3-35. Corrosion-Prevention. Prior to assembly of subassemblies, all parts should be cleaned to remove all traces of preservative oil and accumulated foreign matter. During assembly, cover all steel parts with a heavy coat of preservative oil. This mixture should be used on all machined surfaces, especially on bearing surfaces, cylinder bores and piston rings. The practive of using plain lubricating oil during assembly is not recommended.
3-36. Pre-Lubrication of Parts Prior to Assembly. Many premature failure of parts have been traced directly to im-proper pre-lubrication of engine assembly. If parts are not properly lubricated, or an inferior lubricant is used, many of the engine parts will become scored before the engine oil goes through its first cycle and has had a change to lubricate the engine. This, of course, will lead to premature parts failure prior to normal service life, and in some cases, lead to engine failure before normal service hours have been accumulated. It is of utmost importance, therefore, that the followingrecommendations be adhered to a engine assembly. Consult the latest edition of Service
Instruction No. 1059.
3-37. Coat the camshaft lobes, face of tappet bodies and rocker tips with lubri-bond (A) or equivalent.
3-38. Coat the valve stems and the interior of the valve guides with Texaco Molytex "0" or equivalent.
3-39. All other parts should be coated with a mixture of 15% pre-lubricant (STP or equivalent) and 85% SAE No. 50 mineral base aviation grade lubricating oil.
3-40. Olite Bushings. During overhaul cleaning operations it is possible to wash the oil from these bushings; also, if a bushing has been replaced and either reamed or broached, its porosity may be affected. Therefore, before the
Section 3 OVERHAUL MANUAL LYCOMING 76SERIES AIRCRAFT ENGINES
General Overhaul bushings are reassembled into the engine they must be impregnated by immersing then for at least fifteen minutes in engine oil that has been heated to 140°F.
3-41. It is strongly recommended that all overhaul
facilities adapt a firm policy of checking pitch alignment of bevel gears at the same time backlash is adjusted dur-ing engine overhaul.
3-42.Table of Limits. The table of limits SSP1776 should be consulted whenever it is desired to determine the backlash and end clearance of gears, the clearance bet-ween mating machined parts, the clearance between mating parts which are in close contact with each other and the torque limits for various nuts, screws and fasten-ings.
3-43.Oil Seals and Gaskets. When building up an engine during major overhaul, replace all oil seals and gasketsthroughout the engine. For complete replacement sets of seals and gaskets available for these engines, consult ap-plicable parts catalog.
3-44.Arbitrary Replacement of Parts. It is recommended that certain parts throughout the engine be replaced at normal overhaul regardless of their apparent condition. Consult the latest edition of Service Bulletin No. 240 for information on the replacing of parts at overhaul. Includ-ed among these are the following:
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