Spark plug porcelain broke off discussion in gen 2 prius care maintenance and troubleshooting started by thomas ziongas feb 10 2014.
Ceramic part of spark plug broke off.
I was changing the spark plugs and when i got to number 7 the top of the spark plug sheered off when i tried to take it out leaving only the threads and about 3 8 of an inch of the base sticking up still threaded in the head.
The piece that broke off would have to be very small and land perfectly for it to be wedged in this small gap.
It is ceramic and will certainly damage the piston and head if you run the engine with it in there.
Let s say you are working on a simple tune up and during spark plug removal one breaks off below the hex leaving the threaded shell stuck fast in the head.
Initially encountered misfires on cyl 4 on wot however car ran fine if i didn t go into boost.
Well it turns out that a ceramic piece broke off of the spark plug and fell into the first cylinder.
I own a 2004 volvo xc90 t6 2 9l awd with 6 cyl.
It may never happen to you but if it does don t panic.
That can happen with any spark plug but most frequently with the smaller 5 8 hex size.
Action refer to the following service procedure for techniques to remove the spark plugs and extract broken spark plugs.
Twin turbo with catalytic converter while changing the spark plugs one broke off all the ceramic below the threads and possibly the metal finger of the plug i m not sure and fell through the valve after bending it and causing the valve to burn possibly.
I had a similar problem when servicing my dads sthil saw but managed to gently crank the piston around to grab the broken part of the plug.
From my earlier post i managed to get the compression test adapter out of the spark plug hole.
The tip of the spark plug fell into the engine.
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I rotated the cylinder to begin the compression stroke on the first cylinder but i still feel stuck on what to do.
If you want you could have a mechanic do a compression check on each cylinder.
I drained my oil but it didn t come out and i am trying to avoid taking the head apart.
This may cause damage to the spark plug and leave part of the spark plug in the cylinder head.
Then we took the small tube off and put the spark plug wires back in cyl 1 3 4 and tried that.
The normal piston to cylinder wall clearance is from 003 to 008 of an inch it can be less or more depending on engine components intended use etc.
Top of spark plug broke off.
Affected engine build dates are as follows.
Cast iron head and block.
Checked all wiring coils and plugs on cycl4 and low and behold about half of the ceramic sheath was.