A head gasket on a Shovelhead engine refers to the gasket between the cylinder head and the cylinder or engine block. The purpose of the head gasket is to provide optimal compression and prevent fluid leaks. If a head gasket fails, the motorcycle can lose power, or the engine can be overworked or even damaged. A failed head gasket will cause the engine to not accelerate properly or idle roughly. If any of these symptoms occur, stop riding the motorcycle and fix it promptly.
1. Remove the spark plug wires by pulling on the head of the wire. Label the wires using masking tape and a pencil for reconnection.
2. Remove the spark plugs using a socket and ratchet.
3. Disconnect the oil lines from the rocker arm cover and cylinder heads. There are two oil lines: one on the left side of the rocker arm cover and one coming out of the right side of the rocker arm cover. Loosen the nuts connecting the lines to the rocker arm cover using an adjustable wrench. Once the nuts are loosened, the lines can be moved away from the rocker arm cover. Label the lines and their connection points on the rocker arm cover.
4. Remove the pushrods. Place the head of a flathead screwdriver against the pushrod cover spring retainer and push down. This pushes the tab locking the pushrod in place out of the way and allows for removal of the pushrod. Repeat this for the second pushrod.
5. Remove the bolts on the cylinder head using a socket and ratchet. Remove the bolts in a crossing pattern. For example, remove the upper left bolt, then remove the lower right bolt. The size of the socket and ratchet needed is determined by the year of the bike. Refer to the owner’s manual for the specific sizes.
6. Strike the cylinder head with a rubber mallet to loosen it from its position.
7. Lift the cylinder head to remove it from the cylinder. The rocker arm is still connected to the cylinder head and should remain so.
8. Remove the cylinder head gasket by pulling it off.
9. Clean the surfaces on the cylinder head and cylinder where the gasket fits using a rag and carburetor cleaner. If the residue is difficult to remove, use a razor to scrape it off. Make sure nothing falls into the cylinder.
10. Install the new cylinder head gasket. Make sure the holes for the oil return in the gasket and the cylinder head line up.
11. Coat the threads of the bolts connecting the cylinder head to the cylinder with motor oil. Reinstall the bolts and finger-tighten.
12. Tighten the bolts in the crossing pattern described in Step 5 to the torque specifications in the owner’s manual.
13. Reinstall the pushrods.
14. Reconnect the oil lines. Check the oil level and refill as necessary.