Melted a spark plug on a WOT pull

[awdtalon4451]

What's up guys, did a WOT pull IN 3rd Saturday and tore something up. It went lean (12.8 ) when I let off. It was missing terribly after I let off. Limp home a couple miles and plugged my plugs. All plugs were visually fine and in specs.... Except this one. Never seen this before

 

[awdtalon4451]

Another one

 

[bryanwheat]

What are your a/f ratio's at wot? Was any timing being pulled?

 

[SmalltownDSMer]

You mean that's not what its supposed to look like from the factory?

Haha, 12.8 lean? What does it usually read when you let off?

Jayson

 

[BogusSVO]

Looks like alum splatter on the eletrode.

If you have acess to a borascope you will want to inspect the top edges of the piston in that cylinder.

 

[white92talontsi]

Looks like my spark plug did.

When I tore the engine apart it blew a hole in the side of a MAHLE piston from a fauly injector.

Might want to take BogusSVO's advice and have a look down the offending cylinder.

 

[awdtalon4451]

10.9-11.2 at WOT. I'm sorry I was still half asleep this morning. I saw 25* according to my pocketlogger. It's was the only plug that did this. The others look fine. Here's some other pics of the head valves and pistons.

 

[BogusSVO]

How does the piston look on the exhaust side of the piston?

It also looks like non-stock exhaust valves, I do not see a "6T" on them

Check your fuel injector on that hole also.

Either the valve was not fully seated, if thats the case, it torched the valve removing what is missing.

OR
the valve chipped and then the valve torched.

 

[awdtalon4451]

Yea you might be right cause the last few pulls felt weak above 5k. The cylinder walls look good, no scaring or scoring. What's up with the build up on the bottom of the valves? Some definitely were thicker. Should I work the whole head or just replace the valves?

 

[BogusSVO]

The Intake valves have the "6T" on them so you should be fine there.

The hole with the burnt valve may could be egg shaped , so lapping may not work.

I would have a complete valve job done on the head.

 

[white92talontsi]

Yea you might be right cause the last few pulls felt weak above 5k. The cylinder walls look good, no scaring or scoring. What's up with the build up on the bottom of the valves? Some definitely were thicker. Should I work the whole head or just replace the valves?

The build up is from Oil that was being Burnt in the cylinder.

 

[awdtalon4451]

Well I called the machine shop an they quoted $350 plus parts if it needs them. He's reputable but doesn't that seem a little high?

 

[BogusSVO]

In my area, yours may differ, It would break down like this.

Pressure test $40.00
Valve job $160.00
Surface $50.00
seat labor $10.00

8 Exhaust Valves $80.00
1 seat (part) $6.00

Then sales tax...

If he gave you a break down, that could be helpful.

But since you are right down I-10 from me, I do not see the cost being that much higher than in Pensacola Fla.

 

[awdtalon4451]

Hmm pretty close to it then. I'm contemplating on upgrading springs, retainers and valves. Or at least springs and retainers (for future goals). It would only be an extra 2-3 hundred. What route would you take?

 

[BogusSVO]

Well I figured a guess at the valves as far as pricing so you would have an idea.

You may as well build the head once to allow for HP growth.

So if you have the money you may as well upgrade since the head is off.

 

[Spoolin4Ever]

Well your head looks quite a bit like mine when I burnt a valve. Burning oil causes the carbon build up (and knock), mine was cause valve guides were bad. I got a head from J&C Enterprises on ebay for $320 shipped. A stock build with a one year warranty.