QuestionI have an old kemp chipper shredder. I need to get off the flywheel. model 130202,type 8915-01,code 87120807. The engine is a 5 hp B&S. There is a gray metal piece where a protective screen screws on that appears like it might screw off itself before popping off the flywheel with a wheel puller.Is this is the case, does it screw off in a normal counterclockwise fashion or does it come clockwise?
Answerron
Flywheel removal
Remove the shroud (blower cover) if you have not done so already. This is usually fastened with 4 screws and hopefully does not involve any head bolts - if so, you will need to tighten them to the proper torque using a torque wrench once you have remedied the problem. You may need to remove the fuel tank (if you have not done this already) and other trim pieces as well.
You should now see the top of the flywheel. In most cases, a large nut fastens the flywheel to the crankshaft. (However, in some designs, part of the starter mechanism is actually used and this is supposed to require a special wrench to remove. However, using a piece of wood as a buffer and tapping the ears in a counterclockwise direction will work also. Refer to your engine manual for details.) Use the proper socket to loosen this nut (counterclockwise). It may be necessary to brace the flywheel securely to gain enough leverage. Make sure this is done against something that can stand the force. Once loose, remove it by hand and then remove any washers or other parts that are under it. Make a note of how these were positioned including which side is up on some cupped washers.
You should now see the keyway. The slots on the crankshaft and flywheel should be aligned. There are two common types of keys:
A rectangular or D shaped piece of soft metal that locks the flywheel and shaft. You should be able to see if the two identically sized slots are still aligned.
A piece of soft metal with an L-shaped cross section. The slot on the crankshaft is narrower than the slot on the flywheel and is slightly offset (thus, the L). Again, it should be obvious if the two slots are still aligned.
You may even find that the flywheel is relatively loose on the crankshaft if rotating the blade while holding the flywheel stationary is possible. Either the blade key or the flywheel key or both are broken in this case.
You will have to remove the flywheel to replace the key if it is broken or damaged.
If the flywheel is loose at this point, then the following will not be needed as it can be lifted off.
There are several approaches to flywheel removal:
The best way by far is to use a special puller designed for your particular engine. Briggs & Stratton and Tecumseh flywheels usually have 2 or 3 holes placed around the center of the flywheel which are used with special puller blocks. These have self tapping bolts which you thread into the holes and then tighten down nuts to pop the flywheel off of the crankshaft. I have made my own blocks for this purpose from scrap steel. If you have a drill press, it is not difficult. Alternatively, you can purchase these from the engine manufacturer. The use of a puller really does reduce the use of 4 letter expletives and virtually eliminates the chance of damage to the flywheel or crankshaft by the alternative techniques.
___ ___
|___| |___|<-------- Self tapping bolts or pretap holes.
| | | |
_|-|_ _|-|_
| |-| | | |-| |<------- Tighten nuts to release flywheel.
___|_|-|_|__________|_|-|_|___
| |-| |-| |<--- Plate or block - 1/4" or thicker steel
|_____|-|______________|-|_____|
|-| .-.----.-. |-|
|-| | :----: |<-|-|---------- Flywheel nut - loosen slightly.
|-| |_:----:_| |-|
______|-|___ :----: ___|-|______
//////:-:///|:----:|///:-://////
//////:-:///|:----:|///:-:////// <-- Flywheel comes with predrilled holes.
//////'-'///|:----:|///'-'////// (taper not shown - ASCII limitations!)
//////| |///|:----:|///| |//////
Bolts are screwed into holes in flywheel. Then, plate bears against the flywheel nut (slightly loosened) and the nuts are tightened alternately until the flywheel pops off.
WARNING: do not use an ordinary gear, clutch, pulley, bearing, or other puller unless this is specifically mentioned as a recommended technique in your engine manual. The flywheel could be damaged - possibly not immediately obvious - but the result could be catastrophic failure once the engine is put back into service.
A 'knock-off tool' is a special closed-end nut that you thread onto the crankshaft in place of the normal flywheel nut. You then are supposed to pry under the flywheel with a pair of large screwdrivers while tapping the knock-off tool with a soft hammer. Aside from the fact that as described, this requires 3 hands, this may or may not work easily. Depending on conditions, the flywheel may pop off at the first tap or may stubbornly refuse to budge no matter how much you whack. If not done properly, it is possible to bend the crankshaft - very expensive. Some people also worry that the shock will damage internal parts or even partially demagnetize the magnet on the flywheel. Thus, my preference for the puller unless the first couple of taps releases the flywheel.
Many engine books will simply recommend threading the flywheel nut back on flush with the end of the shaft and tapping this with a hammer as above (with the 3 hands). The risk here is that the threads may be damaged in addition to the possibility of bending the shaft or causing other damage. Use a piece of soft metal - aluminum, brass, or lead - to protect the end of the shaft and nut. In any case, only use this approach as a last resort.
