QUESTION: I have a 98 pathfinder, I can feel the piston slapping against the number two spark plug you can also hear it, at first I thought it was a lifter Any ideas?
ANSWER: Hi Rich -
If you just replaced your spark plugs, you might want to ensure it is the correct application for your vehicle. Perhaps the reach is too long.
However if it is just one cylinder, then you might have some deeper issues. Is the car performance OK as far as medium to high speeds? How have you determined it is the number 2 cylinder?
Have you taken a compression test?
I am also thinking could be the con rod bearing for that cylinder, but that would be unusual.
Hope this helps -
---------- FOLLOW-UP ----------
QUESTION: I was able to determine it was cylinder #2 because I put my finger on the spark plug boot and you can feel it. The spark plugs have been in for three years. Car performance is fine at all speeds and at idle
Hi Rich -
Next step is to remove the #2 spark plug and manually turn the engine until the piston reaches TDC for that cylinder. Check for damage through the spark plug hole, whether the plug is hitting the piston with the electrode, should have a mark at the top of the piston. Also check the piston for build up. Excess could be hitting the valves. Either way, the marks you are looking for on the head of the piston will tell you what is going on.
Also while you have the plug out, take a compression test of that cylinder as well.\
at this point you are looking for a bad con rod bearing or bad rings.
hope this helps -