Help! Knocks bad when warmed up!

Ok, I'll start off the story by saying that I have a '99 GT, and it is well maintained and babied, no oil leaks, nothing. Never had any engine problems ever.

Last night for the first time this year, I run the car against several buddies of mine just for fun. I probably made 6 eighth mile runs overall, then I headed on my way home and heard a bit of a chatter at low RPM, so i stopped at the nearest gas station, and checked the oil and it was over a quart and a half low!! The car is only 2500 miles in on the current oil change, and I don't even drive it much as it is not my daily driver. It doesnt leak ANYTHING, i could eat off the oil pan. Ive never seen the car smoke, unless it puffs something undetectable at WOT, and over time it has added up.

Anyway, I added oil and limped it home, never getting over 2k rpms. I started it up this morning and it was completely silent, never made a noise. Revved it and it revved free just as it always has. Once it warmed up... knocked again, very noticeable, even from a distance.

Performance-wise, the car doesnt seem to have lost power, but i havent took it up in the RPM's because, quite frankly it doesnt sound safe.

So what do you guys diagnose this to be. Can it be saved? If it ends up being junked, I've got a 5.4 swap plan ready to go into effect, but if something simple can get my 4.6 going again, I will keep it in, as it is a great running car.

THANKS. I appreciate any help or advice.

That's kind of what I was thinking... ugh.

Yup, I'm pretty sure that's what I'm looking at. Changed the oil today to rule it out, and it didnt help. Seems to be getting progressively worse.

But that's ok I guess. As bad as I hate it, the car isn't my daily driver, so it'll give me all the more reason to put my 5.4 swap plans into action. I've been reading into it for a long time to just have a torquey, reliable street car, but with my stock 4.6 already running 9.0's in the eighth, it just wasnt a necessary swap at the time. Now I've got some motivation.

Indeed. After further research, I believe Im going to go the more traveled route and just pull it apart and freshen everything up, throw in a few go-fast goodies while im at it.

I'm definately going to check my oil levels more often now. I just drive it so little, and I wasnt far into the change that I had assumed it would be ok. In its defense, I was extremely hard on it the night it began to knock. doh.

oxfordgt said:

A 2v 5.4 is a waste of time, effort and money. If it is a rod bearing then spend the $100 on new bearings and change them out.

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A little more research ended up with me discovering this. I'm just going to pull apart the 4.6, throw a crank kit, windage tray, and new oil pump in it, call it a day. I'll make sure to pick up some LT's before I throw it bolt it back up in the car as well, save me a lot of time on the install.