First off, I hope this is in the right place, if not please move it to the right section.

Long story short is that I rebuilt an 05 gen 4 6.0. I used the same rods and pistons, but put new cam, main, and rod bearings in with new rings. I had an issues with voltage which caused a fueling problem and it to go lean.

We did a compression test and every cylinder except #7 read 175psi and #7 was 0psi. So we pulled the heads, pulled the motor mounts out to lift the engine, and pulled the oil pan. The original plan was to just swap #7 rod/piston out and throw it back together since no others showed signs of detonation.

When we pulled the caps off #7 we saw that the rod bearings were trashed. So we decided to pull #8 also, but only to find that it was a little worse than #7. So my question is by looking at this pic, could detonation be the culprit here or does it look like it was metal on metal to you? The motor only had almost 500 miles on it and two oil changes. One at 150 miles and the second at a little over 300 and the oil looked good with no signs of abnormal wear for new bearings. Here's the pic of the piston and the #7 & #8 rod bearing.



#7 on top #8 bottom. The copper worn bearing was the rod side, the other is the cap side.
Unfortunately I had to drive the car home 9 miles because I was leaving my car in that area, and the tow bill going from one state to the other across the river was crazy. Plus the damage was done. But on cold start the oil pressure was over 60psi, hot driving was a little over 50psi, and hot idle when I got home was over 40psi. That's how it was every since the first start. The crank was turned 10/10 and the bearings are king racing XP series for the size of the turned crank.

Any thoughts to if it's something other than detonation on the bearings would be appreciated. I just don't want to assume that's all it was, then pull the motor to put new bearings in and have it happen again.

Thanks,

Dave

 

How do the bearings look on the other pistons? If it is just those two cylinders' bearings and you still had good oil pressure, I would think you have an obstruction in the oiling path going to those bearing.

 

Detonation will squeeze bearing material out the sides of the upper half.
If there is metal to metal contact on the upper shell it will smear and carry damage down to the lower half.

 

I haven't checked all of them yet because the motor is still in my car. But we pulled #7 completely out, checked #8 & #3 and they all looked the same. We also pulled #4 main cap last night to look at the main bearing on it and it's not completely trashed, but it needs replaced so the motor is coming out. Wouldn't the oil pressure to be low if there was a blockage since the sender is at the top? I was thinking that it wouldn't register it?
That sounds like what happened then most likely.

I'm going to go ahead and swap to a melling pump even though my oil pressure was still good and check all the clearances again before I put it together. I guess the whole cause for the damage was detonation then. I just wanted to get opinions on it because I didn't want to think that it was fixed, only to run into problems again.

I guess the only decent info I can add to it is, that anyone who has a bmr tubular k-member on a 4th gen fbody, can change rods/pistons without pulling the motor without even lowering the k-member. Just pulled the head, took the motor mounts out, jacked the motor up, and pulled the pan right out. It was definitely easier not having to lower the k-member. Only mentioned it because maybe it can save someone some time and extra work if they didn't already know.

If anyone has anymore input, I'll gladly take it.

 

If you are taking apart a good running engine for a rebuild (just for example) you typically have one set of procedures for cleaning/re-assembly.

If you are taking apart a motor with spun bearings, metal/trash and debris has been floating around, I will highly recommend you pay extra special attention to the cleanliness, be sure to get inside as far as possible to every oiling orifice with a good cleaning utility, if any of that metal trash is left behind it will undoubtedly score/block and re-snowball the next rebuild into oil related failure.

I say this because, you probably intent to send it to a machine shop for the cleaning? And if so, they will do the same thing to it whether its been thrashed inside or not. In other words, they don't know its had that kind of damage, they just do the same routine regardless. And it might not be good enough for what you have there, so either mention it and make a big deal about it or clean it up yourself somehow.

 

Thanks for the heads up.

I had actually just rebuilt it . It was an 05 6.0 with 2 spun rods bearings and went through it thoroughly and cleaned everything. I used purple power degreaser which actually melted everything off to the bare metal, a hot power washer, air compressor to dry and blow any debris left behind, and then our buddy has a hot tank to make sure everything was cleaned if missed. I didn't want to risk it by cleaning that pan, so I used the one off my ls1 with 21k miles on it. It looked brand new inside but I still cleaned it really good too.

I'm hoping to not do this again for a while, it's a pain with this turbo ac kit because the ac stuff is always in the way of everything you're trying to get to