Genuine 1999 Pontiac Grand Prix Cylinder Head

1999 Pontiac Grand Prix Cylinder Head Parts Questions & Experts Answers

• Q:

  What precautions should be taken before loosening the cylinder head bolts and what steps are involved in removing and installing the cylinder head in 3.4L V6 engine on 1999 Pontiac Grand Prix?

  Posted by Melquicedec D.

  A:

  Permit the engine to cool for some time before attempting to loosen the cylinder head bolts. In engines with high indication number or during the overhaul the camshaft lobe height should be checked before removing the cylinder heads. First of all, there is a necessity to unbolt the cam carrier together with the intake manifold to remove the cylinder head. If the front cylinder head has been unbolted, then it is necessary to loosen the oil dipstick tube mounting bolt and the electrical connector to the temperature sender; for the rear cylinder head, it will be sensible to unlock the electrical connector for the oxygen sensor. For the front cylinder head, remove also the exhaust manifold, while for the rear remove the exhaust crossover pipe, disconnect the exhaust pipe at the exhaust manifold, and for manual transmission cars the rear air hose from the air pipe. If the rear cylinder head is to be removed, the timing belt tensioner bracket should be unbolted. Slowly raise the head off the block being very careful as not to pry in between the head and block Finish this by checking for any loose head bolts; then with a hammer and wooden block to tap around the head surface to break the gasket surface while mind the location of dowels in block. After removal of the unit, the head should be placed on wooden blocks to avoid any harm on the gasket surfaces. For installation, it is paramount that the sur faces on each cylinder head and block are free from any contaminants. Oil on the mating surfaces absolutely must not be permitted because it will cause the gasket to leak; to remove carbon and other gasket deposits from the heads use a gasket scraper and then wipe the remaining surfaces down with some lacquer thinner or acetone. Spread shop rags over any of the holes in the block in order to prevent debris from blowing in and for any debris that falls into the cylinders, use a shop rag or the vacuum cleaner. Check the block and head mating surfaces for digs or holes that may rank; these can be flied off if slight but may require machining if there are profound holes. To remove dirt, corrosion, sealant, and damaged threads from the head bolt holes use a tap of the right size. Just put it on the dowel pins of the block in such a way that the metal tabs between the cylinders are up, and set the head gently on it such that it does not dislocate the gasket. Screw in the Pre-Load bolts and tighten them in accordance to the torque indicated and then rotate the Pre-Load bolts in the following sequence. The subsequent installation steps are done in the reverse order to the removal process and thereafter replace the engine oil and filter.

  Answered by GM Parts Specialist Henry / Feb 02, 2026