08-17-2011, 12:06 AM
post #13 of 19 (permalink)
Join Date: Aug 2010
Location: Central Ohio USA
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Some websites you might find useful for reference:
Notes on the Troubleshooting and Repair of small Gasoline Engines and Rotary Lawn Mowers
Snip from last link:
Tools and supplies
While you probably did not purchase your lawn mower specifically for the joys of repairing it, there is always a chance that despite all your precautions, the blade will strike a rock that just happened to grow out of the ground when you weren't looking. Therefore, it makes sense to be prepared. Basic servicing of small engines doesn't require a $500 tool caddy. However, some basic hand tools and other items will be needed.
For most of the procedures described below, the basic set of items listed in the section: Tools and supplies will suffice. However, some of the following more specialized tools may be needed depending on how far you go:
- A good quality set of socket wrenches is essential. For small engine work, a 3/8" ratchet and a set of sockets from 1/4" to 1" as well as a special spark plug socket. Usually a deep 13/16" type - check for your particular engine(s) will suffice. A basic set from Sears (Craftsman) should be fine and will come with a lifetime replacement warranty as well! If you have never invested in a socket set, now is the time. Forget about those $4 specials, however, as they are generally worse than useless. A word to the wise: you really must have a socket set to do any kind of work on small engines. Slip-joint pliers or worse yet - ViseGrips(tm) - just will not do!
While open-end or box-end (closed) wrenches may be used for certain bolts, some simply are not accessible without a properly sized socket (like cylinder head bolts).
- An impact wrench may come in handy for removing those really stuck bolts and screws. These accept standard screwdriver bits and sockets (via an adapter) and convert a hammer blow to rotary motion. First try penetrating oil like Liquid Wrench(tm) and normal tools though.
- A variety of good quality screwdrivers - both straight and philips.
- Needlenose and utility pliers.
- Wire cutters and strippers.
- Ball-peen hammer or other metal hammer.
- Rubber mallet.
- Funnel, drain pan, plastic milk jug for used oil. These can be discards from the kitchen.
- Old rags, cotton swabs, paper towels, etc. for cleaning. An old but soft paint brush for getting dust and dirt our of various places.
- Wood blocks for propping things up or securing the blade or flywheel when loosening or tightening. Other drift (scraps) of wood and soft metal.
- Torque wrench. An adequate model that will work with your 3/8" sockets can be purchased for around $10. Setting the torque - tightness - on certain engine bolts is critical to proper operation and long life.
- Feeler gauge - a set of precise thickness strips or wires for setting spark plug and point gaps. The .020" and .030" sizes should suffice for basic maintenance.
- Flywheel puller - build or buy. See the sections starting with: Flywheel removal. If purchased, it must be one designed for your model engine, not just something you picked up in the hardware store marked 'flywheel puller'! Briggs and Stratton, Tecumseh, and others sell tools specifically for their engines. This is the easiest way to remove the flywheel.
- Carburetor cleaner - this comes in a spray can. It is also probably as flammable as gasoline, toxic, and will eat plastics and painted surfaces. Therefore, use only in a well ventilated area or outdoors and take appropriate precautions.
- A tube of thread-lock comes in handy as well as some anti-seize compound like graphite grease for the muffler/exhaust bolts and spark plug.
- Micrometer - many of the measurements of wear to engine parts requires determining the diameter of shafts or bearing surfaces. Except for the piston, most of these can be accommodated by a micrometer with a maximum opening of 1 to 1-1/4 inches. However, in many cases, what is important is not actual diameter but clearance - and this can be determined with the inexpensive 'plastigauge' or a substitute.
- Plastigauge - these are disposable pieces of calibrated plastic used to determine the critical clearance between the rod bearing and crank pin journal. You place one in between the rod bearing and crank pin journal and tighten to specifications. When removed, simple measurements on the markings on the squashed plastigauge will very precisely determine the clearance, taper, and out-of-round specifications for your bearing. It is also possible to obtain most of this information by using slips of paper or foil of known thickness but this will not be as accurate or convenient.
- Flatness gauge - a good machined straight-edge and a set of feeler gauges will suffice for checking the mating surfaces of the cylinder and head.
- Ridge reamer - the 1/8" or so above where the piston slides in the cylinder will develop a buildup of carbon. In addition, if the engine has seen really heavy use, the metal in this area will be higher (less worn) than the section below. In order to remove the piston, this ridge must be eliminated or else it either won't come out or you risk breaking the rings. Fortunately, the metal ridge is rarely a problem on lawn mower engines and the carbon ridge can be removed with a simple homemade tool which is just a soft metal (i.e., aluminum or brass) piece with a straight edge or inside right angle. You probably will not need an expensive commercial ridge reamer tool. You will not need one at all unless you will be removing the piston.
- Piston ring compressor - when reinstalling the piston and rings, it is virtually impossible to squeeze the rings together to fit into the cylinder without some help. Commercial piston ring compressors are available for about $5 or you can make your own from a large hose clamp and strip of sheet steel (say, 1" x 12" x .020"). This tool is not needed unless the piston is being removed from the cylinder.
- Piston ring expander - this allows the easy removal of piston rings from the piston. With care, you can do this by grabbing the two sections of the ring and guiding it off the piston by hand. In any case, unless you will actually be removing the rings from the piston, this tool will not needed.
- Valve spring compressor - in order to remove and reinstall the valves, their rather powerful spring must be squeezed together tightly. This is almost impossible to do without this tool. I have done it with an improvised clamp designed for holding lab equipment but it was barely up to the task and not fun. However, unless you are going to remove the valves, this tool will not be needed.
- Rubber mallet - the engine overhauler's 'persuader'. In particular, to break free the crankcase/oil sump joint and for reinstalling the piston using the piston ring compressor. A small one will be more than enough.
- Scrapers - to remove built up carbon deposits and stuck gasket material - start with a strip of aluminum. For stubborn deposits, a flat edge paint scraper or straight blade screwdriver will come in handy. Take care not to scratch any machined surfaces. Coarse steel wool can then be used to finish up after the major deposits have been removed. For fine work, an X-acto knife also is useful.
- Wood blocks (4" x 4" x 8" typical) for supporting the engine on your workbench.
- Rags, paper towels, and more rags. Just make sure to dispose of oil soaked material safely. Plenty of old newspaper to protect the ground or table top.
To attach a picture there are a couple of ways to do it. First way is after you click reply and the next screen comes up, scroll down and click the manage attachments button. From there you can upload the photo from your computer. If it's to big of a file you might have to reduce it's size using a photo editing program. Or you can send me a personal message I will give you my email address and you can send the photo to me and I can resize it for you.
Second way is to have an online photo storage accout with PhotoBucket (the one I use) or Flicker, etc. Those places give you a link after you upload the photo that you insert in the post to make it show up.
Last edited by Mark / Ohio; 08-17-2011 at 12:22 AM.