17.5 tecumseh egines
Older kohler engines, the ones that came on some of the older john deere and cub cadet models,side shaft models are still running,most have a set of points and condenser that a old ford 74 model and below would interchange with, and I have used them to replace them with,also the coil will interchange with them,less expensive than brand name, but just as good.
Small engine pistons have three rings,4 cycle engines that is.Lawnmowers, tillers, generators, air compressors and water pumps.The two top rings are compression rings, and the bottom ring is the oil ring and it is usually the one that wears out first,causing your engine to burn oil by not scraping the cylinder clean on the downward stroke,low oil or not changing the oil causes premature wear.Rings come in standard and over size, over size are used for worn cylinders.You can get them in.010,.020 and .030 thousandths over size.Usually standard size rings will work for a rebuild,one shade tree way to tell is to take the cylinder head off of engine,rotate piston all the way up and press your fingertips on piston and try to move it side to side againstcylinder wall, if you have substantial movement then its possible you would need .010 thousandths oversize,to make sure of no oil burning when you put engine back togetherWhen installing piston rings, you must stagger the ring gaps around piston in no certain order, just so no two line up, or otherwise compression and oil will blow by rings so to speak, that goes for all internal combustion engines.A ring compressor must be used to install piston back into cylinder,it will compress the piston rings back into piston enough to tap it back into cylinder, any other way and you risk breaking one of the rings, since they are breakable.To get piston rings for any small engine you will need model numbers from valve cover or flywheel cap, used to be just flywheel cover, but nowadays a lot of the model numbers are located on valve cover on briggs, kohler, tecumseh, honda, kawasaki.Constant white or blue smoke coming from a small engine is a troubleshooting sign of a worn oil ring and continued running in this condition for a season or so will cause the cylinder wall to be scarred,and the the cylinder must be honed to get rid of scarrs to ever stop burning oil even with new piston rings,more expense than worth a lot of times.
This past summer,I ran across some interesting thingsconcerning carbs and cams in Briggs an Strattonengines.First of all a customer brought a riding mower in with a12 hp Engine the complaint was that it was running wideopen whenever it was fired up.I immediately checked allof the linkages going to the carb,governor linkages andso forth.They checked out fineand if I had not seen this before, I would have beenstumped.What had happened and apparently was a defect thatBriggs was having on some of these engines.Thescrews that hold the butterfly in the carburetor in placehad vibrated out and were sucked into the engine,passed the valves, into the head and either they willimbede themselves into the soft aluminum head orpiston, or pass out the exhaust side.AT either rate theengine runs wide open because the butterfly cannotcontrol the gas flow .I had one that had sucked thebutterfly into the manifold, intake manifold.I have sawthis happen to several 12 and 14 hp engines, so I know ithas to be a defect of not putting enough loctite on thebutterfly screwsSecondly, a customer brought a 15 hp intek, Briggs anstratton in.The symptoms were,it would fire up and runon idle, but would not idle up.I checked the carb, andimmediately after finding it to be o.k. Proceeded toadjust the valves,being a overhead valve engine. Thatdone, the symptoms were no better.What washappening was the intake valve was letting fuel in, butthe exhaust valve was not staying open long enough tolet exhaust out,so Iput exhaust valve way out oftolerances to see what would happen, nochange.Immediately the possibility of a bad cam cameinto mind,but the engine was no more than two yearsold, then I saw made or assembled in Mexico on theflywheel cap.I pulled the engine, disassembled thebottom crankcase, pulled the cam and wala, one of thelobes was almost completely gone.The exhaust lobe tobe exact. I did this to two 15 hp inteks last season,soapparently there is a defect in some of the cams in thenewer engines,possibly its been solved by now.Also didthis on a 17 hp engine.Note; the replacement cams wereof much better quality.Hope these snippets of info will help you,if you runacross these type of things in the future.
Most of briggs side shaft engines from compressors to tillers have the tank style pulsa jet carb.One common problem is the diaphram will go bad, which is part of the pump mechanism on this type carburetor.One way to tell is if engine runs until half tank of fuel is used and then shuts off and will not start back until you fill tank completely full again,is an indication of a bad diaphram,a 95 cent part.
