When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
2003 extended cab 2wd 4.0L 5 speed.
Cylinder 3 (pass side closest to cab) blew the plug out. Lucky me. Ill try to post a pic of the plug threads i think it has to have helicoil. Some people say chase it first that the plug metal is softer than the head metal.. true or false? I dont wanna do this twice if its not a good idea just to chase it. Also can you do any of that with the head still installed or is it mandatory head removal.
The threads look a little rough but they're still there. I'd try chasing it. Put grease on the chaser (tap) to catch any pieces.
It looks like every plug in the world needs to be cracked free then be doused with a lube and/or carb cleaner to break down carbon followed by "back & forthing".
Slow removal of plugs appears to be the new norm.
4.0l Sohc head is aluminium. The spark plug threads are cut into aluminium. Definitely softer than a spark plug's steel threads. If you blew the plug out and it wasn't loose there's not enough thread left to use, you'll need to either retap or repair, or get a new head. I'd get a junkyard head over trying to mess with a helicoil.
I tried to get a drill bit in there and couldn't. My cassettes for timing chain in the back was broken anyways and has to be re done so I pulled the motor. The spark plug will go all the way in without threading at all so it will definitely have to be re tapped. Not sure the route I'll take as moneys kind of tight and I just spent 800$ on all the timing and clutch stuff for the rest of the engine.
"The spark plug will go all the way in without threading at all so it will definitely have to be re tapped." You can't retap what isn't there.
Besides a helicoil or other threaded insert, maybe there's room to go to a larger spark plug?
The 14mm hole might be expandable to accept an 18mm plug. Anybody ever heard of this?
If doable you'd have to match the performance of the specced plugs.
It sounds like your best option is get another head off a junked engine and swap your valvetrain in. Just use the camshaft bearing caps and camshaft off the new head. Don't swap your camshaft into the new head as they will have worn in differently.
08-27-2021
