Mercury 4R3Z-6049-AA Cylinder Head Assembly

The engine must be completely cool when the heads are removed. Failure to allow the engine to cool off could result in head warpage.

Caution 1: These engines are difficult to work on and require special tools for many procedures. For any procedure involving timing chains, camshafts, or cylinder head removal, the steps must be read carefully, and disassembly must proceed using the special tools; otherwise, damage to the engine could result. Caution 2: The engine must be completely cool when the cylinder heads are removed. Failure to allow the engine to cool off could result in cylinder head warpage. Caution 3: The manufacturer states that the cylinder head cannot be machined in the event of warping. If the cylinder head warpage exceeds 0.001 inch (0.0254 mm), it must be replaced.