Halderman ch036 lecture

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  • Figure 36-1 Gaskets are used in many locations in the engine.
  • Figure 36-2 Gaskets help prevent leaks between two surfaces.
  • Figure 36-3 A typical perforated steel core head gasket with a graphite or composite facing material.
  • Figure 36-4 A solid steel core head gasket with a nonstick coating, which allows some movement between the block and the head, and is especially important on engines that use cast-iron blocks with aluminum cylinder heads.
  • Figure 36-5 The armor ring can be made from steel or copper.
  • Figure 36-6 Multilayer steel (MLS) gaskets are used on many newer all-aluminum engines as well as on engines that use a cast block with aluminum cylinder heads. This type of gasket allows the aluminum to expand without losing the sealing ability of the gasket.
  • Figure 36-7 Left to right: Cork-rubber, paper, composite, and synthetic rubber (elastomer) gaskets.
  • Figure 36-8 Rubber-coated steel gaskets have replaced many oil pan gaskets that once had separate side rail gaskets and end seals.
  • Figure 36-9 Formed in place gaskets often use silicone rubber and are applied at the factory using a robot. Check gasket manufacturers for the correct gasket replacement.
  • Figure 36-10 A typical intake manifold gasket showing the metal washer at each fastener location which keeps the gasket from being compressed too much.
  • Figure 36-11 This intake manifold gasket was damaged due to fretting. Newer designs allow for more movement between the intake manifold and the cylinder head.
  • Figure 36-12 A rear main seal has to be designed to seal oil from leaking around the crankshaft under all temperature conditions.
  • Figure 36-13 Room-temperature vulcanization (RTV) is designed to be a gasket substitute on nonmachined surfaces. Be sure to follow the instructions as printed on the tube for best results.
  • Figure 36-14 Anaerobic sealer is used to seal machined surfaces. Always follow the instructions on the tube for best results.
  • Figure 36-15 The strength of the thread locker depends on whether the fastener is to be removed by hand (blue). High-strength thread locker (red) can only be removed if heated.
  • Figure 36-16 Applying antiseize compound to the threads of a bolt helps prevent the threads from galling or rusting.
  • Chart 36-1 Summary chart showing where sealants are used and their common trade names.
  • Halderman ch036 lecture

    1. 1. GASKETS AND SEALANTS 36
    2. 2. Objectives <ul><li>The student should be able to: </li></ul><ul><ul><li>Prepare for ASE Engine Repair (A1) certification test content area “C” (Engine Block Diagnosis and Repair). </li></ul></ul><ul><ul><li>Describe the various types of gaskets. </li></ul></ul><ul><ul><li>Explain why the surface finish is important for head gaskets. </li></ul></ul>
    3. 3. Objectives <ul><li>The student should be able to: </li></ul><ul><ul><li>List the types of sealers and their applications. </li></ul></ul><ul><ul><li>Explain the use and precautions associated with cover gaskets. </li></ul></ul>
    4. 4. INTRODUCTION
    5. 5. Introduction <ul><li>Need for Gaskets and Sealants </li></ul><ul><ul><li>Gaskets and sealants used to seal gaps between parts </li></ul></ul>
    6. 6. Introduction <ul><li>Need for Gaskets and Sealants </li></ul><ul><ul><li>Gaskets and sealants must withstand </li></ul></ul><ul><ul><ul><li>Temperatures equal to temperature parts are exposed to </li></ul></ul></ul><ul><ul><ul><li>Vibrations produced by engine and accessories </li></ul></ul></ul>
    7. 7. Introduction <ul><li>Need for Gaskets and Sealants </li></ul><ul><ul><li>Gaskets and sealants must withstand </li></ul></ul><ul><ul><ul><li>Acids and other chemicals found in and around engine </li></ul></ul></ul><ul><ul><ul><li>Expansion and contraction of engine parts </li></ul></ul></ul>
    8. 8. Figure 36-1 Gaskets are used in many locations in the engine.
    9. 9. HEAD GASKETS
    10. 10. Head Gaskets <ul><li>Requirements Needed </li></ul><ul><ul><li>Must withstand highest clamping loads </li></ul></ul><ul><ul><li>Must seal passages carrying coolant </li></ul></ul><ul><ul><li>Often required to seal passage carrying hot engine oil </li></ul></ul><ul><ul><li>Must seal combustion chamber </li></ul></ul>
    11. 11. Figure 36-2 Gaskets help prevent leaks between two surfaces.
    12. 12. Head Gaskets <ul><li>Requirements Needed </li></ul><ul><ul><li>Gasket must seal from -40°F (-40°C) to as high as 400°F (204°C) </li></ul></ul><ul><ul><li>Combustion pressure can reach 1,000 PSI (6,900 kPa) </li></ul></ul>
    13. 13. Head Gaskets <ul><li>Requirements Needed </li></ul><ul><ul><li>Cylinder head bolts are tightened to specified torque; these forces applied to head gasket </li></ul></ul><ul><ul><ul><li>Combustion pressure pushes head upward, reducing clamping pressure of head bolts when greatest seal is required of head gasket </li></ul></ul></ul>
    14. 14. Head Gaskets <ul><li>Requirements Needed </li></ul><ul><ul><li>Cylinder head bolts are tightened to specified torque; these forces applied to head gasket </li></ul></ul><ul><ul><ul><li>Partial vacuum during intake stroke pulls head down against gasket </li></ul></ul></ul><ul><ul><ul><li>As crankshaft rotates, force on head changes from vacuum to pressure </li></ul></ul></ul>
    15. 15. Head Gaskets <ul><li>Requirements Needed </li></ul><ul><ul><li>Newer engines have thin-wall castings </li></ul></ul><ul><ul><li>Castings are flexible and move as pressure changes </li></ul></ul>
    16. 16. Head Gaskets <ul><li>Requirements Needed </li></ul><ul><ul><li>Gasket must compress and recover to maintain seal </li></ul></ul><ul><ul><li>Head gaskets are made of several different materials depending on engine </li></ul></ul>
    17. 17. Head Gaskets <ul><li>Requirements Needed </li></ul><ul><ul><li>NOTE: Older head gasket designs often contained asbestos and required that the head bolts be retorqued after engine had been run to operating temperature. Head gaskets today are dense and do not compress like older-style gaskets. </li></ul></ul>
    18. 18. Head Gaskets <ul><li>Requirements Needed </li></ul><ul><ul><li>NOTE: Therefore, most head gaskets are called no-retorque-type gaskets, meaning the cylinder head bolts do not have to be retorqued after the engine has run. New gaskets do not contain asbestos. </li></ul></ul>
    19. 19. Head Gaskets <ul><li>Types of Head Gaskets </li></ul><ul><ul><li>Perforated Steel Core Gaskets </li></ul></ul><ul><ul><ul><li>Mesh core with fiber facings </li></ul></ul></ul><ul><ul><ul><li>Another design has rubber-fiber facings on solid steel core </li></ul></ul></ul>
    20. 20. Figure 36-3 A typical perforated steel core head gasket with a graphite or composite facing material.
    21. 21. Figure 36-4 A solid steel core head gasket with a nonstick coating, which allows some movement between the block and the head, and is especially important on engines that use cast-iron blocks with aluminum cylinder heads.
    22. 22. Head Gaskets <ul><li>Types of Head Gaskets </li></ul><ul><ul><li>Perforated Steel Core Gaskets </li></ul></ul><ul><ul><ul><li>Thickness of gasket controlled by thickness of metal core </li></ul></ul></ul><ul><ul><ul><li>Facing compensates for minor warpage and surface defects </li></ul></ul></ul><ul><ul><ul><li>Fiber facing protected around combustion chamber with metal armor (fire ring) </li></ul></ul></ul>
    23. 23. Figure 36-5 The armor ring can be made from steel or copper.
    24. 24. Head Gaskets <ul><li>Types of Head Gaskets </li></ul><ul><ul><li>Perforated Steel Core Gaskets </li></ul></ul><ul><ul><ul><li>Metal increases gasket thickness around cylinder to form tight combustion seal </li></ul></ul></ul>
    25. 25. Head Gaskets <ul><li>Types of Head Gaskets </li></ul><ul><ul><li>Multilayered Steel Gaskets </li></ul></ul><ul><ul><ul><li>Three to five layers of stainless steel sheet separated by elastomer material </li></ul></ul></ul><ul><ul><ul><li>Multiple layers of metal provide springlike effect allowing it keep combustion chamber sealed </li></ul></ul></ul>
    26. 26. Head Gaskets <ul><li>Types of Head Gaskets </li></ul><ul><ul><li>Multilayered Steel Gaskets </li></ul></ul><ul><ul><ul><li>Many layers of thin steel reduce bore and overhead camshaft distortion with less clamping force loss than previous designs </li></ul></ul></ul>
    27. 27. Figure 36-6 Multilayer steel (MLS) gaskets are used on many newer all-aluminum engines as well as on engines that use a cast block with aluminum cylinder heads. This type of gasket allows the aluminum to expand without losing the sealing ability of the gasket.
    28. 28. Head Gaskets <ul><li>Types of Head Gaskets </li></ul><ul><ul><li>Multilayered Steel Gaskets </li></ul></ul><ul><ul><ul><li>MLS gaskets reduce torque requirement and stress on fastener and engine block </li></ul></ul></ul>
    29. 29. Head Gaskets <ul><li>Types of Head Gaskets </li></ul><ul><ul><li>Multilayered Steel Gaskets </li></ul></ul><ul><ul><ul><li>MLS head gaskets are used on most engines with aluminum cylinder heads and cast-iron blocks </li></ul></ul></ul>
    30. 30. Head Gaskets <ul><li>Types of Head Gaskets </li></ul><ul><ul><li>Multilayered Steel Gaskets </li></ul></ul><ul><ul><ul><li>MLS head gaskets require both head and block deck to have smooth surface finish of 15 to 30 microinches </li></ul></ul></ul>
    31. 31. COVER GASKET MATERIALS
    32. 32. Cover Gasket Materials <ul><li>Cover Gasket Requirements </li></ul><ul><ul><li>Cover gaskets used to seal valve covers, oil pans, timing chain, and other covers </li></ul></ul><ul><ul><li>Cover gasket must be impermeable to fluids it seals </li></ul></ul>
    33. 33. Cover Gasket Materials <ul><li>Cover Gasket Requirements </li></ul><ul><ul><li>Cover gasket must conform to shape of surface </li></ul></ul><ul><ul><li>Cover gasket must be resilient </li></ul></ul>
    34. 34. Cover Gasket Materials <ul><li>Cork Gaskets </li></ul><ul><ul><li>Older engines often used cork gaskets </li></ul></ul><ul><ul><ul><li>Changes size while in storage or when installed in engine </li></ul></ul></ul><ul><ul><ul><li>Oil wicks through cork so it looks like it’s leaking </li></ul></ul></ul>
    35. 35. Cover Gasket Materials <ul><li>Cork Gaskets </li></ul><ul><ul><li>Older engines often used cork gaskets </li></ul></ul><ul><ul><ul><li>Later cork gaskets use synthetic rubber as binder for cork </li></ul></ul></ul><ul><ul><ul><li>Cork-rubber gaskets easy to use, longer lasting </li></ul></ul></ul>
    36. 36. Cover Gasket Materials <ul><li>Fiber Gaskets </li></ul><ul><ul><li>Covers with higher clamping forces use gaskets with fibers with greater density </li></ul></ul>
    37. 37. Cover Gasket Materials <ul><li>Synthetic Rubber Gaskets </li></ul><ul><ul><li>Molded, oil-resistant synthetic rubber </li></ul></ul><ul><ul><li>Operates at high temperatures for longer time than cork-rubber gasket </li></ul></ul>
    38. 38. Figure 36-7 Left to right: Cork-rubber, paper, composite, and synthetic rubber (elastomer) gaskets.
    39. 39. Cover Gasket Materials <ul><li>Rubber-Coated Metal Gaskets </li></ul><ul><ul><li>RCM gasket uses metal core for strength </li></ul></ul><ul><ul><li>Coated with silicone rubber and molded in sealing beads </li></ul></ul><ul><ul><li>Used for: </li></ul></ul><ul><ul><ul><li>Water pump gaskets </li></ul></ul></ul><ul><ul><ul><li>Valve cover gaskets </li></ul></ul></ul><ul><ul><ul><li>Oil pan gaskets </li></ul></ul></ul>
    40. 40. Figure 36-8 Rubber-coated steel gaskets have replaced many oil pan gaskets that once had separate side rail gaskets and end seals.
    41. 41. Cover Gasket Materials <ul><li>Formed in Place Gaskets </li></ul><ul><ul><li>FIPG are commonly used because they can be applied in engine plant by robot </li></ul></ul><ul><ul><li>Sealing material extruded onto sealing surface and parts placed together </li></ul></ul>
    42. 42. Figure 36-9 Formed in place gaskets often use silicone rubber and are applied at the factory using a robot. Check gasket manufacturers for the correct gasket replacement.
    43. 43. Cover Gasket Materials <ul><li>Plastic/Rubber Gaskets </li></ul><ul><ul><li>Most intake manifold gaskets use nylon reinforced body with silicone rubber surface </li></ul></ul><ul><ul><li>Nylon is used for two reasons </li></ul></ul><ul><ul><ul><li>Provides thermal barrier </li></ul></ul></ul><ul><ul><ul><li>Strong and provides stable foundation </li></ul></ul></ul>
    44. 44. Figure 36-10 A typical intake manifold gasket showing the metal washer at each fastener location which keeps the gasket from being compressed too much.
    45. 45. GASKET FAILURES
    46. 46. Gasket Failures <ul><li>Causes of Gasket Failure </li></ul><ul><ul><li>Detonation may cause extreme pressure causing gasket to deform </li></ul></ul><ul><ul><li>Plugged PCV system can increase crankcase pressure </li></ul></ul><ul><ul><li>Improper installation </li></ul></ul>
    47. 47. Gasket Failures <ul><li>Fretting </li></ul><ul><ul><li>Fretting caused by unequal expansion and contraction of engine materials </li></ul></ul>
    48. 48. Figure 36-11 This intake manifold gasket was damaged due to fretting. Newer designs allow for more movement between the intake manifold and the cylinder head.
    49. 49. OIL SEALS
    50. 50. Oil Seals <ul><li>Purpose and Function </li></ul><ul><ul><li>Oil seals allow shaft to rotate and seal area around shaft </li></ul></ul><ul><ul><li>Seals come in varied sizes and styles </li></ul></ul>
    51. 51. Oil Seals <ul><li>Seal Materials </li></ul><ul><ul><li>Most seals use steel backing plus sealing materials </li></ul></ul><ul><ul><ul><li>Buna-N </li></ul></ul></ul><ul><ul><ul><li>Viton ® (fluorocarbon) </li></ul></ul></ul><ul><ul><ul><li>Teflon ® (polytetrafluorethylene, also called PTFE) </li></ul></ul></ul>
    52. 52. Figure 36-12 A rear main seal has to be designed to seal oil from leaking around the crankshaft under all temperature conditions.
    53. 53. Oil Seals <ul><li>Seal Materials </li></ul><ul><ul><li>CAUTION: Do not use oil on Teflon ® seal because this type of seal requires that some of the material be transferred to the rotating shaft to seal properly. If oil is used on the seal, the seal will leak. </li></ul></ul>
    54. 54. ASSEMBLY SEALANTS
    55. 55. Assembly Sealants <ul><li>RTV Silicone </li></ul><ul><ul><li>Commonly used for sealing engines </li></ul></ul><ul><ul><li>RTV (room-temperature vulcanization) means silicone rubber material seals at room temperature </li></ul></ul>
    56. 56. Assembly Sealants <ul><li>RTV Silicone </li></ul><ul><ul><li>Cures to tack-free state in 45 minutes </li></ul></ul><ul><ul><li>Can be used as gasket substitute between a stamped cover and a cast surface </li></ul></ul><ul><ul><li>Can be used to fill gaps or potential gaps </li></ul></ul>
    57. 57. Assembly Sealants <ul><li>RTV Silicone </li></ul><ul><ul><li>RTV precautions </li></ul></ul><ul><ul><ul><li>Some RTV silicone sealers use acetic acid which can damage oxygen sensors </li></ul></ul></ul><ul><ul><ul><li>RTV should not be used with a gasket because it is slippery and may cause gasket to slip out of position </li></ul></ul></ul><ul><ul><ul><li>RTV silicone should never be used around fuel because fuel cuts through it </li></ul></ul></ul>
    58. 58. Figure 36-13 Room-temperature vulcanization (RTV) is designed to be a gasket substitute on nonmachined surfaces. Be sure to follow the instructions as printed on the tube for best results.
    59. 59. Assembly Sealants <ul><li>Anaerobic Sealers </li></ul><ul><ul><li>Anaerobic sealers cure in the absence of air </li></ul></ul><ul><ul><li>Used as thread lockers </li></ul></ul><ul><ul><li>Seal rigid machine joints between cast parts </li></ul></ul><ul><ul><li>Lose sealing ability above 300°F (149°C) </li></ul></ul><ul><ul><li>Special primers recommended on surfaces to get better bond </li></ul></ul>
    60. 60. Figure 36-14 Anaerobic sealer is used to seal machined surfaces. Always follow the instructions on the tube for best results.
    61. 61. Figure 36-15 The strength of the thread locker depends on whether the fastener is to be removed by hand (blue). High-strength thread locker (red) can only be removed if heated.
    62. 62. Assembly Sealants <ul><li>Nonhardening Sealers </li></ul><ul><ul><li>Form-A-Gasket 2 </li></ul></ul><ul><ul><li>Pli-A-Seal </li></ul></ul><ul><ul><li>Tight Seal 2 </li></ul></ul><ul><ul><li>Aviation Form-A-Gasket </li></ul></ul>
    63. 63. Assembly Sealants <ul><li>Nonhardening Sealers </li></ul><ul><ul><li>Brush Tack </li></ul></ul><ul><ul><li>Copper Coat </li></ul></ul><ul><ul><li>Spray Tack </li></ul></ul><ul><ul><li>High Tack </li></ul></ul>
    64. 64. Assembly Sealants <ul><li>Sealers are always used to seal threads of bolts that break into coolant passages </li></ul><ul><li>Sealers often recommended on shim-type head gaskets and intake manifold gaskets </li></ul><ul><li>Sealer may be used as sealing aid on paper and fiber gaskets </li></ul>
    65. 65. Assembly Sealants <ul><li>CAUTION: Sealer should never be used on rubber or cork-rubber gaskets. Instead of holding the rubber gasket or seal, it will help the rubber slip out of place because the sealer will never harden. </li></ul>
    66. 66. Assembly Sealants <ul><li>Antiseize Compounds </li></ul><ul><ul><li>Antiseize compounds are used on fasteners that are subjected to high temperatures to prevent seizing caused by galvanic action between dissimilar metals </li></ul></ul>
    67. 67. Figure 36-16 Applying antiseize compound to the threads of a bolt helps prevent the threads from galling or rusting.
    68. 68. Assembly Sealants <ul><li>Sealant Summary </li></ul>
    69. 69. Chart 36-1 Summary chart showing where sealants are used and their common trade names.
    70. 70. TECH TIP <ul><li>Wow! I Can’t Believe a Cylinder Can Deform That Much! </li></ul><ul><ul><li>An automotive instructor used a dial bore gauge in a 4-cylinder, cast-iron engine block to show students how much a block can deform. Using just one hand, the instructor was able to grasp both sides of the block and then squeeze it. </li></ul></ul>BACK TO PRESENTATION <ul><li>The dial bore gauge showed that the cylinder deflected about 0.0003 in. (3/10,000 of an inch) just by squeezing the block with one hand—and that was with a cast-iron block! </li></ul><ul><li>After this demonstration, the students were more careful during engine assembly and always used a torque wrench on each and every fastener that was installed in or on the engine block. </li></ul>
    71. 71. TECH TIP <ul><li>Rubber and Contact Cement </li></ul><ul><ul><li>One of the reasons why gaskets fail is due to their movement during installation. Some gaskets, such as cork or rubber valve cover gaskets or oil pan gaskets, can be held onto the cover using a rubber or contact cement. </li></ul></ul>BACK TO PRESENTATION <ul><li>To use a rubber or contact cement, use the following steps: </li></ul><ul><ul><li>STEP 1 Apply a thin layer to one side of the gasket and to the cover where the gasket will be placed. </li></ul></ul><ul><ul><li>STEP 2 Allow the surfaces to air dry until touch free. </li></ul></ul><ul><ul><li>STEP 3 Carefully place the gaskets onto the cover being sure to align all of the holes. </li></ul></ul><ul><ul><li>CAUTION: Do not attempt to remove the gasket and reposition it. The glue is strong and the gasket will be damaged if removed. If the gasket has been incorrectly installed, remove the entire gasket, clean the gasket surface, and repeat the installation using a new gasket. </li></ul></ul>
    72. 72. TECH TIP <ul><li>Hints for Gasket Usage </li></ul><ul><ul><li>Never reuse an old gasket. A used gasket or seal has already been compressed, has lost some of its resilience, and has taken a set. If a used gasket does reseal, it will not seal as well as a new gasket or seal. </li></ul></ul>BACK TO PRESENTATION <ul><li>A gasket should be checked to make sure it is the correct gasket. Also check the list on the outside of the gasket set to make sure that the set has all the gaskets that may be needed before the package is opened. </li></ul><ul><li>Read the instruction sheet. An instruction sheet is included with most gaskets. It includes a review of the things the technician should do to prepare and install the gaskets, to give the best chance of a good seal. The instruction sheet also includes special tips on how to seal spots that are difficult to seal or that require special care to seal on a particular engine. </li></ul>
    73. 73. TECH TIP <ul><li>Always Check the VIN </li></ul><ul><ul><li>There are so many variations in engines that it is important that the correct gasket or seal be used. For example, a similar engine may be used in a front-wheel-drive or a rear-wheel-drive application and this could affect the type or style of gasket or seal used. </li></ul></ul>BACK TO PRESENTATION For best results, the wise technician should know the vehicle identification number (VIN) when ordering any engine part.

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