Valve Seals?

[efi4eye]

My original engine is about to hit 170k and it developed a miss. I replaced the original(!) plugs and it started running well, only to start missing again within a few days. The coils all seemed good, I removed the plugs to check them and found some heavy deposits on the #8 spark plug electrode. I cleaned it off and the engine ran fine again, until a day or two later when it started missing again. I have noticed the engine puffs blue smoke every once in awhile on startup, but never while it’s running.

To me, it seems like it needs valve seals. Could that much oil be collecting on the spark plug from the bad seal or am I overthinking it? It seems like the only solution would be replacing the valve seals which I’d like to do without pulling the engine.

I’m looking for opinions, is there something I’m missing? I pulled the #8 plug last night and sure enough, electrode is caked again

[Fordtech7]

The valve stem seal could be the cause but if the guide has excessive wear than the new seals won’t do their job. Just food for thought.

[RubberCtyRauder]

#8 has poor cooling flow in the head causing it to run hotter, could be start of valve issue. There is a head cooling mod, but it won't fix issues if already damaged.

[efi4eye]

Good point on the valve guides... honestly the startup smoke once a week wouldn't bother me if it didn't keep oiling the #8 plug

[FordNut]

Take it to the dealer, have them run a diagnostic to find out which cylinder is missing for sure, then change that coil. The Marauder won't turn on the CEL until the miss is a constant dead miss, so you can't run a diagnostic with a SCT code reader.