Whatta car....whatta car! Detail matters!

[liftnot]

After reaching 200k 2 wks ago, now at 203K,:smile: the car suddenly had an exhaust leak coming from the right bank so we figured the exhaust gasket is blown....no big deal.
Babied the car to Ramon, found out it was running on 5.

#5 plug had backed out and made a mess. It was ~100k miles ago in 9/2013 that a typical major maintenance was done not by Ramon nor us. The best WAG was that the crush washer on the plug was tight but not tight enough and over time, it finally backed out and took all the threads with it in the head.

Senor Ramon did a colonoscopy on #5 , decided an insert was the only option so after he lived his life 1/4 mile at a time, it was repaired and running like as if it just had a Prospeed injector upgrade....mo smoother and revs quick with the 21lb Exedy twin carbon. Ready for the Rockies in July

Lesson learned....every detail matters, car has good compression, but it not burning any oil at all. We had a similar case with the rear toe link that was made from alum with no steel inserts, car was good for 2 alignment and was no longer able to hold any settings. Lucky a 4130 toe link was available. If you have the alum variety, start planning. :wink: If you are FI, might be good to ck the plugs if you did not install it yourself.

Contact us for a set of oem exhaust gaskets available for sale.

 

[Old Guy]

Getting away with just an insert in the spark plug hole qualifies as leading the charmed life. It probably was an exhaust 'leak' that you were hearing, just not leaking from where you thought the leak was occurring.

From the remains of the coil nose and the coil base gasket, it seems apparent that really hot combustion products were exiting around the plug (and through the plug?) while the coil was still able to generate a spark. You are lucky that you did not initiate an engine fire. Did the sparkplug center electrode come out with the plug or did it fall down into the cylinder presumably exiting via the exhaust port? If the latter and your compression is good then you are leading the double charmed life.

 

[liftnot]

plug was in pieces and Ramon had to fish them out.....lots of plastic pieces around the plug valley...... did not smell fuel knowing while on 5, the injector still spitting out fuel regardless.....perhaps the cam overlap sucked in by other cylinders???
no fuego..I got very very lucky.

 

[goldNSX]

Lucky owner! The plugs change interval is every 60k miles, not 100k. If the owner doesn't change them the plugs make sure and obvious that they like to be changed.

I've noticed on my other Hondas as well that the plugs like to be checked frequently (every 12.5k miles) as some of them have the urge to unscrew themselves over time (they require less torque to unscrew).

No worries about FI as the recommended interval is much lower like every 25k miles and different plugs are used.

 

[Mac Attack]

I remember when Trev experienced his blown out spark plug. Looking at his thread again it appears that you're at least the third person on Prime to experience a broken spark plug specifically in cylinder #5 :

http://www.nsxprime.com/forum/showthread.php/76731-Hesitation-then-massive-Engine-Vibration-and-Noise-Help!?

 

[liftnot]

Hmmm...3 cases....Trev had a SC. my is near stock. My 1st guess is FI is more likely to have have this problem with higher cyl. pressure and combustion. Or perhaps #5 has a tendency to have a "mystery" higher order/hard to detect natural Hz. regardless of FI or NA at certain rpm??? Not sure if Trev torked his or if that made the difference.

I do know if my engine was FI or highly tuned on a chassis dyno, then I would take it out more often to read to be safe as many tunner like to tune it on the rich side to be "safe". Then this would not have happened.

The insert was $65 and I am glad it was a straight-forward fix and Ramon was competent as always. I got away this time not selling my kidney.

 

[nis350]

I imagine the plug would stay put once the washer is crushed and doesn't take much torque.

the plug was probably hand tight or the installer just forgot to tighten it.

 

[liftnot]

Well...u would think if it was just snug, it wouldn't have taken 100k miles to come apart....the other 5 were tight so the likely culprit is doing the work too quickly but even that is an odd conclusion as it took 5yrs to happen.
What does it take to "unscrew" a plug like this?...who knows....bad vibration?.....resonance? an anomaly nevertheless.

One local 97 NA guy had a blown head gasket not from tracking....that is also uncommon but unexpected things happen...such is life. I am sure his repair was in the $$$$ and my was in the $$$ thx to Ramon's mad skills.

 

[Old Guy]

If some previous installer over torqued the sparkplug and approached or just exceeded the yield point on the aluminum threads, its possible that there could have been gradual plastic deformation of the threads which would release the retaining force on the plug allowing it to back out. Once you get any significant amount of hot combustion product escaping past the threads 'the end is nigh'.

Odd that the reported cases are all for cylinder #5 . If there was going to be a problem with over torqueing or under torqueing, I would have put money on the back 3 rather than on the front.

Tightening by using the deflection angle past gasket contact or by torque wrench are both permissible options. The trick is, NGK (and I think Denso) specify that their torque recommendations are with new gaskets. When I look at used NGK plug gaskets there appears to be deformation in the gasket, so begs the question that if you are one of those people who want to pull the plugs to check things and you are not purchasing new plugs for re installation, do you increase or decrease the torque setting?

Life was so much simpler with old school cast iron!

 

[liftnot]

Back in my hi-school days, pulling plugs on wkend is a standard affair and feeling "proud of it" as I thought I knew something about cars travelling with a toolbox in the trunk just in case.....but got lazy since the birth of the ECU.

Always used new plugs on this car if the old ones are removed(100k miles ago)and I know the person who did the last install but I am not blaming him. it is very strange and I thought I was the 1st special but NO!!:redface: