Lost Two Gen 3 LS Engines in my 1986 C10 2WD

[Ricko1966]

Thing is that I watched cylinder #2 intake valve closing very slowly when turning over after the damage had occurred. That's what led me to believe it was valve to piston contact.

The other thing that strikes me as odd is that it ran good when I shut it off. It's the next time I went to start it, it turned over super easy, so either the damage occurred as I shut it off (which doesn't coincide with injectors filling the cylinders while running) or the starter damaged the motor? Just doesn't seem likely to me

See if all the pistons are parking at the same height,check through the spark plug holes.

 

[Ricko1966]

Here's something else to think about. When you tag a valve it's usualy an exhaust valve,because the piston is chasing the exhaust valve shut. The intakes are opening as the piston is moving away from them. I'd takethat engine apart and investigate. At the least I'd see if all the pistons are parking at the same height and pull the rockers on the low cylinders and manually open the valves feeling for binding opening and watching for binding closing., and usually a bent valve will park at a different installed height.

 

[1lejohn]

Are sure neither of these engines are DOD? I'm seeing or imagining I'm seeing a pattern in compression between DOD cylinders.

Thats what I posted earlier.

 

[Ricko1966]

Thats what I posted earlier.

When these things get 10 pages deep,I don't read every post but it is suspicious that the low cylinders are the cylinders that are DOD on DOD engines. It's also suspicious that #2 has had zero,90 or 150 lbs depending on which post you read.

 

[shortboxin]

When these things get 10 pages deep,I don't read every post but it is suspicious that the low cylinders are the cylinders that are DOD on DOD engines.

No one ever answered my question when the DOD question was asked and that was this, "The 2004 4.8 had 706 heads and the 2002 5.3 had 862 heads. Were those used on DOD engines?"

 

[shortboxin]

It's also suspicious that #2 has had zero,90 or 150 lbs depending on which post you read.

You're not aware of the timelines on everything, but when the engine was still impacting (making contact that I presumed to be a valve) I was getting 0 PSI on cylinder #2. When I attempted the second compression test weeks later but on all 8 cylinders, I only got 90PSI on the first attempt. I then gave it a second try once I had checked the remaining cylinders and it suddenly was at 150PSI.

Thing I can tell you for certain is that one valve on cylinder #2 was slow to close when I turned it over with the valve cover off a couple of weeks ago. In other words, it was open when it should've been closed which is where all of the compression was going and why I believe the valves made contact.

 

[Ricko1966]

No one ever answered my question when the DOD question was asked and that was this, "The 2004 4.8 had 706 heads and the 2002 5.3 had 862 heads. Were those used on DOD engines?"

You told us on post 23 it's not a DOD engine. This novel is 5 pages deep,and I'm not going to read every word,or even every post. Even if I did, I do not know everything about every engine chevy ever made by year and displacement. I assumed it was not DOD because you said it wasn't.