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Halderman ch029 lecture
 

Halderman ch029 lecture

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  • Figure 29-1 An air-powered grinder attached to a bristle pad being used to clean the gasket surface of a cylinder head. This type of cleaning pad should not be used on the engine block where the grit could get into the engine oil and cause harm when the engine is started and run after the repair.
  • Figure 29-2 An abrasive disc commonly called by its trade can be engine damaging. name, Scotch Brite™ pad.
  • Figure 29-3 Using baking soda is the recommended way to clean engine parts because any soda that is left on or in the part is dissolved in oil or water, unlike either sand or glass beads, which can be engine damaging.
  • Figure 29-4 Small engine parts can be blasted clean in a sealed cabinet.
  • Figure 29-5 A pressure jet washer is similar to a large industrialsized dishwasher. Each part is then rinsed with water to remove chemicals or debris that may remain there while it is still in the tank.
  • Figure 29-6 A microbial cleaning tank uses microbes to clean grease and oil from parts.
  • Figure 29-7 (a) A pyrolytic (high-temperature) oven cleans by baking the engine parts. After the parts have been cleaned, they are then placed into an airless blaster. This unit uses a paddle to scoop stainless steel shot from a reservoir and forces it against the engine part. The parts must be free of grease and oil to function correctly.
  • Figure 29-7 (b) This cleaned engine block has been baked and shot blasted.
  • Figure 29-8 An ultrasonic cleaner being used to clean fuel injectors.
  • Figure 29-9 The top deck surface of a block is being tested using magnetic crack inspection equipment.
  • Figure 29-10 If the lines of force are interrupted by a break (crack) in the casting, then two magnetic fields are created and the powder will lodge in the crack.
  • Figure 29-11 This crack in a vintage Ford 289, V-8 block was likely caused by the technician using excessive force trying to remove the plug from the block. The technician should have used heat and wax, not only to make the job easier, but also to prevent damaging the block.
  • Figure 29-12 To make sure that the mark observed in the cylinder wall was a crack, compressed air was forced into the water jacket while soapy water was sprayed on the cylinder wall. Bubbles confirmed that the mark was indeed a crack.
  • Figure 29-13 A cylinder head is under water and being pressure tested using compressed air. Note that the air bubbles indicate a crack.
  • Figure 29-14 (a) Before welding, the crack is ground out using a carbide grinder.
  • Figure 29-14 (b) Here the technician is practicing using the special cast-iron welding torch before welding the cracked cylinder head.
  • Figure 29-14 (c) This is the finished welded crack before final machining.
  • Figure 29-14 (d) Note the finished cylinder head after the crack has been repaired using welding.
  • Figure 29-15 Reaming a hole for a tapered plug.
  • Figure 29-16 Tapping a tapered hole for a plug.
  • Figure 29-17 Screwing a tapered plug in the hole.
  • Figure 29-18 Cutting the plug with a hacksaw.
  • Figure 29-19 Interlocking plugs.
  • Figure 29-20 (a) A hole is drilled and tapped for the plugs.
  • Figure 29-20 (b) The plugs are installed.
  • Figure 29-20 (c) After final machining, the cylinder head can be returned to useful service.

Halderman ch029 lecture Halderman ch029 lecture Presentation Transcript

  • ENGINE CLEANING AND CRACK DETECTION 29
  • Objectives
    • The student should be able to:
      • Prepare for ASE Engine Repair (A1) certification test content area “A” (General Engine Diagnosis).
      • List the types of engine cleaning methods.
      • List the various methods that can be used to check engine parts for cracks.
      • Describe crack repair procedures.
  • INTRODUCTION
  • Introduction
    • After disassembly, all engines must go through two operations
      • All parts thoroughly cleaned
      • All parts inspected to ensure they are free from faults such as cracks
  • MECHANICAL CLEANING
  • Mechanical Cleaning
    • Principles
      • Remove heavy deposits by scraping, abrasive brushing, abrasive blasting
  • Mechanical Cleaning
    • Scraping
      • Putty knife most frequently used
        • Broad blade avoids scratching surface of parts
      • Plastic card used to clean aluminum parts
  • Mechanical Cleaning
    • Abrasive Pads or Discs
      • Used on disassembled parts only
      • Do not use steel wire brushes on aluminum parts
  • Mechanical Cleaning
    • Abrasive Pads or Discs
      • After use, clean part to remove particles from pad or disc
        • White disc: finest grit
        • Yellow disc: coarse grit
        • Green disc
  • Figure 29-1 An air-powered grinder attached to a bristle pad being used to clean the gasket surface of a cylinder head. This type of cleaning pad should not be used on the engine block where the grit could get into the engine oil and cause harm when the engine is started and run after the repair.
  • Figure 29-2 An abrasive disc commonly called by its trade can be engine damaging. name, Scotch Brite™ pad.
  • Mechanical Cleaning
    • Media Blasting
      • Media blasting with baking soda cleaning method of choice
        • Nontoxic
        • Nonflammable
        • Nonhazardous
        • Environmentally safe
  • Mechanical Cleaning
    • Media Blasting
      • Soda blasting machine uses compressed air to clean part
      • Cleaning with solvents or heat requires second operation for uniform surface finish
        • Blast part with stainless steel shot, baking soda, or glass beads
  • Mechanical Cleaning
    • Media Blasting
      • Cleaning with solvents or heat requires second operation for uniform surface finish
        • Achieves matte or satin finish on part
        • Blasting particles must be absolutely dry so won’t stick to part
  • Figure 29-3 Using baking soda is the recommended way to clean engine parts because any soda that is left on or in the part is dissolved in oil or water, unlike either sand or glass beads, which can be engine damaging.
  • Figure 29-4 Small engine parts can be blasted clean in a sealed cabinet.
  • CHEMICAL CLEANERS
  • Chemical Cleaners
    • pH
      • Chemical cleaners used on carbon-type deposits are strong soaps
      • pH value indicates amount of chemical activity in soap
  • Chemical Cleaners
    • pH
      • Measured on a scale from 1 to 14
      • Pure water neutral (pH of 7)
  • Chemical Cleaners
    • pH
      • Caustic materials have pH of 8 to 14
        • Higher number, stronger caustic action
  • Chemical Cleaners
    • pH
      • Acid materials have pH of 1 to 6
        • Lower number, stronger acid action
  • Chemical Cleaners
    • pH
      • Caustic and acid materials neutralize each other
        • Baking soda (caustic) used to clean outside of battery (acid)
      • Use eye protection whenever working with chemicals
  • Chemical Cleaners
    • Solvent-Based Cleaning
      • Cleaning chemicals mix with and dissolve deposits
      • Loosen deposits so they can be brushed or rinsed from surface
  • Chemical Cleaners
    • Solvent-Based Cleaning
      • Can involve spray washer or a soak in cold or hot tank
      • Also contain silicates to protect aluminum against corrosion
  • Chemical Cleaners
    • Solvent-Based Cleaning
      • Strong caustics excellent for cast-iron items
      • Mineral spirit solvents and alkaline detergents used for aluminum
  • Chemical Cleaners
    • Water-Based Chemical Cleaning
      • Most chemical cleaning now uses water-based solutions
      • May be sprayed on or used in soaking tanks
      • Aluminum heads and blocks usually require overnight soaking
  • SPRAY AND STEAM WASHING
  • Spray and Steam Washing
    • Spray Washing
      • High-pressure washer dislodges dirt and grime from engine surface
      • Typically performed in an enclosed washer
      • Faster than soaking
  • Figure 29-5 A pressure jet washer is similar to a large industrialsized dishwasher. Each part is then rinsed with water to remove chemicals or debris that may remain there while it is still in the tank.
  • Spray and Steam Washing
    • Steam Cleaning
      • Steam vapor mixed with high-pressure water and sprayed on parts
      • Heat of steam plus force of water perform cleaning
  • Spray and Steam Washing
    • Steam Cleaning
      • Must be used with extreme care
      • Usually caustic cleaner added as well
      • Mixture so active that can remove paint
  • THERMAL CLEANING
  • Thermal Cleaning
    • Temperatures Involved
      • Heat vaporizes and changes dirt, oil, and grease into dry, powdery ash
      • Best suited for cast iron, temperatures as high as 800°F (425°C)
      • Aluminum should not be heated to over 600°F (315°C)
  • Thermal Cleaning
    • Advantages
      • Cleans inside as well as outside of casting or part
      • Waste generated is nonhazardous and is easy to dispose of
  • Thermal Cleaning
    • Microbial Cleaning
      • Microbes that “eat” hydrocarbons off of parts
      • Environmentally friendly, but slower to clean parts
  • Figure 29-6 A microbial cleaning tank uses microbes to clean grease and oil from parts.
  • Thermal Cleaning
    • Pyrolytic Oven
      • Decomposes dirt, grease, and gaskets with heat like self-cleaning oven
      • Least hazardous method
      • Becoming most popular because no hazardous waste
  • Figure 29-7 (a) A pyrolytic (high-temperature) oven cleans by baking the engine parts. After the parts have been cleaned, they are then placed into an airless blaster. This unit uses a paddle to scoop stainless steel shot from a reservoir and forces it against the engine part. The parts must be free of grease and oil to function correctly.
  • Figure 29-7 (b) This cleaned engine block has been baked and shot blasted.
  • TANK AND VAPOR CLEANING
  • Tank and Vapor Cleaning
    • Cold Tank Cleaning
      • Removes grease and carbon
      • Disassembled parts completely covered by solution in tank
  • Tank and Vapor Cleaning
    • Cold Tank Cleaning
      • After soaking, parts are rinsed
      • Parts may be covered with thin layer of oil to prevent rusting
  • Tank and Vapor Cleaning
    • Cold Tank Cleaning
      • Parts washers often used in place of soaking tanks
      • May pump cleaning solution over parts to help remove dirt
  • Tank and Vapor Cleaning
    • Hot Tank Cleaning
      • For cleaning heavy organic deposits and rust from iron and steel parts
      • Caustic cleaning solution heated to near 200°F (93°C)
      • Rapid cleaning action
  • Tank and Vapor Cleaning
    • Vapor Cleaning
      • Parts suspended in hot vapors above perchloroethylene solution
      • Vapors of solution loosen soil from metal
      • Soil can be blown, wiped, or rinsed from surface
  • ULTRASONIC AND VIBRATORY CLEANING
  • Ultrasonic and Vibratory Cleaning
    • Ultrasonic Cleaning
      • Used to clean small parts that must be absolutely clean
      • Parts placed in cleaning solution that is vibrated at ultrasonic speeds
      • Soil is loosened and falls into solution
  • Figure 29-8 An ultrasonic cleaner being used to clean fuel injectors.
  • Ultrasonic and Vibratory Cleaning
    • Vibratory Cleaning
      • Best suited for small parts
      • Parts loaded into a vibrating bin with media and cleaning solution
      • Movement of vibrating solution and scrubbing action of media clean metal
  • CRACK DETECTION
  • Crack Detection
    • Visual Inspection
      • After cleaning, reexamine parts for faults
      • Use magnifying glass
  • Crack Detection
    • Visual Inspection
      • Internal parts with cracks should be replaced
      • Cracks in blocks and heads can be repaired
  • Crack Detection
    • Magnetic Crack Detection
      • Commonly called by brand name: Magnafluxing
      • Method most often used on steel and iron components
  • Crack Detection
    • Magnetic Crack Detection
      • Part connected to strong electromagnet
      • Magnetic lines of force concentrate on the edges of a crack
      • Fine iron powder applied, attracted to magnetic concentration
  • Figure 29-9 The top deck surface of a block is being tested using magnetic crack inspection equipment.
  • Figure 29-10 If the lines of force are interrupted by a break (crack) in the casting, then two magnetic fields are created and the powder will lodge in the crack.
  • Figure 29-11 This crack in a vintage Ford 289, V-8 block was likely caused by the technician using excessive force trying to remove the plug from the block. The technician should have used heat and wax, not only to make the job easier, but also to prevent damaging the block.
  • Crack Detection
    • Dye-Penetrant Testing
      • Often used on pistons and other parts made of nonmagnetic material
      • Dark red penetrating chemical sprayed on component
  • Crack Detection
    • Dye-Penetrant Testing
      • After cleaning, white powder sprayed over test area
      • If crack present, red dye will stain white powder
  • Crack Detection
    • Fluorescent-Penetrant Testing
      • Requires a black light
      • Can be used on iron, steel, or aluminum parts
      • Cracks show up as bright lines when viewed with a black light
  • Crack Detection
    • Pressure Testing
      • Cylinder heads and blocks often pressure tested with air
      • Check for leaks
  • Figure 29-12 To make sure that the mark observed in the cylinder wall was a crack, compressed air was forced into the water jacket while soapy water was sprayed on the cylinder wall. Bubbles confirmed that the mark was indeed a crack.
  • Figure 29-13 A cylinder head is under water and being pressure tested using compressed air. Note that the air bubbles indicate a crack.
  • Crack Repair
    • Crack Concerns
      • Cracks in engine block can allow coolant and oil to mix
      • Cracks in head allows coolant to leak into engine
  • CRACK REPAIR
  • Crack Repair
    • Crack Concerns
      • Cracks in head allows combustion gases to leak into coolant
      • Cracks across valve seat cause hot spots on valve
      • Head with crack has to be replaced or repaired
  • Crack Repair
    • Stop Drilling
      • Hole drilled at each end of crack to keep it from extending farther
      • Cracks cannot cross oil passages, bolt holes, or seal surfaces
  • Crack Repair
    • Crack-Welding Cast Iron
      • Takes great skill to weld cast iron
      • Can be done satisfactorily when entire cast part is heated red-hot
      • New technique involves flame welding using special torch
  • Figure 29-14 (a) Before welding, the crack is ground out using a carbide grinder.
  • Figure 29-14 (b) Here the technician is practicing using the special cast-iron welding torch before welding the cracked cylinder head.
  • Figure 29-14 (c) This is the finished welded crack before final machining.
  • Figure 29-14 (d) Note the finished cylinder head after the crack has been repaired using welding.
  • Crack Repair
    • Crack-Welding Aluminum
      • Aluminum can be welded using a special Heli-arc or similar welder
      • Crack cut or burned out before welding
  • Crack Repair
    • Crack Plugging
      • Crack closed using interlocking tapered plugs
      • Used in both aluminum and cast-iron engine components
  • Crack Repair
    • Crack Plugging
      • Ends of crack center punched and drilled
      • Hole reamed with tapered reamer
  • Crack Repair
    • Crack Plugging
      • Hole then tapped with special tap to give full threads
      • Plug coated with sealer and tightened into hole; excess broken off
  • Crack Repair
    • Crack Plugging
      • Next hole drilled to interlock with preceding plug
      • Process continues to fill crack
      • Surface of plugs ground down to level with original surface
  • Figure 29-15 Reaming a hole for a tapered plug.
  • Figure 29-16 Tapping a tapered hole for a plug.
  • Figure 29-17 Screwing a tapered plug in the hole.
  • Figure 29-18 Cutting the plug with a hacksaw.
  • Figure 29-19 Interlocking plugs.
  • Figure 29-20 (a) A hole is drilled and tapped for the plugs.
  • Figure 29-20 (b) The plugs are installed.
  • Figure 29-20 (c) After final machining, the cylinder head can be returned to useful service.
  • TECH TIP
    • The Ice Scraper Trick
      • Using a steel scraper can damage aluminum heads or block deck surfaces. To prevent damage, try using a file to sharpen a plastic ice scraper and then use this to scrape gaskets from aluminum engine parts. This method works very well.
    ? BACK TO PRESENTATION