Genuine 2005 Chevrolet Trailblazer Cylinder Head

2005 Chevrolet Trailblazer Parts Questions & Experts Answers

• Q: What steps are necessary to replace the head bolts and reinstall the cylinder heads in V8 engine on 2005 Chevrolet Trailblazer?

  A: It will be necessary to purchase a new set of 11 mm head bolts before or during this procedure. Begin by disconnecting the cable from the negative terminal of the battery and draining the cooling system. Remove the intake manifold and the coolant pipe, which is secured by two bolts at the front and two at the rear of the cylinder heads. For 2004 and earlier models, remove the knock sensors from the valley cover, then take off the mounting screws to remove the valley cover and gasket. For 2005 and later models, disconnect the electrical connector from the oil pressure regulator, then remove the mounting screws to take off the valve lifter oil manifold and gasket. Detach both exhaust manifolds from the cylinder heads and remove the valve covers. Next, remove the rocker arms and pushrods, keeping all parts in order for reinstallation. Disconnect the wiring from the back of the alternator, then remove the power steering pump/alternator mounting bracket from the engine, laying it aside without disconnecting the lines from the steering pump. Loosen the head bolts in 1/4-turn increments in the reverse order of the tightening sequence until they can be removed by hand, noting the different lengths and sizes of the bolts for correct installation of the new ones. Lift the heads off the engine carefully, using a pry bar or long screwdriver if resistance is felt, and store the heads on blocks of wood to prevent damage to the gasket sealing surfaces. Ensure the mating surfaces of the cylinder heads and block are perfectly clean when installing the heads, using gasket removal solvents and a gasket scraper to remove all traces of carbon and old gasket material. Check the block and head mating surfaces for nicks and scratches, using emery cloth for slight damage and considering machining for excessive damage. Use a tap to chase the threads in the head bolt holes or spray brake cleaner and use compressed air to remove debris. Position the new gaskets over the dowels in the block, then carefully place the heads on the block without disturbing the gaskets. Coat the threads of the new 8mm head bolts with a medium-strength threadlocking compound before installing them, followed by the new 11mm head bolts, tightening them finger tight and then to the specified torque in the recommended sequence. For 2004 and earlier models, install a new gasket and the valley cover, while for 2005 and later models, install a new gasket and the valve lifter oil manifold. Tighten the bolts to the specified torque, then install the coolant pipe with new gaskets, ensuring proper positioning of the O-ring seal over the coolant pipe nipple. The remaining installation steps are the reverse of removal. Finally, add coolant, change the oil and filter, start the engine, and check for proper operation and any leaks.