I just went through the same deal, but it was the rockers on cyl #1. Before I installed the new rockers, I pushed down on each valve to make sure it was working freely. An exhaust valve on #1 was stuck. With some extra effort, it broke free. However, there was some carbon buildup that broke loose when I did this. I tried to turn the engine by hand and when piston #1 got near the top, it "encountered" this carbon and would not go all the way up. I had to remove the head and clean the carbon out as well as clean up the exhaust valves and seats on that cyl too.
I'm glad to hear you didn't have to pull the head, but just wanted to warn others to check the valve travel and engine rotation before putting it all back together. It only takes a minute and could save a lot of time/damage.
toy_vw wrote:
Well an update for those who are interested.
When I removed the upper valve cover, i found the #4 intake rockers completely failed and off the valves sitting to the side...of 16 rockers 3 were good, 3 failed completely. The others were on their last legs.
This explains why I had no compression on number 4.
I made my own alignment tools and will take a picture of how you can do them from a 20mm m10X1.0 bolt, and a 0.250 roll pin at 2" length.
truck is running much better then ever..idle is awesome, power is back...
Cheers