Hey all super random question. I have an 02 4.7 L durango. I replaced spark plugs today and when I was screwing them back in some were inconsistently smooth. Like I could finger tighten most till I got to the washer but 2 or 3 got tight early so I backed out, started again a few times but they just kept doing it so I just had to tighten with my wrench until it felt like it actually hit the head with the washer (they did get progressively tighter) and then I gave it 1/2 turn. Is this a symptom of dirty threads or did I just unknowingly cross thread them? I've crossed threaded things before and they all of a sudden just get super loose and that did not happen so I'm not sure. Any ideas?

Edit: I just thought of this it might be worth mentioning that I was able to hand start them. So all of them were hand started but I only got maybe one or two turns in on the tough ones before I backed out and started over but I did hand-start them all.

by the way I used the NGK plugs I kept seeing reference here and oh my gosh it is so much more smooth and quiet I almost feel like it's stalling out when I come to a stop.

 

Yeah, prolly just dirty threads. A thread chaser while changing the plugs isn't a bad idea.

 

If you're going to use a thread chaser, coat it with heavy grease, so the filings stick to it instead of falling down in the hole. Speaking of grease OP, you might be running across someone who used it or antiseize inconsistently when putting them in. That may explain why some go in easy and some are dry? I always use it personally... the high temp copper stuff and I don't like using a torque wrench with plugs.

 

Anti seize is a must on aluminum heads!