On the 2nd lap of a race down at Buttonwillow last weekend the Spark plug in Cyl. number 2 shot out of the cylinder with enough force to destroy the coil and seriously dent the hood (I guess there is a good reason to run the coil cover).

Anyhow, long story short--it appears from the 'smear' pattern (anti-sieze thread compound smear) on the NEW plug that only the bottom three threads are still on the head. I've sourced a new (used) head as I don't want to go the helicoil route.

Few questions:
Is there a DIY on head removal and replacement I'm missing? I couldn't find one.
The car ran fine after replacing the coil pack and plug, (kept RPMs low on my trip back home), but I'm wondering what are the odds that there's damage to the piston/cylinder.

Additionally, I torqued all the plugs down to 18ft/lb when I replaced the plugs 20k miles ago. WTF? Did one just vibrate loose and blow or did something else perhaps cause this?

My car is SC'd btw, if that makes any difference.

 

There are probably 50 threads about plugs comming out. IMHO They should be checked on a routine basis and torqued to 20lbft rather than the recommended 18lbft. If you have a supercharger you should be checking them a few hundred miles after any change and again every 1000 miles or so for at least 3 times. I also recommend you always use a little neverseize.

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Thanks Sideways....not sure how I missed all those posts from 2001 and 2002! But it seems that nobody had a plug basically explode out of the cylinder, like I did and all my plugs have been tightened to 18lbs prior to it happening. I had zero issues prior to the explosion--no rough idle, no misfiring, no CEL.

In any case...the plug shot out and took a bunch of threads with it. I know the head is bad and I'm not helicoiling it. I've got a used head I'm going to rebuild, but I'm looking for more info on removing / replacing the head and I'm wondering what are the odds that damage was done to the block....the lower portion of the coil pack was pretty toasted, but the spark plug was in pretty good shape.

 

Just out of curiousity, what do you have against helicoils?

 

I don't have anything against 'em--Helicoils have saved my ass many times. But never in an application that was so critical or had to endure so much stress. Additionally, several people have recommended AGAINST them.

With that said, though....I'm at a point where I'm going to miss another two races if I can't get this shit fixed quick. I might consider a helicoil as a temp 2-day track fix. Is there a way to helicoil the head without removing it? Time-Serts, I hear--are a bit better for the application than Helicoils.

 

I've had no trouble doing a helicoil on a spark plug hole before, but granted not in an FI situation. I was just curious if there was a particular issue I wasn't aware of.

I wouldn't do anything with the head on the car simply for fear of getting crap into the combustion chamber. It's pretty much inevitable with a hole directly on top of the head.

 

Put a timesert into your head. They are a sleeve that gest expanded into the hole. Wurth sell a kit which isnt too expensive vs a new head.

Chris.

see www.timesert.com

 

I've got a second head already, btw--but would like to keep the second one as a spare. I checked out timesert and didn't see an S2000 specific kit.

 

Are the AP2 Coil packs the same as AP1? Denso Parts are the same, but Honda Part numbers are different.