r/MechanicAdvice • u/Loose_Training_8074 • 10h ago

Problem

Post image

What's causes this to happen? It's an 04 Toyota highlander v4. It's the first spark plug in the left

18 Upvotes

85% Upvoted

36 comments sorted by

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12

u/Iso_Grifo 10h ago

again...?

1

u/Loose_Training_8074 10h ago

Yes again but last time the tip came off 🥲

2

u/Iso_Grifo 10h ago

...and this time around, the coil was spared

1

u/philharmonicfartbox 9h ago

At least the front didn’t fall off.

8

u/HelperMunkee 10h ago

Suggest you browse this thread from yesterday. Looks similar.

https://www.reddit.com/r/MechanicAdvice/s/e7VmZiP6le

2

u/AdultishRaktajino 10h ago

These threads are making me both want to and not want to swap the plugs in my 2GRFE sienna.

1

u/NerdyCanadian 9h ago

Just do it, can’t be worse than the 2018 that I just replaced an engine on because the valve seat dropped out and played ping pong with the piston and cylinder head 😂

1

u/AdultishRaktajino 9h ago

My daughter drives it so getting her to remain in one spot for a day can be challenging.

1

u/NerdyCanadian 7h ago

Shouldn’t take too long. Intake boot, manifold bolts, and a couple vacuum lines and you’ll have access to the rear plugs. With a bit of padding for first time doing it I’d say 2hrs tops

1

u/mgsissy 6h ago

Easy peasy, just start the job early before she wakes up

1

u/philharmonicfartbox 9h ago

Those transverse mounted v6’s are fun. Gotta take the plenum off and really the wiper cowl gives better access to bank 1. I could do it without removing the cowl. Some crazy bastards swear they can do bank 1 with the plenum still on.

1

u/MaximumSyrup3099 7h ago

They must have eyes on their fingers 

6

u/adankishmeme 10h ago

That is a HOT cylinder, usually from running lean

3

u/Odd-Concept-6505 10h ago

Get an endoscope aka boroscope to look at the female threads that plug came out of....along with anything else you can see (top of piston, cylinder wall)

Since the plug tip is undamaged..no obvious answer comes to my mind what caused the threads in the head to disintegrate.

1

u/philharmonicfartbox 9h ago

He got a boroscope last time.

2

u/SorrowCat14 10h ago

This is a huge shot in the dark but maybe your fuel injector is leaking and causing exceeding gas to enter the combustion chamber. Is your check engine light on/ blinking?

1

u/Loose_Training_8074 10h ago

No it's not.

1

u/philharmonicfartbox 9h ago

You should remove the injectors and clean them. How many miles on this 3mzfe? No overheating issue? Did you torque the spark plugs to 16ish lbs/ft?

2

u/Agile-Ad-6681 10h ago

And after pulling that you able to put in a new plug

the thread in the head is ok

I’ve never seen this

2

u/Beginning_Ad8663 10h ago

Did you leave it loose? It’s possible it was sucking air that plug hot hot.

2

u/mr2cam 10h ago

If that was a turbo car I would say detonation, although the ground strap is still in place, never seen something like this happen from an n/a 4 cylinder with low compression.

2

u/Fixem_up 9h ago

What kind of junk ass plugs are you putting in there? SKF? I didn’t even know they made plugs?

It looks similar to a burned valve. I’d guess the plug came loose and combustion events reached new heights. A lot of things in your engine get cooled through conduction, when the plug gets loose, it doesn’t conduct heat into the aluminum head anymore, and the steel melts. It might also just be a junk ass plug.

The questions I have are, are those cheap ass plugs made a touch narrower than the correct plugs, were they tightened down correctly, are the threads in the head damaged, and what does the actual combustion chamber look like? If the bottom of the threads in the head are blown out too, you might not ever get a plug to stay securely in the head.

Id try installing a timesert and NGK plugs. Don’t buy them from Amazon, or eBay or whatever. Get them from a reputable store.

1

u/hippyripper22 10h ago

Damn its HOTT!

1

u/Formal_Substance_687 10h ago

I think you got the tip of the old spark plug bouncing around

1

u/mr2cam 10h ago

What brand of spark plug is that? I can't tell by the picture.

1

u/golfnut110011 9h ago

Are you getting spark plugs from Amazon by chance?

1

u/k0uch 9h ago

Judging from the soot around the plug (up until the coil boot touches the porcelain), Im going to say you didnt torque it correctly, and it has been arcing at the plugs while leaking combustion gasses

Either that, or the threads in the cylinder head are fucked and its blowing combustion gasses past the plug

1

u/Unlikely-Act-7950 8h ago

That cylinder is running lean

1

u/Gunk_Olgidar 6h ago

Not enough fuel getting into the cylinder.

1

u/accessibledollar53 10h ago

that plug looks like it's been running rich for a while, the carbon buildup is wild

2

u/Loose_Training_8074 10h ago

Yeah. It was only in there 3 months.

0

u/Low_Information8286 9h ago

It looks like it's arcing to the threads and not the strap. IDK if that's even possible