Chevrolet Trailblazer Valve Job Part 1; Teardown

Part 2 here:    • Chevrolet Trailblazer Valve Job Part 2; Re...   The 4.2 I6 in This 2005 Chevrolet Trailblazer has a rough idle,cylinder 3 misfire, and occasional stalling due to low compression. Compression and leaktown tests revealed a leaking exhaust valve. After a year or two I finally have a chance to tear into it and find the problem. No one else has made a video on how to get the cylinder head out, so I did. Valve problems are common and costly to fix on this engine, and There is a TSB for valve wear for 2002-2007 models. This engine is DOHC and the front cover and oil pan must be removed to retime it. The front axle goes through the oil pan which makes removal a huge undertaking. To avoid this The timing chain must be held in place during the entire operation. To have this done by a dealership will run you $3,000-$4,000. The 4.2 I6 was used in the GMT 360 Platform which contained the 02-09 Chevrolet Trailblazer, 02-09 Gmc Envoy, 02-04 Oldsmobile Bravada, 03-07 Isuzu Ascender, 04-07 Buick Rainier and 05-09 Saab 9-7X. A 5 cylinder version was used in Chevrolet Colorado, GMC Canyon, and Hummer H3 Trucks and suffers similar valve issues.