Piston hitting spark plug? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

boost addict · 09-20-2013, 04:42 AM

So my motor started missing the other day and after trying to start it back up it make a sound that was like a rod knock. I checked plug number 2 and it was smashed in and crewed. I put a new one in and it did the same thing within seconds. Compression is fine and they are definitely the correct plugs. I feel like its nearly impossible for an sr with stock compression to hit the plug cause the dish in the piston is pretty big and because the done of the head. I feel like it was hit the valves before the plug. Anyone ever had this issue?

Driftwire · 09-20-2013, 06:02 AM

Remove the plug and crank the motor see if you hear the rod knock sound. I think you would have to throw a rod to even be able to hit the spark plug

onehundredoctane · 09-20-2013, 06:20 AM

^solid suggestion.

If that fails to yeild an answer they do make spark plug spacers, thin washers some tuning companies use to position that spark plug facing the direction desired.

shogun! · 09-20-2013, 07:42 AM

Metal flakes in oil? (Failed bearing). Piston pin?
This would make the rod and piston reach higher than normal in the cylinder.

jr_ss · 09-20-2013, 08:03 AM

Pull the plug and look down in there, I wouldn't doubt that you have a piece of metal in that cylinder. The piston should hit the head before it comes in contact with the spark plug. Not to mention the valves...

cotbu · 09-20-2013, 08:29 AM

Quote:

If that fails to yeild an answer they do make spark plug spacers, thin washers some tuning companies use to position that spark plug facing the direction desired.

post the spark plug part number you are using.

Quote:

Metal flakes in oil? (Failed bearing). Piston pin?
This would make the rod and piston reach higher than normal in the cylinder.

Quote:

Remove the plug and crank the motor see if you hear the rod knock sound. I think you would have to throw a rod to even be able to hit the spark plug

These could indicate catastrophic failure.

Let's get the real compression numbers there instead of fine!
Things that don't compress like oil, water and or gas could cause the plugs to get smashed without causing damage to pistons or valve. check those for damage or evidence of said fluids.
Compression itself could also damage the plugs and or valves and cause the piston to knock, this could be from incorrect timing to a thrown rocker arm etc, poor catch can setups.
You have to get in there and check around.
I've seen your previous threads, so no telling what it could really be without, seeing the visual, hearing the audible and or being there physically.
good luck!

conrad_s13.5 · 09-20-2013, 08:47 AM

Something like this happened to a buddy of mine not too long ago.

One of the bolts on the butterfly in the throttle body got sucked into a cylinder and was actually what was smashing the spark plugs.

Pull ur coupler off and see if your missing a bolt

He pulled out the bolt before any major damage was done,..and motor is still running strong

ultimateirving · 09-20-2013, 09:58 AM

Quote:

Originally Posted by conrad_s13.5

Something like this happened to a buddy of mine not too long ago.

One of the bolts on the butterfly in the throttle body got sucked into a cylinder and was actually what was smashing the spark plugs.

Pull ur coupler off and see if your missing a bolt

He pulled out the bolt before any major damage was done,..and motor is still running strong

This is it, The butterfly bolts have snapped and you ingested one. I ruined my first SR this way im pretty sure.

boost addict · 09-20-2013, 01:02 PM

Thanks for the responses guys. Literally just put the motor back in last night after replacing the bearings. I thought the noise was knock at first....haha. Compression was a solid 150. Definitely will check the TB, I've heard of that happening before. I'm about to start pulling the head and ill post up my results

09-20-2013, 04:42 AM	#1
boost addict Zilvia Addict Join Date: Nov 2010 Location: Northwest Indiana Age: 32 Posts: 859 Trader Rating: (12) Feedback Score: 12 reviews	Piston hitting spark plug? So my motor started missing the other day and after trying to start it back up it make a sound that was like a rod knock. I checked plug number 2 and it was smashed in and crewed. I put a new one in and it did the same thing within seconds. Compression is fine and they are definitely the correct plugs. I feel like its nearly impossible for an sr with stock compression to hit the plug cause the dish in the piston is pretty big and because the done of the head. I feel like it was hit the valves before the plug. Anyone ever had this issue?

09-20-2013, 07:42 AM	#4
shogun! Zilvia Junkie Join Date: Mar 2005 Location: Sweden Posts: 367 Trader Rating: (0) Feedback Score: 0 reviews	Metal flakes in oil? (Failed bearing). Piston pin? This would make the rod and piston reach higher than normal in the cylinder. __________________ My +700hp RS13

09-20-2013, 08:03 AM	#5
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,415 Trader Rating: (35) Feedback Score: 35 reviews	Pull the plug and look down in there, I wouldn't doubt that you have a piece of metal in that cylinder. The piston should hit the head before it comes in contact with the spark plug. Not to mention the valves... __________________ My SR20VET Does your VTC gear rattle in your S14/15 SR? PM me.

09-20-2013, 08:47 AM	#7
conrad_s13.5 Zilvia FREAK! Join Date: Jan 2009 Location: STL Age: 37 Posts: 1,533 Trader Rating: (6) Feedback Score: 6 reviews	Something like this happened to a buddy of mine not too long ago. One of the bolts on the butterfly in the throttle body got sucked into a cylinder and was actually what was smashing the spark plugs. Pull ur coupler off and see if your missing a bolt He pulled out the bolt before any major damage was done,..and motor is still running strong __________________ cONtRol FReAkS

09-20-2013, 06:20 AM	#3
onehundredoctane Post Whore! Join Date: Oct 2006 Location: Greensborough, NC Posts: 2,783 Trader Rating: (3) Feedback Score: 3 reviews	^solid suggestion. If that fails to yeild an answer they do make spark plug spacers, thin washers some tuning companies use to position that spark plug facing the direction desired.

09-20-2013, 01:02 PM	#9
boost addict Zilvia Addict Join Date: Nov 2010 Location: Northwest Indiana Age: 32 Posts: 859 Trader Rating: (12) Feedback Score: 12 reviews	Thanks for the responses guys. Literally just put the motor back in last night after replacing the bearings. I thought the noise was knock at first....haha. Compression was a solid 150. Definitely will check the TB, I've heard of that happening before. I'm about to start pulling the head and ill post up my results