The block isn't necessarily the problem with the car. The design is poor, the connection between the upper plenum and block don't cool at the same rate, and can cause cracking/cooling issues. I haven't had either of these cars for such a long time. I have my 2004 silverado that has been nothing but a treat to drive and maintain.being a employee of gm for 15 years I have to tell you that your wrong. the block used for the 3.4 is the same as the 2.8, 3.1, and 3.3. the stroke is the same and the bore is different
Trust me, I'm one the biggest Chevy fans around, but I will curse the 3.4L DOHC engine until my death.
This is such an old thread....
But let me refresh. The issues I had to work on with those 2 cars were by far the hardest/worst. Its a fairly common car, with a fairly poor engine layout. The rear spark plugs all sucked to remove, the PROM chip I did upgrade but never resolved the idling issues. I even checked the spark of each plug from the coil pack with the reisitor tester. I still remember doing all of this work. I traced wires, clamped onto other to verify they were working. I had a cam shaft sensor go, the transmission in both cars blew up (i don't drive my vehicles hard, i promise. if you don't believe me, you obviously dont' know how well i take care of my truck.) Anyway I will attest to this being probably one of the worst engines that GM has ever put out. I'm glad to see it didn't continue in that manner.