Magazine for the auto service professional
Issue link: http://asp.epubxp.com/i/684411
47 | ASP June 2016 Technical was designed to use a gasket may or may not seat properly if RTV or another liquid or gel sealant is applied instead of a formed gasket. Tere are many instances where a liquid or gel sealant may be successfully used in place of a cut gasket, as long as the fnal torque value and clamping load doesn't move the component too close to the opposite mating surface. Cut/pre-formed gaskets not only provide sealing between mating surfaces, but also provide a specifc spacing between the mating surfaces. In other words, the type of sealing product can infuence dimensional characteristics. Tis spacing distance from one component to another can either ofer a degree of latitude, or it can be critical, depending on the specifc application. As an extreme example, let's consider the camshaft caps on an overhead-cam engine that might require no sealant or a "packing" sealant liquid between the caps and cylinder head. If a mechanical gasket was placed between the caps and head, this would raise the caps up, creating an out-of-round and excessive oil gap between the camshaft's journals and cam bores. Our point is that not all mating surface areas require a mechanical gasket. When in doubt, refer to the vehicle's service manual. Sealing problem areas When installing formed bead-type gaskets, as found on many late model valve covers, thermostat housings, and O-ring style intake manifold seals, consider applying a light coat of lubricant such as Vaseline or white lithium grease. Tis will aid in both holding the gasket in place during installation and will allow the material to slide and more easily conform into place during component installation, reducing the chance of tearing or mis-locating the gasket. Before installing bead style or O-ring style gaskets into retaining grooves, take the time to make sure that the retention groove is absolutely clean and free of dirt particles or other obstructions that will hinder proper seating. Pay attention to areas where corners and intersecting mating surfaces are involved. An example is where each side of a timing cover meets both the block and oil pan. In addition to the appropriate gaskets, a very small dab Many of today's OE engines such as GM's LS series feature front and rear cast aluminum covers. The lower edges of these covers must mate squarely to the oil pan. Before tightening front or rear cover bolts, verify fush surface alignment with the block's pan rails. Prior to installing the pan, apply a dab of RTV in each corner where the oil pan, block rail and cover corners meet. Coolant transfer tubes that feature O-ring seals require careful installation to avoid nicking or cut- ting the O-rings. Apply a thin coat of lithium grease or Vaseline to the O-ring to ease installation. Sensors that feature O-ring seals can easily cause leaks if the O-ring is damaged during installa- tion. Lightly lube O-rings prior to installation, and make sure that sensor holes are clean.