Hey Guys,

I came off a red light last night driving normal and suddenly I heard a loud pop and the evo started sounding like a out of tune Harley. I pulled over and opened the hood to see that my spark plug cover was cracked to pieces. I pulled on the left most plug wire and the plug came straight out! threads were still in tact. The tip looked fused. Car is at 120k miles and last service was done at 90K when I had the plugs replaced. Any thoughts? Evo is bone stock. Thanks!

 

Picture would be great. If your threads to the plug are fully intact then unfortunately it sounds like the threads on your head are gone now. The question though is what caused it to blow out in the first place and for that I think adding pictures would be a good start.

 

Guess you didn't tighten it enough. Is that the only one plug broken?

 

I added a picture to compare the bad one to the good one on the right. It looks like it bent in the cylinder. When I was removing the plugs None of them felt tight. Not sure if the place I had them replaced at didn't screw them in tight but I want to make sure I don't have another underlying issue before I replace them. Thanks

 

Not sure which one is supposed to be right and left, but I'm guessing top one is the bad, and bottom is good due to the metal in the threads of the top one? Just looking at them I would be worried that the threads inside the head are stripped, may have to helicoil the head to get a new spark plug to torque down. But I'm also a little worried about the bottom one, it appears there is no gap in the picture. Not sure if you did something to it once it was out of the engine, but if it came out of the head looking like that it looks like you're getting some pretty good detonation. If that is the case you may need to take it to a shop or figure out what the cause of the detonation is yourself. Do you have any gauges or logging/monitoring capability?

 

it looks to be that you didnt have them in tight enough, the washer is not properly compressed.
it should look like this
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I had two friend who this happened to as well; both were BBY VIIIs, one stripped the threads completely the other got by.

 

Yup. Looks like those plugs are just finger-snugged.

 

sorry, the top plug is the "good" one. the bottom has came out with zero gap. Could the loose plugs be a possible cause of detonation? I don't have any tools to test with.

 

Loose plugs could effectively change the compression chamber volume so anything could happen.

 

+3...torque 18ft lbs. +/-4

 

With plugs reinstalled have it checked for knock.

 

This is actually the reason why you should use torque wrenches on plugs, when they come loose, they fly out

 

Did you ever figure the situation out?

 

Seeing as I'm going to replace my spark plugs soon, what should proper torque on spark plugs be? Random question!