What causes a flywheel key to shear?
Re: what causes a flywheel key to shear?? The key is shearing because you're asking it to hold the flywheel in place while running. The key should only be for locating the flywheel correctly before bolting it on. The fly wheel should be held on to the crank by pressing it onto the snout of the crank.
What are the symptoms of a sheared flywheel key?
A sheared flywheel key is a fairly frequent problem for small engines, particularly - but not limited to - those used on lawnmowers. Symptoms range widely from a little mis-fire to a no-start condition. WHAT IS A FLYWHEEL KEY? ^ Photo 1. Various Flywheel Keys
What keeps shearing on Briggs and Stratton 331877?
Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine So, the flywheel key keeps shearing on my 21 HP model Briggs and Stratton 331877-3036-G5 engine (on a Craftsman lawn tractor).
How does a flywheel key work?
The flywheel key is a small metal part (see Photo 1) that locates the flywheel in the correct position relative to the crankshaft, and thereby to the piston. A magnet mounted on the rotating flywheel moves past the ignition module (see Photo 7), induces a magnetic field in the module, which in turn delivers a spark to the spark plug.
Can a sheared flywheel key cause no spark?
0:143:17Lawnmower Will Not Start - You Will Never Guess Why! - YouTubeYouTubeStart of suggested clipEnd of suggested clipNow just because your flywheel key is sheared it does not mean that the engine will not start.MoreNow just because your flywheel key is sheared it does not mean that the engine will not start. Sometimes. They do run. People use them and they end up with a lot of oil like this on the engine.
How do you fix a key on a flywheel?
0:263:07Replacing the Flywheel Key on a Lawn Mower - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd the housing to keep the crankshaft from turning when you loosen the flywheel nut connect aMoreAnd the housing to keep the crankshaft from turning when you loosen the flywheel nut connect a socket wrench to the flywheel nut and tap it with a hammer to loosen the nut remove.
How do you remove a sheared flywheel key?
1:3511:47How to Fix a Sheared Flywheel Key! - YouTubeYouTubeStart of suggested clipEnd of suggested clipBasically you put the center shaft here onto your crank shaft of your engine. And then you put theMoreBasically you put the center shaft here onto your crank shaft of your engine. And then you put the jaws underneath. Your flywheel when it's bolted on to the engine.
Why do flywheels have fins?
The flywheel stores energy when torque is applied by the energy source, and it releases stored energy when the energy source is not applying torque. Today, the fins on flywheels act almost like fans, cooling the engine by distributing air around the engine block.
What holds the flywheel in place?
Virtually every flywheel or rotor is attached to the crankshaft by a taper on the crank, which matches the flywheel. Torque from the fixing bolt holds the flywheel securely on the shaft. Pulling a flywheel or rotor looks easy enough.
How do you remove a flywheel without a puller?
1:214:42How to Remove a Flywheel without a Puller on a Harbor Freight Predator ...YouTubeStart of suggested clipEnd of suggested clipAnyway put the the pipe eye underneath the flywheel. Apply some pressure take a ball-peen hammer.MoreAnyway put the the pipe eye underneath the flywheel. Apply some pressure take a ball-peen hammer. And hit the end of the crankshaft. And that's how you remove a flywheel without a flywheel puller.
What size is a Briggs and Stratton flywheel key?
Q: which are the dimensions for the flywheel key? A: The keys are rectangular in shape 1/8 X 3/16 X 5/8 They are made of aluminum.
How does a small engine flywheel Work?
0:003:02Flywheel - Explained - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo cars have fly wheels attached at the end of the engine or attached to the crankshaft. And it'sMoreSo cars have fly wheels attached at the end of the engine or attached to the crankshaft. And it's the item that will be pressed. Against with the transmission.
How does a lawn mower flywheel work?
0:396:10How Does A Lawn Mower Work? — Lawn Equipment Repair TipsYouTubeStart of suggested clipEnd of suggested clipThe flywheel has permanent magnets built into it and as it rotates past the ignition coil a magneticMoreThe flywheel has permanent magnets built into it and as it rotates past the ignition coil a magnetic.
Why do flywheels have magnets?
The flywheel magnet provides an electric charge to the ignition coil, in turn sparking the plug in a small engine. If the magnet has lost it's magnetic properties or comes loose, the small engine may not start or run properly.
What does a flywheel brake do?
Flywheel brakes are used to stop the flywheel from turning when a clutch has been disengaged and the motor is shutdown. Typically, these brake systems are installed on stamping, forging and metalforming equipment. Flywheel brakes are required for presses due to safety regulations.
Are small engine flywheels interchangeable?
First of all, the flywheels on Kohler K-series and Magnum engine models K241, M10, K301, M12, K321, M14, K341, M16 and K361 will interchange, because the tapers and keyway widths are the same. The only difference is the type of starter and ignition system used.
How does a flywheel key work?
The flywheel key shears to protect the crankshaft from twisting, which would cause a very expensive repair. A soft key allows the flywheel to move on the crankshaft when your mower blade hits a tree root, an old stump, a large dried clod of dirt, etc.
How do you keep a Woodruff key in place?
To keep a woodruff key in place while installing a mating component, ensure that it is situated tightly in the key seat. Since woodruff keys are made to tight tolerances, they often require a press fit into their seat.
How do you put a Woodruff key on a crankshaft?
8:2416:57Briggs & Stratton Small Engine Woodruff Key Replacement 690979YouTubeStart of suggested clipEnd of suggested clipGear you can now remove the old wood drift key from the crankshaft. If still intact to install theMoreGear you can now remove the old wood drift key from the crankshaft. If still intact to install the new woodruff key set it in the notch in the crankshaft. And use the flathead screwdriver.
How do you remove a Woodruff key?
You can try tapping a nail on one end of the key, drilling into the center of the key and removing it with a nail, or even heating the key up with a blowtorch and letting it cool repeatedly to loosen it. Remember that damaging the key is a far better alternative than damaging the shaft or other part around the key.
How to tell if a flywheel key is sheared?
Advanced timing can cause engine overheating. A muffler glowing cherry red probably indicates retarded timing. These variations depend on just how far the flywheel has spun out of time and in which direction. The key may have only partially sheared, or the flywheel may have advanced a half a revolution. If the sparks occurs during the compression stroke, the engine will backfire, and the crankshaft will reverse direction violently. If the operator was pulling the recoil starter, the starter rope would be pulled back sharply, along with the operator's arm. This is a common and painful occurrence, and a sure sign of a sheared flywheel key.
What is a sheared flywheel key?
A sheared flywheel key is a fairly frequent problem for small engines, particularly - but not limited to - those used on lawnmowers. Symptoms range widely from a little mis-fire to a no-start condition.
How to check flywheel key?
To get a good indication of the condition of the flywheel key, position the piston at top dead center and note the position of the flywheel magnet in relation to the ignition module. Top dead center can be found by removing the spark plug, touching a long screwdriver to the face of the piston and rotating the flywheel slowly by hand to the position where the screwdriver is extended out the spark plug hole by the maximum amount. A page showing the position of a few various flywheels at top dead center is included as a reference.
What is a flywheel key?
The flywheel key is a small metal part (see Photo 1) that locates the flywheel in the correct position relative to the crankshaft, and thereby to the piston. A magnet mounted on the rotating flywheel moves past the ignition module (see Photo 7), induces a magnetic field in the module, which in turn delivers a spark to the spark plug. The spark must be correctly timed to occur when the piston is near top dead center. The flywheel key determines the timing between the spark and the piston.
Why does my lawn mower have a sheared flywheel?
A sheared flywheel key is a frequent cause of a lawn mower engine no-start condition or poor running, often the result of hitting a rock, stump or other non-mowable ( non-movable? ) object. Flywheel keys are more likely to shear on lawnmowers because the crankshaft is solidly connected to the cutting blade which may strike an obstacle such as a rock or a stump, compared to other situations where the engine crankshaft is connected to the load ( e.g. pump, mower deck, tiller tines, drive wheels, etc. ) via a v-belt or coupling. The blade, crankshaft, and flywheel are spinning at about 3000 rpm, so when the blade hits an immovable object, the crankshaft decelerates suddenly but the flywheel doesn't want to stop so fast. Thus it shears the flywheel key. Since the flywheel continued to rotate relative to the crankshaft, the ignition timing is advanced. When pulling the starter rope the spark will fire during the compression stroke causing the piston and crankshaft to spin backwards. When this happens the rope handle may yank violently out of your hand and the recoil starter may possibly be damaged. This is a sure sign of a sheared flywheel key.
How to tell if a flywheel is at fault?
The only way to verify whether or not the flywheel is at fault is by inspection. To do so, the blower housing, recoil starter, and any decorative covers and trim pieces must be removed. Commonly, the fuel tank and oil fill tube must also be removed or moved aside. On many engines the keyways can be seen after removing the flywheel nut or bolt. If the keyway groove on both the flywheel and the crankshaft are visible and aligned exactly, then the key is good.
What is the end of a flywheel called?
The end of the crankshaft to which the flywheel is mounted is a precision machined taper. In the taper there is a groove, called a keyseat, cut lengthwise into the shaft (see Photo 2).
What happens if you shear the first key?
As said, once you shear the first one it causes damage. Shear the second one and it causes more damage, The third----etc. SO, check the tapers. They must be virtually perfect. The key slots must not be battered. If everything is still serviceable, proceed--
What to do after shearing a key?
Also..... after once shearing a key, the crankshaft and flywheel tapers must be cleaned up, get rid of the burrs, etc. If the flywheel can't set properly on the crankshaft taper it will loosen up and shear again. To torque, one needs the proper torque wrench and socket, and also a strap wrench so as to hold onto the flywheel.
What must a crank and flywheel taper be?
1. Crank and flywheel tapers must be shiny clean and smooth.
How to install a key on a car?
The key must be installed with the straight edge perfectly vertical with the engine's driveshaft, crankshaft, etc, not aligned with the crankshaft taper, and the flywheel must be properly torqued. There should be a notch in the key that must go up. The round part of the key goes in the crankshaft.
Why is my flywheel shearing?
The key is shearing because you're asking it to hold the flywheel in place while running. The key should only be for locating the flywheel correctly before bolting it on. The fly wheel should be held on to the crank by pressing it onto the snout of the crank. There are 2 possible problems. Either you're not torquing the flywheel bolt properly or the taper on the flywheel or crank is bad. If it's the taper you can try to fix it with some compound.
How long to smear flywheel?
Put a smear on the snout, set the flywheel on without a key, and rock. Turn it 30 degrees, and rock some more. Do this for 10-15 minutes. Add more paste occasionally. Be sure to clean all the paste off of everything before final assembly. The snout and flywheel must be spotlessly clean before reassembly.
Can you buy metric keys locally?
These are metric keys, if you live in a town like mine, you won't be able to buy one locally, except thru the dealer. You should always lap the flywheel to the snout, even if it's got a good fit. I use Clover Compound, but any decent automotive store will be able to sell you valve grinding paste.
Why is my key smearing the left?
Looking from undeneath the flywheel, if the key is smearing the left (counterclockwise) it is caused by a loose flywheel nut. If it's smearing to the right (clockwise), then it's caused by a sudden impact stopping the engine, like a blade hitting something or an object getting caught in the drive belt. Since this is on a rider, most impacts are ...
Does a 2003 17HP lawn tractor start fire?
17hp lawn tractor will not start just big back fire. 2003
What engine does the flywheel key work on?
Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine. So, the flywheel key keeps shearing on my 21 HP model Briggs and Stratton 331877-3036-G5 engine (on a Craftsman lawn tractor).
What key keeps shearing on Briggs and Stratton 331877-3036-G5 engine?
Re: Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine Monday, March 25, 2019 6:33 AM ( permalink ) 0. Running a rope into the cylinder is a good way to bend the valves and/or push rods.
