Driving home tonight, a few blocks from my house I step on the gas & a loud surprising noise startles me. Hmm, sounds like an exhaust leak? I drive home slowly, pull in my driveway to have a quick look in the dark. I start on the drivers side (it sounded like more on left side), underneath, I don't see anything obvious wrong with the exhaust, under the hood looks normal too.

Start it up to listen for the leak, at idle it's very loud, like straight out of the headers, underneath it doesn't really sound like it's there. I listen under the hood & it seems like it's more in there, but not really from the headers, sounds more like it's in the middle of the motor & towards the back. I still don't see anything, but I think I'm smelling gas fumes. Now, it gets a little strange, when I rev the engine, the sound pretty much goes away . Now the engine seems to be running a little rough. No CEL though.

I'm kind of stumped. I'm thinking maybe something to do with EGR? It looks like there may be EGR on this motor, I see a vacuum diaphragm looking thing sitting right on top of the intake. I need to figure out the problem & get it fixed in time for the 23rd

Ok, the good news is that through further inspection I found the source of the problem, spark plug came out of head

Coil is thrashed too. I tried to put another spark plug in that hole & it won't thread at all

Stay tuned for further updates

Ok, so my friend lent me his nice little Snap On plug thread chaser tool, only one problem the opening in the head isn't big enough for the socket required for this tool . Taking the valve cover off won't help matters much, it's still the same ID down the head itself.

After doing some research I found a tool called a BackTap that looks like it might work. I'm going to see about buying one of them. My research also led me to find out that this is a fairly common problem in many Ford engines with AL heads. I also found a guy that claims to be able to make permanent insert repairs that are guaranteed, at a price. I may end up having him do the work, but I'm looking for other options still.

Ordered a Back Tap just now, should have it on Thurs.

Yes, this was fairly common amongst the early ford 4.6 & 5.4 AL heads... "Side Note" Although the early aluminum block made by Teksid were in fact stronger then most later blocks...

Well, I didn't even try to use the Back Tap, it looked like it was way too short, it's a long way from the threads to above the valve covers. I had the car towed to a local engine rebuilder & they put a Timesert in. So, everything seems fine for now. Funny thing was that there was still a CEL after it was fixed & running good, oh well, I hooked up my Predator Diablo to see what trouble codes there were, but it said none, I hit the Clear codes button anyways, & it seems to have done the trick, no more CEL .