Clean and visually inspect a cylinder head for cracks; check gasket surface areas for warpage and surface finish; check passage condition.
Lesson Plan for
AUT 182-183/AUT 290
Automotive Service Technology Section A/Automotive Special Problems
Course HS Title: / Automotive Service Technology Section A/Automotive Special Problems / Program:KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No. / KCTCS Course Title
Introduction/Context / This lesson will instruct students on the proper procedures needed to clean and visually inspect a cylinder head for cracks; check gasket surface areas for warpage and surface finish, and check passage condition. Knowledge of these techniques and the skills required to correct problems associated with this task are necessary for a student to acquire if they wish to compete for high paying, high skilled jobs in an automotive repair facility. Entry level technicians need to be able to perform this task to 100% accuracy. Incorrectly performing this task can lead to drivability concerns, safety problems, or customer satisfaction issues.
Prepared By / School / Date:
Grade Level / No. Students / No.IEP's: / Lesson Length:
Task
Clean and visually inspect a cylinder head for cracks; check gasket surface areas for warpage and surface finish; check passage condition.
No. / Objective
1 / Given the proper tools and instructions from a vehicle manufacturers shop manual or automotive computer software program, students will be able to clean and visually inspect a cylinder head for cracks; check gasket surface areas for warpage and surface finish; check passage condition, and pass a written exam on the task with 100% accuracy by the end of the course.
Connections
Skills Standards:OH 001
OH 002
OH 003
OD 002
OD 003
OD 005
Common Core Technical Standards:
TD-SYS-2
New Common Core Standards:
RST 11-12.2
RST 11-12 3
INSTRUCTIONAL MATERIALS/TECHNOLOGY
Textbooks and Workbooks
Various / Automotive Excellence / Volume 2 2007 / Glencoe / ER 219-220
James E Duffy / Modern Automotive Technology / 2009 / Goodheart-Wilcox / 972-974
Web Addresses
Today's Class / Meilor / www.todaysclass.com
Equipment
As needed / Feeler gauge / Shop equipment
As needed / Magna flux crack checker / Shop equipment (or machine shop)
As needed / Straight edge / Shop equipment
Content/Presentation/Demonstration Outline
Instruct students that following cylinder head removal, a thorough cleaning of the head must be performed, including removal of all oil residue, carbon buildup, and gasket material. This may be accomplished by hand using gasket scrapers and the shop parts cleaner, or (if the shop is so equipped), by cleaning in a heated automatic parts washer. Care must be taken to prevent gouging or otherwise damaging aluminum cylinder heads. After cleaning a thorough inspection should be made, noting the condition of the head surface near the coolant passages. Deterioration in these areas is common.
Cylinder heads can be checked for straightness by using a straightedge, a shop light and a feeler gauge. After the cylinder head is cleaned place the straightedge on its edge on the bottom (block surface) of the head and place the light behind the straightedge. If light is visible below the straightedge, use the feeler gauge to measure the amount of warpage. Check the head in various positions, especially between combustion chambers, which is the most common place for warpage. The head will have to be sent to a machine shop for resurfacing if specs are exceeded (usually around .005, see specs for specific engine). This is common in engines that have been overheated. Care must be taken not to remove an excessive amount of material from the combustion chamber side of the head as this will increase compression ratio, and may cause valve train, sealing, or timing chain or belt issues. The surface finish is critical (especially in bi-metal engines, iron block and aluminum head) to insure long head gasket life.
Instruct students that a thorough cleaning and close visual inspection will find many cracks in cylinder heads. Common areas are between the valve seats, and around exhaust ports. But if a crack in suspected (coolant being lost gradually without evidence of why) it may be necessary (cast iron heads only) to use a magnaflux machine and metal fillings. Fillings are sprinkled on the clean head surface and the magnaflux machine (essentially a large magnet) is placed on the cylinder head. The magnetic field will cause the fillings to collect along any crack that may be there. Many machine shops will do this job if requested. Aluminum heads that are suspected of having an undetectable crack can be checked using a two-step dye process. A special dye penetrant is sprayed on the suspected area, and then a chemical developer is sprayed over the penetrant. The powder like developer will cause the dye to turn red making the crack show up. Cracks in cylinder heads can sometimes be repaired, depending upon severity and location of the crack. This can usually be handled by a competent automotive machine shop.
All cylinder head passages should be checked for any foreign object, manufacturer defects, cracks, and if threaded, the condition of the threads. Oil passages must be cleaned and, if the cylinder head is from an OHC engine the condition of the cam bearing surfaces should be inspected.
Applications/Practice
Evaluation and feedback Prior to Testing or Lab Work
STUDENT ASSESSMENT:(Assess student progress with performance criteria.)
IMPACT--Reflection/Analysis of Teaching and Learning: (How did students’ progress in relation to the state objectives? Was the instruction successful? Analyze samples of student work particularly that which is unsatisfactory, for the purpose of planning further instruction.)
REFINEMENT--Lesson Extension and Follow-up: (To be filled in as the lesson is modified during initial planning and/or during the teaching learning process.)