This thread was saved without dates. "Around Sep 2004" is estimated from neighbouring threads.
Does anyboyd experianced broken spark plugs?
Yesterday I decided to check spark plugs as the engine was working very strange. I found the 1st and 3rd spark plug broken at the pin side. I replaced all 4 and everything is ok now. What do you think made spark plugs to brake?
are you running more boost or low octane gas?
Have you taken the car over some nasty bumps...plugs really don't like to get knocked around..
I've broken a few over the years when taking them out....when the socket isn't fully seated over the sparkplug, and it puts pressure on the ceramic, and snaps it.
I found that the old set of plugs had more than 10k run on another car, and istalled by my mechanic when he was trying to solve a problem with misfiring 2 months ago.
Nicholas I've had exactly the same problem with two CA18DET's. I had a total of 3 plugs crack in the ceramic section, outside the head (not inside due to e.g. detonation). It looked like damage caused by a lateral sheering force. This was with the factory ignition system (coilpacks mounted directly on top of coils). I now have a custom ignition system (igniters and coils mounted on the engine bay wall, with leads to the plugs), and it hasn't happened since. I suspect it was due to the engine twisting the coils against the coilpacks, but I couldn't prove it.
Nicholas I've had exactly the same problem with two CA18DET's. I had a total of 3 plugs crack in the ceramic section, outside the head (not inside due to e.g. detonation). It looked like damage caused by a lateral sheering force. This was with the factory ignition system (coilpacks mounted directly on top of coils). I now have a custom ignition system (igniters and coils mounted on the engine bay wall, with leads to the plugs), and it hasn't happened since. I suspect it was due to the engine twisting the coils against the coilpacks, but I couldn't prove it.
I doubt the coil packs would cause cracking......my Maxima has coil packs on it's VQ30DE, and I've never had a cracked plug on it in it's so far 137,000 mile life.......my guess the cracked ceramic is from stress when taking out the plugs......especially on the S12, since some of the ones on the intake side are pain in the arse to get to, and is hard to get a socket in there to them and seated squarley on the plug.
What was broken is the ceramic section on pin side inside the cylinder head.
I doubt the coil packs would cause cracking......my Maxima has coil packs on it's VQ30DE, and I've never had a cracked plug on it in it's so far 137,000 mile life.......my guess the cracked ceramic is from stress when taking out the plugs......especially on the S12, since some of the ones on the intake side are pain in the arse to get to, and is hard to get a socket in there to them and seated squarley on the plug.
No, plugs were not removed. They cracked in the car and for no apparent reason. If you can think of a reason why they would have exhibited lateral sheer breakage I'm all ears. CA18DET btw, so there is no intake side as such for the plugs.
What was broken is the ceramic section on pin side inside the cylinder head.
Thats almost certainly detonation. Buy decent fuel, turn down your boost, and check your tune.
Ohh, don't know then.....maybe it was the opposite. Maybe they were over torqued when they were put in, causing a hair line crack and vibration finished them off over time....who knows
No, plugs were not removed. They cracked in the car and for no apparent reason. If you can think of a reason why they would have exhibited lateral sheer breakage I'm all ears. CA18DET btw, so there is no intake side as such for the plugs.
Thats almost certainly detonation. Buy decent fuel, turn down your boost, and check your tune.
Regarding fuel, since May here in Cyprus we have stoped useing Leaded Super grade, and we can now choose between Unleade 95 and unleade 98.
Plugs can be cracked from OVERTIGHTENING them... I normally torque plugs to 12-15ft/lbs. Any more and they can crack under use from the threads being too tight. I've also had plugs crack when attempting to remove them because they were torqued too tight. They're not supposed to be SUPER tight, just snug.