleCaesar]

I'd say it was denotation. I take it the injector that was replaced was for the #1 cylinder?

Still though, put the plug in and see what occurs.

 

[thebrandon]

If you don't change a plug for a REALLY long time those electrodes wear away. I've never seen one completely gone like that though. I guess it could happen.

How long had it been since the plugs were changed? Might want to do all six while you have everything apart if it's been a while.

 

[JohnMc]

Looks sort of like two things going on.

1) Electrodes broken off is probably due to high combustion temps or detonation, which could be caused by a bad injector making that cylinder run lean for prolonged periods of time. This is a bit hard on a normally aspirated motor (and will really blow stuff up fast with boost, lol), but there probably isn't anything serious to worry about. Since the center electrode and the insulator isn't damaged, you can tell nothing was smacking the plug itself.

2) All that soot makes it look like the previous plug wasn't installed properly, and some combustion gasses were leaking out past the threads and the crush washer. It might be a good idea to get a thread chaser and clean threads up before installing a new plug. Aluminum heads are always just looking for any reason to strip threads out, being gunked up with carbon soot is good enough.

 

[airbag]

Looks sort of like two things going on.

1) Electrodes broken off is probably due to high combustion temps or detonation, which could be caused by a bad injector making that cylinder run lean for prolonged periods of time. This is a bit hard on a normally aspirated motor (and will really blow stuff up fast with boost, lol), but there probably isn't anything serious to worry about. Since the center electrode and the insulator isn't damaged, you can tell nothing was smacking the plug itself.

2) All that soot makes it look like the previous plug wasn't installed properly, and some combustion gasses were leaking out past the threads and the crush washer. It might be a good idea to get a thread chaser and clean threads up before installing a new plug. Aluminum heads are always just looking for any reason to strip threads out, being gunked up with carbon soot is good enough.

I dont remember which injector I had replaced prior to parking it for a couple years but its extremely likely thats what caused the detonation because it was running sort of crappy after that. I'm going to install the plug and see what happens. Thanks for explaining this!

 

[gamefreakgc]

That spark plug tube is dirty, as in really dirty. I'm also thinking it was not installed correctly the last time, or that engine has a history you don't know about.

Why not replace all 6? Or are the rest in good shape?

 

[28petey]

Just install another plug. If the engine isn't knocking or making some kind of evil sound from that cylinder chamber, you should be OK.

What if you still get a random metal to metal noice and plug keeps getting damaged?

 

[brillo_76]

What kind of plug are you using? Is it the correct length? The 5VZ-FE is a non interference engine. So it wont hit. The only way that could happen is if its a longer plug then stock that i am aware of. I had an electrode break off from not being changed by a previous owner. I never had anything hit though. If the correct plug. The only other thing I can think of is someone shaved the head way too much making it an interference engine. :/ This is definitely a new one..:O

 

[phattyduck]

What if you still get a random metal to metal noice and plug keeps getting damaged?

Get a bore scope and see what sort of evil is in that cylinder... And you likely have a pretty majorly damaged engine.

-Charlie

 

[brillo_76]

Get a bore scope and see what sort of evil is in that cylinder... And you likely have a pretty majorly damaged engine.

-Charlie

I don't know how that can even occur...Something is definitely hitting those plugs and I dont think Toyota made a pile of plugs that had 2 grounds waste spark systems. So I don't think the poster has longer plugs in. I was at a loss never seen that come out of 5VZ-FE anywhere in over 10 years of having them around... However, someone may have out there in the world.

 

[brillo_76]

What if you still get a random metal to metal noice and plug keeps getting damaged?

You have any compression in that cylinder that is doing that to the plugs?

 

[nissanh]

Get a bore scope and see what sort of evil is in that cylinder... And you likely have a pretty majorly damaged engine.

-Charlie

Exactly! I think those plugs are made in China. For an experiment (to rule out excessive heating/lean conditions in the engine).. throw one in the oven and check at what temp it starts melting to eliminate excessive overheating. I once overheated my prizm car's engine to a point it melted the upper radiator tank and heater core welds, but the spark plugs were intact!

 

[Hungryhawk]

I would bore camera inspect inside plug hole. Compare to other plug holes. Then make sure all 6 new plugs screw into head properly before tightning with torque wrench.
Plugs do fail on their own. Not often, but it happens. Also could be last plug change that plug was somehow skipped?
I purchased on Amazon a very useful inspection camera about dia of a pencil. Also 15 feet long.
I use it looking into walls , ducts and water valves so far. Cost about $90.

 

[Pyral]

What if you still get a random metal to metal noice and plug keeps getting damaged?

That's amazing, not in a good way. I've never seen a plug get smushed like that, but whenever it does it means the piston somehow hit it. Usually the plug is much worse off than that, and it'd be hard to remove because it messed up the threads.

I've heard of people getting plugs that fit but extended too far into the engine and came into contact with the piston. I agree with everyone else, look at it with a bore scope.

You at best dented the piston, at worst you cracked the piston or bent the connecting rod. Bad times either way.

 

[Malcolm99]

If isn't the incorrect length plug than there is only one way a piston can hit the plug, broken connecting rod and a piston floating around in there periodically getting hammered by the broken connecting rod sending it upwards to meet the plugs and valves.

 

[clearock]

Doesn't look like the plug is hitting or being hit, it looks like melting from lean condition, [MENTION=71960]JohnMc[/MENTION] answered the issue on the 1st page IMO, i'd check the rubber intake boot that hooks to the TB for tears that are creating a massive air to fuel issue because it's after the MAF. If addressed in a timely manner the engine should be fine.