Head gasket replacement checklist

[Matahoe]

positive crankcase ventilation. The gases along with oil from the crankcase, gets sucked into the TB and via vacuum and ends up in the intake and runners. definitely get a catch can if you dont have one

I've seen catch cans but I would rather not have another thing to service.

Dug a bit deeper this afternoon and realized that GM made a newer design valve cover for the 2007-2011 5.3/6.0. Part 12570427 but it is meant for AFM/DOD. I wonder if it would work similar on my LM7? Worth a shot maybe to solve the oil in the intake issue.

Aside from that both exhaust manifold heat shields are rotted. Oh yeah draining the coolant required removing lower radiator hose. That was messy to say the least.

 

[Matahoe]

Ahead of schedule, shoulda planned on throwing a cam in it

I actually thought about doing this. It would increase peak HP by about 50 or so from what ive seen. It would however more than likely hurt the low rpm torque. I don't know. I'll take a look at the numbers from a few manufacturers. Maybe try edelbrock, crower and compcams.

 

[Justinj360]

positive crankcase ventilation. The gases along with oil from the crankcase, gets sucked into the TB and via vacuum and ends up in the intake and runners. definitely get a catch can if you dont have one

You're not saying that's normal, are you? I'm planning on changing my intake manifold gasket soon and I don't want to find that under there.

 

[about20ninj45]

You're not saying that's normal, are you? I'm planning on changing my intake manifold gasket soon and I don't want to find that under there.

Yes. It's normal because it's ducked into the intake and runners

 

[Matahoe]

One head removed. It took me a bit longer as I wanted to try and keep the exhaust manifold connected. Didn't work as I planned as the head bolts are covered. I'll probably just replace both ex.manifolds anyway as they come with heat shields.

As you probably have guessed I took my time today. Wasn't in as much of a rush as I thought. It was 95F in my garage at noon. So I had to have a few beers slipped in there. Around 3pm I decided to use a fan. It was around then that the head came out.

Tomorrow I will be contacting my engine shop. Will see what the estimate turns out to be. The valves, piston tops and chambers look good at first glance. Havent looked at the piston sleeves yet. The shop said cleaning and pressure testing is numero uno. I did see one tiny swiped clean area next to a head bolt (see pic). Lets hope its not a crack. Any ideas on how much the clean and test runs about?

 

[Matahoe]

...cont.

 

[Matahoe]

The valves were removed from head today. All intake valves seemed very clean. All exhaust valves were somewhat pitted and definitely contributed to lower than normal compression. I will be lapping all the valves after the head gets back from being cleaned and checked. Note that the spatter on the last picture exhaust valve is from when I arc welded a bead onto a broken exhaust bolt that was broken off in the head. A benefit of replacing head gaskets is that you can fix the broken exhaust bolts.

View attachment 203363

 

[Matahoe]

All mating surfaces are true and no warping or erosion noted. I'm almost tempted to skip the machine shop checking them and just clean, lap/reinstall valves and go. A brass brush and Berryman B-12 Chemtool works great at removing stubborn head gasket material. Last picture is my preliminary head / combustion chamber scrubbing. Will use some Purple Power and my pressure washer tomorrow. I've also had good luck with the purple Members Mark degreaser available at Sam's club. I think its made by Ecolab. It says it attacks carbon and works very well on engine parts.

 

[swathdiver]

Dug a bit deeper this afternoon and realized that GM made a newer design valve cover for the 2007-2011 5.3/6.0. Part 12570427

Compare yours with that part number and this number: 12642655. This is the updated one that was put on mine. The difference may be in the diameter of the fitting, not sure.

It would increase peak HP by about 50 or so from what ive seen. It would however more than likely hurt the low rpm torque. I don't know.

Only Crane Cams and Cam Motion offer camshafts made for trucks where no bottom end horsepower and torque is lost. Crane calls their three "Powermax" and Cam Motion calls theirs "Drop-In". Upgraded valve springs are not required.

https://www.hotrod.com/articles/ls-cam-test-comparison/

http://markenperformance.com/n-8673...-for-ls-stock-oe-valve-trains-4-8l-to-6l.html

http://www.cammotion.com/camshafts/5-3-stage-1-ls-truck-camshaft-200-204-114-3/

https://www.performancetrucks.net/f...tage-2-drop-cam-testing-results-depth-531293/

https://ls1tech.com/forums/dynamome...otion-5-3-drop-cam-results-41rwhp-22rwtq.html

 

[Matahoe]

Compare yours with that part number and this number: 12642655. This is the updated one that was put on mine. The difference may be in the diameter of the fitting, not sure.

It appears that 12642655 is for 2009 and above. A search on different GM parts dealer websites shows 12570427 for 2003-2008.

https://www.trailblazerssforum.com/forum/viewtopic.php?t=187