Time for a new engine? or another way..

I Have a bad cylinder due to a broken spark plug. It now has low compression in that one cylinder and the engine it running poor. What to do now? is my only option to replace the engine? or is there another way.

ColoradoHills said:

I Have a bad cylinder due to a broken spark plug. It now has low compression in that one cylinder and the engine it running poor. What to do now? is my only option to replace the engine? or is there another way.

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Let's start with the basics: year, engine, transmission, transfer case.

You say that the spark plug broke. What specifically does this mean? Ditto what you mean by a bad cylinder.

Low compression could be a number of things, so let's start with the above and go from there - that'll determine how best to go about fixing the problem.

1998 4.0 inline 6 np231
the plug broke off (shattered) inside cylinder three. I now have about 35 psi in that one cylinder.

Is there an chance of repairing the cylinder walls and piston?

ColoradoHills said:

1998 4.0 inline 6 np231
the plug broke off (shattered) inside cylinder three. I now have about 35 psi in that one cylinder.

Is there an chance of repairing the cylinder walls and piston?

Click to expand...

You really have to pull the head or use a boroscope to inspect the cylinder wall and the valve seats. Depending on how deep any scoring is, you might be able to hone out light damage or bore/oversize for moderate damage. Honestly at 35psi compression though, the prognosis isn't that great.

Pull the head.
Could be a piece of the plug just got hung up in a valve and now it's not seating.
Look at the bore with the head off. If it's OK, get a valve job on the head and put it back together and run it.