Engine Sealing and Reassembly

1. Engine Sealing and Reassembly

2. Gaskets • Materials • Cork • Rubber • Cork/Rubber • Paper • Fiber • RTV (Room Temperature Vulcanizing)

3. RTV • Made from silicone rubber • Form in place gasket material • Curing agent is the humidity in the air • Used at the factory for some applications • Comes in various formulations for various applications • “Sensor-safe” RTV must be used in applications that use an oxygen sensor • Use only where recommended by the manufacturer

4. Anaerobic Sealers • Made of polymerized plastic (liquid resin) • Form-in-place gasket material • Cures in an oxygen free environment • Works well in tight fitting metal to metal sealing surfaces • Compresses to a “zero thickness”

5. Head Gaskets • Most complex and critical gasket • Seals pressures up to 1000 PSI • Temperatures exceeding 2000 F • Clamping forces up to 200,000 PSI • Seal Oil and Coolant • Maintain a seal over a wide range of temperatures • Maintain a seal between metals with different expansion rates

6. Head Gaskets • Head and deck surfaces must be acceptably flat and with proper finish • Not too smooth or too rough • Head gaskets are often directional • Do not use any sealant unless specifically called for • Torque specs and procedures must be followed

7. Rear Main Seals • Three possible types • Rope • Oldest • Soak in oil before installation • Trim to proper length • Two-piece • Lip faces toward the crankcase • Offset the mating surface of the rear seal and the rear main cap • One piece • Lip goes toward the crankcase • May use a retaining plate or be retained by the main cap

8. Engine Reassembly • ALWAYS use the proper lubricant on bolt threads • NEVER squirt oil in the bolt hole – the oil can accumulate on the bottom of the hole and when the bolt is torqued the oil will hydraulically “bottom the bolt out” causing under-torqued fasteners or cracking the block

9. Bolt Stretch • As a bolt is tightened its length increases • This increase in length is what provides the clamping force • If bolt stretch can be directly measured, that is the most accurate way of tightening a fastener • If bolt torque must be used it is essential that the correct lubricant be used on the threads

10. Lubrication System Priming • The lubrication system MUST be primed before the engine is started for the first time • This fills all oil passages with oil and ensure the bearings will receive oil instantly on startup • Priming can be done by turning the oil pump with a special driver and a drill through the distributor hole, or by using an external oil pump hooked to an oil fitting

11. Startup • The carburetor bowl should be pre-filled with fuel or fuel lines purged of all air before startup • The ignition timing should be as close as possible before startup • As soon as the engine fires, engine RPM should be brought up to 2000 RPM to begin breaking in the cam if necessary • Synthetic oil should not be used for break-in (first 1000 miles) • After cam break-in oil and filter should be changed • Oil and filter may be changed again at 500 miles • The oil should then be changed every 3 months - 3000 miles