Just wanted to ask, as I'm very curious about things...

I just recently, pulled pan and lower intake again. I installed new lifters and rolled in new main bearing's. I installed new main bearings and rod bearings last year on the ol' motor, since it was a disaster. When I was doing the main's again I noticed that all were really good accept the thrust bearing, with only wear on the bottom of the shell with some highlights of copper showing. I chalked that up to perhaps my mistake with very little assembly lube. I pulled the rod caps for #'s 4 & 8. As I was looking at them again, I noticed that I have "2" rods with number 5 marked on them. More specific, #5 cylinder and #8 cylinder. I have a diesel knock after the motor decide's to warm up after about 3-5 mins. I isolated it to the #8 cylinder, but cannot for the life of me undestand why it does this. The rod look's good, there was minimal movement of the rod, and the bearing looks great. The sound will go away with about 950+ rpm and whenever you go to drive. The only thing I did was remove some of the carbon ridge @ the top of the cylinder. Could this have been my downfall?

The motor runs good! Great power! I'm lost on idea's.

 

I have never seen that on a ford motor that I've torn down. They were all numbered sequential #1 through #8. I'm betting someone swapped in a number 5 rod from something else somewhere along the line. If you read my build thread, that 5.0 sounded like a diesel knocking once warmed up, the rod bearings were all hammered on the top side. On yours, it could be the piston pin loose also, and the piston rattling around.

 

I have thought about the wrist pin and pondered and pondered. One other thing I want to mention, and it may or may not help any. When I get my scope out and listen, I don't really hear anything from the #8 cylinder...Weird, but when I get on the lower, left-hand side of the tranny bellhousing, just a smidge from the tranny cover plate, I can hear that distinct, "TING, TING.." I asked last year if maybe the flexplate could be cracked, as I had that noise before. I was able to move the tranny back nearly an inch, and I could see areas of red/rust near the center of the plate, but could not see the center.

I checked the TQ bolts and they are all tight. Sometimes it sounds better, sometimes it doesn't. Different weight motor oil really makes no difference in sound. A long-time Ford mechanic of 35 years, he listened and he thinks it's just a wrist pin or pins, not really a cracked flexplate, as it would tend to get quieter with the above method. I guess the easiest solution would be to have a video scope that you could run in between the block and the bellhousing. Unfortunately, I have no concrete floor, just plywood and a gravel driveway, so an inch of movement with the tranny is a feat.

In conclusion, I'm shocked that this sound is there after I complete cleaned the inside of the motor. It get's oil now, WHERE it never did before. It doesn't smoke, and it runs like a BEAST! Hence, I call it the BEAST!

I will look once again at the Rod bearing's I removed last year to see if maybe "1" of them was an odd side, but I'm pretty sure they were all Standard. If anyone has any other method's of checking for a cracked flexplate, I'm game as I love my truck and the new headers really make a difference!