Help! Knocks bad when warmed up!

[slick35thgt]

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.

 

[trinity_gt]

Probably a rod bearing.

 

[slick35thgt]

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

 

[98COBRA281]

yup sounds like a rod bearing, modulars are big motors (size wise) and need all the oil...

 

[trinity_gt]

Yeah, mods seem very, very sensitive to oil level. At high RPM, I've read that the timing chains transfer a ton of oil to the heads and drainback is slow. If the oil level is already low, it can cause the pan to drain enough to cause oil starvation which can instantly grenade rod bearings.

 

[wmburns]

Get an oil filter cutter tool

Would it be a good idea to rule out a loose spark plug? Perhaps even remove the spark plugs and check their condition.

Was the chatter from the valves or the timing chain? If the timing chain, it is possible the guides (which are plastic) have broken and fallen down into the pan. The large bits of plastic can clog the oil pick-up leading to oil starvation or just plain low oil pressure.

Might be handy to know what the oil pressure really is.

Also, get an oil filter cutter tool. Cut the oil filter open and inspect the media. Look for bits of metal or plastic.

Did you over rev the motor?

Good luck.

 

[stangfanatic]

One of the checks I had to do on my mod was remove the spark plug wires one at a time to determine if it was a bearing or not. If the cylinder does not fire, it removes the pressure on the bearings and it will not knock unless the bearing is completely disentigrated. This is a quick and dirty check, but I agree with all of the above, if you get that low on oil, there is a good chance you spun a bearing.

 

[slick35thgt]

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.

 

[hotmustang331]

Yep these bad boys will spin a bearing in a hurry if the oil is low
Sucks but for some reason they will spin it if it even thinks it's running out of oil.
Another thing I have noticed is that it only seems to really effect 2Vs from what I have seen...don't recall any 4vs spinning bearings due to being a quart or two low

 

[slick35thgt]

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.

 

[smoky]

02 gt

my 02 gt new engine knocks when warmeing up ford say its ok new engine only 150 mile on it

 

[Mr. Rustypwnz]

his knocks after warm up

 

[oxfordgt]

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.

 

[slick35thgt]

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.

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.