my 97 f-150 4.6l v-8 is still knocking.took it to another mech. even he is stumped.engine is good,no leak from exhaust.it almost sounds like the noise is like the teeth on the flywheel is touching something.any suggestions?????

 

The noise coud be a baffle in one of the catalytic converters broken loose. I have an 1988 mercury grand marquis 5.0l v8, started to rattle one day while accellerating up a hill. sounded like the crank was gone, turned out to be the converter, put a small dent with a hammer in it where the baffle was and jammed it tight again. That fix was two years ago and no rattle yet. Another thing to check is if the starter drive gear is fully disengaging

 

If your truck has 100K miles on it or more what you may be hearing is a rattle that is a common problem with the 4.6L. My 97' started it at 109K, my dads 98' started at 105K. The noise I'm talking about sounds worse at cold startup and fades as the engine warms up, but can still be heard if you know what your listening for, especially if you remove the serpentine belt to eliminate fan noise. It sounds a little more solid than a bad lifter rattle, more like a bad wrist pin bearing, and can be heard best from the rear of the engine at the back of the oil pan, or front of the bell housing. I had wondered if it might be the oil pump but I was told on this forum that the pump on these modular engine is at the front of the motor. I still think it could be coming from the trans pump or maybe even the torgue convertor. I was very concerned at first but then I started listening to other trucks in various parking lots and noticed alot of them doing the same thing. My plan is to continue changing the oil regularly, always make sure I let the engine warm up before driving, and enjoy my truck. If something breaks inside the engine, I'll replace it. But, if you do have the same noise and find a good fix for it let us know.