However, it fails because it doesn't have a lot of clamp load from the bolts.
I am not trying to troll this topic but only state the facts.
1. Gm knew there was an issue. In the manuals you will see that the ring gaps in cylinders 7-8 are larger to compensate for the overheating of the rear of the block.
2. Gm tried to fix this issue with their newer improved heads. But that did not help much. The Optimizer and P400 heads are still cracking between the valves. There is not as many reports about them because they have not been available to the general public for very long.
3. My personal testing confirms overheating of the rear of the block on a test stand which is open to air. Now imaging how much hotter it gets once installed against the firewall.
4. Twisted Steel confirmed the poor flow design of the early 6.2 blocks by cutting up different years of 6.2/6.5 blocks and comparing the coolant passages.
5. The failure is from the constant expansion and contraction from the overheating making the gasket soft overtime. Clamp load on the head bolts does play a small part with the issue but is not the main cause. The main cause is from the overheating of the rear of the block.
6. The reviews of everyone that has installed the PBD kit or made their own kit has reported improved lower overall coolant temperatures and balanced temperatures though out the motor.
7. The very early 6.2’s had an extra coolant passage that did not give enough clamping surface area and made for premature failure from the overheating. There was a recall on this where that passage port got capped over.
So in a nutshell… It just makes sense to have the PBD kit or make a similar one. Such a simple upgrade that helps solve so many problems.
Edit: I am not paid by PBD or get any deals or sponsorship from PBD to say these things. I am defending this simple upgrade because I know it works!
