Inspect and test coolant; drain and recover coolant; flush and refill cooling system with recommended coolant; bleed air as required;
Lesson Plan forAUT 150-151 Maintenance and Light Repair Section A
Course HS Title: / Maintenance and Light Repair / 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 how to Inspect and test coolant; drain and recover coolant; flush and refill cooling system with recommended coolant; bleed air as required. 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. Students need to be able to perform this task to 100% accuracy. Incorrectly performing this task can lead to climate control concerns, safety problems, or create customer satisfaction issues.
Prepared By / School / Date:
Grade Level / No. Students / No.IEP's: / Lesson Length:
No. / Task
Inspect and test coolant; drain and recover coolant; flush and refill cooling system with recommended coolant; bleed air as required
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 inspect and test coolant; drain and recover coolant; flush and refill cooling system with recommended coolant; bleed air as required, and pass a written exam on the task with 100% 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
Teacher Designed Materials and Other Handouts
Instructor can use the content section of this plan to create a handout for the students.
Textbooks and Workbooks
Chris Johanson / Auto Heating and Air Conditioning / 2009 / Goodheart Wilcox / 314-317
Motor Information Systems / ASE Test Preparation Guide / 2009 / Prentice Hall/Pearson / 470-471
Web Addresses
Today's Class / Melior / www.todaysclass.com
Supplies
As Needed / Coolant / Various
Equipment
As Needed / Hydrometer, Refractometer, Test Strips / Various
Content/Presentation/Demonstration Outline
Inform students that for the most accurate level reading, they should check the coolant when the engine is cold. The coolant revel should be at the top of the radiator filler neck if the vehicle has a coolant recovery system. The coolant level should be about 1-2” (25-51 mm) below the neck if there is no recovery system. Also, tell students to check the reservoir bottle for the proper level of coolant. If necessary, they should add coolant. Tell them to be sure to use the proper kind of antifreeze as many newer vehicles use long-life antifreeze. Explain that adding conventional antifreeze to a system containing long-life antifreeze will shorten the service life of the coolant.
SAFETY WARNING: Follow the safety precautions before removing the pressure cap. Also, let them know that newer vehicles use pressurized reservoirs. It should be removed with the same caution as a standard pressure cap. Tell them to follow these rules: * Allow the engine to cool off for at least 20 minutes. If necessary, open the hood and use a shop fan to blow cool air through the radiator and across the engine surface. * Using several shop towels to protect your hands, crack the pressure cap loose (no more than 1/8 turn) and allow pressure to escape. * Wait at least five minutes. * Using the shop towels, turn the cap another 1/4 turn and make sure no pressure remains in the system. * Remove the pressure cap.
Instruct students that COOLANT CONDITION can be initially checked by visual observation. Tell students to remove the pressure cap after following safety precautions and observe the coolant in the system. If the coolant is clear to dark in color (dark green or dark blue, for example), it is in good condition. If the coolant is rust colored, it must be changed and the system flushed. If oil is floating on the top of the coolant, engine oil or transmission fluid may be leaking into the cooling system. Also, tell them to check for milky oil in the engine and transmission.
Explain that even if the coolant looks good, there may not be enough antifreeze present to keep the system from freezing in cold weather. Let them know that the only sure way to check the freezing point of the coolant is to use a hydrometer or refractometer.
Instruct students that to use a HYDROMETER, place the hose in the filler neck, then squeeze and release the bulb to draw in a sample of the coolant. Allow the pointer, floats, or balls in the hydrometer to stabilize, and then read the temperature on the hydrometer. Explain that some hydrometers have a temperature correcting feature and it may be necessary to add or subtract from the reading, depending on the temperature of the coolant.
Tell students that to use a REFRACTOMETER, take a small sample of coolant from the radiator, and then place a few drops on the refractometer lens. Inform them to look through the refractometer to get the freeze point reading.
Inform students that some shops now use TEST STRIPS to quickly check engine coolant. Chemical test strips can check coolant for freeze protection, as well as its alkalinity (acidity) or pH level. However, most test strips can only be used on conventional coolants. To use the test strips, tell students to remove one strip from the container. Let them know to be sure to close the container, as the color chart is often on the side. Next, have them dip the test strip in the engine coolant, making sure both test spots are immersed. Tell them to then remove the test strip and wait approximately 30 seconds, and then compare the two test sections to the color chart that comes with the strips.
Instruct students to observe the radiator and HEATER HOSE CONDITION. Tell them to look for bulges and swelled spots, cuts and abrasions, cracks, and leaks. Inform them to allow the engine to cool off and observe the hoses. Any hose that collapses as the engine cools is soft and should be replaced. As a final check, tell them to release system pressure and squeeze the hoses near the clamps to check for soft spots.
Explain that some hose damage may not be evident to the naked eye. Let them know that hoses are weakened over time by electrochemical degradation (ECD), which is a reaction between the chemicals in the coolant and the metals in the engine and radiator. Often, this reaction can cause hose defects. Because of this, tell students that coolant hoses should be changed if they are more than three years old. Explain that ECD has the greatest effect on heater hoses, bypass hoses, and the upper radiator hose.
Instruct students that improper grounding of electrical circuits can cause ELECTROLYSIS. Explain that electrolysis is the creation of an electric current in the cooling system. A multimeter can be used to check for electrolysis in the cooling system. Tell students to set the multimeter to the DC volts scale and connect the negative probe to the negative terminal of the vehicle’s battery. Place the positive probe into the coolant at the radiator filler neck and note the reading. As a general rule, tell students that the voltage reading should be between 0.1 and 0.4 volts. Let them know that any reading over 0.8 volts indicates a problem that should be fixed immediately.
Inform students that if the voltage reading is too high, remove one fuse at a time while monitoring the voltage reading. If voltage drops when a particular fuse is removed, the problem is in that circuit. Also tell them to check for missing ground wires. Let them know that in some cases, it may be necessary to operate electrical components while watching the multimeter. If the voltage jumps when a component is turned on, the component is not properly grounded.
To FLUSH the coolant system, instruct students to use the following information as a guideline:
Tell them to ensure that the engine is cold, and slowly remove the radiator cap. SAFETY WARNING: Remind them that if the radiator cap is removed from a hot cooling system, serious personal injury may result. Let them know that some coolant recovery tanks are pressurized. Tell them to relieve system pressure by loosening the cap on the recovery tank before removing the radiator cap.
Have them place a drain pan of adequate size under the radiator drain cock, then install one end of a tube or hose on the draincock and position the other end in the drain pan. They can then open the radiator draincock and allow the radiator to drain until the flow stops.
Next, tell students to place a drain pan of adequate size under the engine, and then remove the drain plug from the engine block and allow the engine block to drain until the flow stops. Inform students that there may be more drainage from the radiator at this time. After draining, tell students to close the radiator draincock and replace the engine block drain plug, and then remove the pans and dispose of the coolant a manner consistent with local regulations.
Instruct students to refill the cooling system with water and flushing agent. Remind them to carefully follow the directions provided by the manufacturer of the flushing agent. Tell them to start the engine and allow it to idle for the recommended time, and turn the vehicle heater to high and closely monitor the level in the radiator. After the recommended time has elapsed, tell students to turn the engine off Next, instruct them to open the drain plugs and observe the water as it drains. Explain that if the water doesn’t come out clear, they will need to repeat the procedure again until the water comes out clear.
Let them know that the length of this procedure varies depending on the condition of the cooling system and the number of times the cooling system must be flushed to remove the entire cleaning agent. Inform students that when the water does come out clear, close the drain plugs, and refill the cooling system with a 50-50 mixture of the proper type of antifreeze and clean water.
Let students know that many shops have pressure flushing and refilling machines. To use such a machine, tell them to use the manufacturer’s procedures rather than the information given here.
Instruct students that to BLEED the system, they will need to use one of the following procedures, depending on the relative placement of the engine and radiator.
Tell students that if the radiator is higher than engine, they should fill the system to about 3” (76 mm) below the top of the filler neck, and then allow the engine to reach operating temperature. Explain that when the thermostat opens, the radiator level will drop. Instruct them to add more coolant until the level is at the top of the filler neck (coolant recovery system) or 3” (76 mm) below the filler neck (no coolant recovery system).
If the engine higher than radiator, tell students to fill the system to about 3” (76 mm) below the top of the filler neck. Again, allow the engine to reach operating temperature. When the thermostat opens, tell students that the radiator level will drop. Instruct students to open the bleed valve(s) on the engine, and add more coolant until the coolant begins to exit from the bleed valve, then close the bleed valve and add coolant to fill the radiator. Let them know that on some vehicles, the bleeder may need to be opened and closed several times to remove all air from the system.
Instruct students that when this procedure is done, they should install the radiator cap, add coolant to the cold level on the coolant recovery reservoir, and clean up any spilled coolant.
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.)