feb 235:03 pm filech.12.notebook 3 february 26, 2014 feb 235:18 pm keeping engines clean cleaning a...
TRANSCRIPT
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February 26, 2014
Feb 235:03 PM
Ch. 12
Preventative Maintenance and Troubleshooting
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February 26, 2014
Feb 235:15 PM
Why PM?
preventive maintenancecertain maintenance tasks must be performed regularly to keep an engine working properly
helps premature engine wear
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February 26, 2014
Feb 235:18 PM
Keeping Engines Clean
cleaning a small aircooled engine periodically can prevent overheating
If cooling fins are insulated by dirt, leaves, and/or grass clippings, engine parts will receive most of combustion heat
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Feb 235:19 PM
Parts (overheated)
Will expand, distort, and possibly seize
Clean all surfaces to the bare metal
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February 26, 2014
Feb 235:21 PM
Methods for Cleaning
blow debris from fins with compressed air and use a cleaning solvent
Scrape dirty areas with a piece of wood and wipe them off with a clean cloth
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February 26, 2014
Feb 235:23 PM
Checking Oil level and condition
crankcase oil in fourcycle engines should be checked periodically(each time fuel is added)
Use the type of visocity grade of oil recommended by manufacturer
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February 26, 2014
Feb 235:30 PM
Checking the Oil
withdraw dipstick, wipe it dry
Reinsert the dipstick, withdraw and observe oil level
All have low(add) and Full Mark
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February 26, 2014
Feb 235:31 PM
Add Oil if its on LOW
Do NOT run the engine if there is oil above the full mark
Overfilling will foul plugs and cause the engine to use too much oil
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Feb 235:36 PM
Engine Oil dropping at excessive rate
Typical causes:
External Leaks
Worn oil seals around crankshaft
Worn Valve Guides
Worn piston rings
Hot Running Engine
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February 26, 2014
Feb 235:38 PM
When to change oil
*Newonly after a few hours of running to remove any metallic particles from the crankcase
After that 1050 hours of running time
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February 26, 2014
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Engine Oildoes not wear out, always slippery
becomes contaminated with dirt particles, soot, sludge, varnishforming materials, metal particles, water, corrosive acids, and gasoline
The harm they cause outweighs the lubricating quality of the oil
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February 26, 2014
Feb 235:55 PM
Loaded Oilcannot absorb any more contaminants and still be an effective lubricant
when oil becomes loaded, varnish deposits begin to form on the piston and rings and sludge collects in the crankcase
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February 26, 2014
Feb 235:56 PM
Changing OilDisconnect spark plug
Oil drain plug is located at low point on crankcase, remove plug with proper wrench
Drain oil , replace plug
Change filter(if equipped)
Coat oring with light coat of clean oil, before new filter is put on
Pour new engine oil into crankcase, checking levels
Start and run engine for a few minutes
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February 26, 2014
Feb 236:02 PM
Mixing Oil and Fuel
can seriously damage engines by improper mixing
Proper wayPour gasoline into clean container first. Add oil to the gasoline and shake. Add the rest of the gasoline and shake again.
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February 26, 2014
Feb 236:06 PM
Condensation
forms in partially filled containers because of temperature changes.
During the day it warms up, holds moisture
At night, cools and loses water vapor
Each night, more water is added to fuel
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February 26, 2014
Feb 236:12 PM
Air cleaner service
carb air cleaner should be cleaned before each season of operation
a plugged air filter can cause hard starting, loss of power, and spark plug fouling
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February 26, 2014
Feb 236:15 PM
Crankcase breather service
should be removed and cleaned periodically
remove screws and cover
inspect reed valves
wash all parts in cleaning solvent
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February 26, 2014
Feb 236:19 PM
Muffler Service
Install a new one, check for improved efficiency
If designed to be taken apart, diassemble and clean in solvent
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February 26, 2014
Feb 236:20 PM
Water Cooling
water and metal produce chemical reactions, rust inhibitor should be added
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February 26, 2014
Feb 236:21 PM
Settlements
Scale settling to the bottom may clog passageways of water
No circulation will cause hotspots
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February 26, 2014
Feb 236:22 PM
Reverse Flushing(engine blocks, radiators)
Disconnect hoses from radiator and block
Force clean water in the opposite direction of circulation
Flush until water runs clear
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February 26, 2014
Feb 236:24 PM
Salt Water
Gearcase removed from water when not in use
Rinse engine with freshwater and wipe all lower unit parts with clean, oily cloth
Ignition leads and spark plug insulators should be wiped frequently to prevent accumulation of salt residue
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February 26, 2014
Feb 236:27 PM
Storing watercooled engines
During winter, antifreeze must be added to the water to protect against freezing (FLORIDA or down south)
Or DRAIN completely (tag engine)
YOU COULDCrack cylinder block, gearcase, damage water channels and tubes
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February 26, 2014
Feb 236:38 PM
Systematic Troubleshooting
Don't take whole engine apart
Troubleshootingnumber of steps you go through to find a problem
Basic principles
1.Test easiest things first
2. verify fundamental operating principles
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Easiest things first
Engine won't start?
Empty fuel tank? Disconnected spark plug wire?
Do not work on carburetor or ignition system until you have made a few basic checks
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Fundamental Operating RequirementsWhat are they?1. Proper carburetion
2. Correct ignition system operation
3. Adequate lubrication
4. Sufficient cooling
5. Proper compression
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Proper Carburetion
Clean, fresh fuel must be delivered in the correct proportion with combustion air
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Correct ignition system operation
Strong ignition spark must be precisely timed for best performance and efficiency
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February 26, 2014
Feb 236:48 PM
Adequate Lubrication
Proper amount of highquality lubricating oil must reach critical engine components
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Sufficient Cooling
Ample supply of cooling air, must reach engine
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Proper Compression
3045 psi minimum for starting and 90 psi minimum for efficient operation and sufficient power
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Reasoning & Troubleshooting
Use reasoning to make troubleshooting attempts at a specific area
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Feb 236:52 PM
Check RPMTest maximum idle rpm or governor RPM
Tachometeraimed at rotating part(reflective tape), handheld
Stroboscopehigh intensity light, measures rpm
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February 26, 2014
Feb 247:03 AM
Compression Checkfirst test determining the upper major mechanical parts of the engine
Procedure:1. Run engine until its warm
2. Disconnect all drives to the engine
3. Open choke and throttle valves wide
4. Remove the air cleaner
5. Remove spark plug and insert compression gauge
6. Crank the engine as fast as possible to obtain an accurate test
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February 26, 2014
Feb 247:06 AM
Less Compression than suggested?
Leaking Cylinder head gasket
Warped Cylinder head
Worn piston rings
Worn Cylinder bore
Damaged Piston
Burned or warped valves
Improper Valve Clearance
Broken or weak valve springs
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February 26, 2014
Feb 247:07 AM
Differential Pressure
DP test checks the compression of an engine by measuring leakage from the cylinder to the other parts of the engine
Designed to detect specific leakages so you don't have to disassemble whole engine
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February 26, 2014
Feb 247:09 AM
Differential Pressure Test1. Run the engine until it is warmed up to provide uniform lubrication to cylinder walls and rings
2. Remove spark plug wire and spark plug
3. Rotate the engine crankshaft until the piston of the cylinder being tested is at top dead center of the compression stroke. Both valves must be closed.
4. Thread adaptor into spark plug hole
5. Connect adaptor on rubber hose to quick disconnect fitting on tester.
6. Connect an air source of at least 90 psi to the tester adaptor.
7. Slowly adjust the regulated pressure gauge on the left with the regulator knob at 80 psi
8. the right handgauge indicates the relative pressure of the cylinder being tested
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February 26, 2014
Feb 247:17 AM
Service InformationBefore starting engine work, look at service manual
Manuals provide service procedures
Exploded views show assemblies and systems(diassemble and reassemble in correct order)
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February 26, 2014
Feb 247:19 AM
Troubleshooting Charts
List common causes and engine troubles along with common remedies(help)
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Tolerances and Clearances
Given in chart form in manuals/bulletins
When checking, adjusting spark plug gap, breaker point gap, ignition timing, this chart gives correct dimensions and piston locations
When chart shows two dimensions, it must be within range