Magazine for the auto service professional
Issue link: http://asp.epubxp.com/i/684411
48 | ASP June 2016 Technical of RTV in these intersecting areas can aid in preventing an oil leak. We've all run into problem sealing areas that result from damaged mating surfaces, where a cam cover, timing cover, etc., may have been distorted, nicked or gouged. While the ideal cure would be to replace the damaged component, time and budget factors might prevent replacement. When an excessive gap is the source of a leak, a quick and inexpensive solution might be to apply a bead of sealant in that problem area. I've used high quality RTV sealants to address many such issues. Choosing a specifc sealant of course depends on the specifc application, in terms of location, anticipated operating temperature and pressure and the type of gas or liquid involved. Leading chemical sealant makers ofer a wide range of chemical sealants, each designed for a specifc type of application. Instead of grabbing just any tube of sealant, do yourself a favor and refer to the maker's application information to select the sealant that is most appropriate for the job at hand. Te application charts are worth the time it takes to read them, and will aid you in choos- ing precisely the correct chemical for the job. It's important to understand that not all RTVs, thread lockers, gasket makers and sealants are equal. A wide range of these chemicals have been developed to address very specifc types of applications. I can't stress this enough — visit the brand's website and look at the application charts! An exhaust gas leak between an exhaust manifold and cylinder head, or between the exhaust manifold's outlet to a pipe, can result from uneven mating surfaces (warped exhaust deck caused by previous uneven tightening). It also can cause small cracks or porosity in the exhaust manifold or corrosion at the mating surfaces. While resurfacing or replacing the ofend- ing components may be ideal, budget and time doesn't always allow the ideal. A high temperature RTV sealant that contains copper is often successfully used to remedy these small leaks. As an example, I've used Permatex high temperature Ultra Copper Any female threaded hole should be checked for cleanliness prior to reassembly, but this is critical for cylinder head bolt holes in the block deck. In addition to cleaning the threads, consider running a dedicated chaser tap. This will clean and restore threads without needlessly removing thread material. Chaser threads are available in all popular inch and metric sizes. A dedicated chaser tap is designed to clean and re-form existing threads, as opposed to a common cutting tap that's designed to remove material. It's always a good idea to run a chaser tap through all head bolt holes. If pipe thread tape is installed on an NPT ftting or plug, be sure to wrap the tape so that the end of the tape follows the direction of thread engage- ment. Otherwise the exposed end of the tape will begin to unravel during installation.