#7 cylinder swallowed a valve last night - '98 Mark VIII - swap, rebuild or junk?

[WadeLovell]

Our clean and previously well behaved 1998 Lincoln Mark VIII with 190,000 threw a P0307 code. As soon as my wife saw the CEL, she pulled over and had it towed home - she's pretty great that way.
I popped the spark plug cover off and immediately noticed the #7 COP rubber boot had been shredded which was followed by a deep sinking sensation in the pit of my stomach.
Looks like an exhaust valve broke off and shoved the spark plug out, while the valve was being pulverized between the piston and the cylinder head. The question now is, "What next?"
Please pick your favorite option(s) and explain your reasoning.
1) Clean out the debris and drive on 7 cylinders until...
2) Pull the head and clean out the debris before deciding what to do.
3) Swap out the engine
4) Rebuild this engine (right and completely)
5) Call it quits on this Mark VIII

 

[chris2523]

confirm valve failure.
its possible it was just a blown spark plug. this happens.
in which case, heli coil or time sert the head and keep driving.

if in fact bad bad things have happened, your basic options are,
1, if its nice and you like the car, put a motor in it.
2, if its not nice and you're not as big a fan, part or sell whole to someone who will part it.

its not really worth it to pull apart and fix a stock motor.

good luck.

 

[driller]

Not likely a valve. You could easily pull the valve cover to inspect though the drivers side (#7) is a PITA.

 

[Rockbottom]

Our clean and previously well behaved 1998 Lincoln Mark VIII with 190,000 threw a P0307 code. As soon as my wife saw the CEL, she pulled over and had it towed home - she's pretty great that way.
I popped the spark plug cover off and immediately noticed the #7 COP rubber boot had been shredded which was followed by a deep sinking sensation in the pit of my stomach.
Looks like an exhaust valve broke off and shoved the spark plug out, while the valve was being pulverized between the piston and the cylinder head. The question now is, "What next?"
Please pick your favorite option(s) and explain your reasoning.
1) Clean out the debris and drive on 7 cylinders until...
2) Pull the head and clean out the debris before deciding what to do.
3) Swap out the engine
4) Rebuild this engine (right and completely)
5) Call it quits on this Mark VIII

Our clean and previously well behaved 1998 Lincoln Mark VIII with 190,000 threw a P0307 code. As soon as my wife saw the CEL, she pulled over and had it towed home - she's pretty great that way.
I popped the spark plug cover off and immediately noticed the #7 COP rubber boot had been shredded which was followed by a deep sinking sensation in the pit of my stomach.
Looks like an exhaust valve broke off and shoved the spark plug out, while the valve was being pulverized between the piston and the cylinder head. The question now is, "What next?"
Please pick your favorite option(s) and explain your reasoning.
1) Clean out the debris and drive on 7 cylinders until...
2) Pull the head and clean out the debris before deciding what to do.
3) Swap out the engine
4) Rebuild this engine (right and completely)
5) Call it quits on this Mark VIII

Our clean and previously well behaved 1998 Lincoln Mark VIII with 190,000 threw a P0307 code. As soon as my wife saw the CEL, she pulled over and had it towed home - she's pretty great that way.
I popped the spark plug cover off and immediately noticed the #7 COP rubber boot had been shredded which was followed by a deep sinking sensation in the pit of my stomach.
Looks like an exhaust valve broke off and shoved the spark plug out, while the valve was being pulverized between the piston and the cylinder head. The question now is, "What next?"
Please pick your favorite option(s) and explain your reasoning.
1) Clean out the debris and drive on 7 cylinders until...
2) Pull the head and clean out the debris before deciding what to do.
3) Swap out the engine
4) Rebuild this engine (right and completely)
5) Call it quits on this Mark VIII

 

[Rockbottom]

Valves and valve stems are very strong. Take off the valve cover carefully moving parts that are in the way. Get your camera out and take a lot of pictures before you remove the cover. One can't become confused when you have some pictures to go by. Once the cover is off you can see if theres a valve missing in the head. Another way wouild be to get all the remaining spark debre outof the hole. Its deep so a magnet will help. Get a compression gauge on it if possibel or put something over the spark plug hole and briefly crank the motor so as not to damage it if there is meteal inside the cylinder. You wil know now if it swallowed a valve or its not a valve. Don't pull head untill you try this.You should feel the compression or see it on a gauge if the valve is in place. If its bent you can tell that too by inspection. Turn over bu yhand first as to not damage the 4.6. It would take a luckey hit and a lot of piston preasure to push a threaded spark plug out of a threaded hole.

 

[Rockbottom]

Valves and valve stems are very strong. Take off the valve cover carefully moving parts that are in the way. Get your camera out and take a lot of pictures before you remove the cover. One can't become confused when you have some pictures to go by. Once the cover is off you can see if theres a valve missing in the head. Another way wouild be to get all the remaining spark debre outof the hole. Its deep so a magnet will help. Get a compression gauge on it if possibel or put something over the spark plug hole and briefly crank the motor so as not to damage it if there is meteal inside the cylinder. You wil know now if it swallowed a valve or its not a valve. Don't pull head untill you try this.You should feel the compression or see it on a gauge if the valve is in place. If its bent you can tell that too by inspection. Turn over bu yhand first as to not damage the 4.6. It would take a luckey hit and a lot of piston preasure to push a threaded spark plug out of a threaded hole.

 

[93mark8rules]

My dad had a BMW that gave me a hard time getting the old spark plugs out. I didnt know that on an aluminum head tightening and loosening the spark plug over and over to get it out can damage the threads. So a week later he had a spark plug fly right out of it. I ran a spark plug tap through the hole and put a new spark plug in and we never had trouble again... It may not necessarily be a dropped valve... Also it usually sounds like a bad rod knock, Ive had it happen on a 302 with a mismatched valve train. I agree with the others take the valve cover off and check everything first..