Lawn Mower Tune Up
How to do-it-yourself instructional on basic tune up of Tecumseh mower engine. Demonstrates troubleshooting a fouled spark plug and solving by increasing operating speed. Today on Repairs101 I've got my ten year old mower on blocks and I'm going to show you how to pim it out. just kidding. You don't have to block yours up as high as I did. put it up on a couple of bricks or on the edge of your workbench. first thing I'm going to tell you but not show you is "Run it dry". I run it dry every time. pull the sparkplug out pull the wire off, push it aside. socket wrench easy, spin it out have a look. quite clean some blackness but no large deposits. the insulator around electrode in centre, not cracked, Inspect insulator, here's the insulator. That's the electrode. sparkplug is blackened, a bit fouled. most likely cause overfuelling/ rich fuel condition. Reasons for a blackened spark plug include things like too rich fuel mixture or sticking choke or clogged air cleaner, anything going to increase the fuel in the fuel : air ratio. good possibility is oil seeping past the rings on the compression piston and getting up into the combustion chamber and fouling it. quick compression test had the sense to hold onto literature came with lawn mower ten years ago spark plug thirty-thou. thirty-thou nothing wrong with gap. Clean it up with a soft wire brush reuse it. looked around online find specifications for this engine. new machine make about eighty psi Sixty psi is generally agreed to be acceptable. done a dry compression test results are we've got eighty psi and its been holding eighty psi for five minutes now. wet test is eighty psi. going under. take a look main seal end of crankshaft looks nice and dry not losing crankcase oil. Oil residue around the drain plug. either drain plug's weeping or it's spillage from above. just as likely. three eights square drive, fill crankcase with fresh oil clean up the surface where plug seats, nice and clean can't get dirt into your crankcase. not to overfill crankcase. problems you can get is too high base pressure engine's not breathing properly so it'll start misbehaving next look at your air cleaner. push on this spot releases lid. Pop the cover low density foam you can just replicate. similar piece of foam and cut a new one. garden debris picked up in top vacuum real quick, blow real quick ready to reuse. air intake screen keep this free of debris. leaves and grass clippings often here and travels through body into filter housing pop the housing and it's held by two screws one on either side of the carburetor intake. got screws out need to take lid off it falls away. intake system looks like. From this fan under grate picks up through this tube inserted here. general clean up springs and things have garden debris. governor mechanism here. breather tube try keep clean be certain to reconnect. no adjustment here. only adjustment is bend this metal tang, the governor spring is controlled by and that will speed up my high end. governor spring and this metal tang anchor point. Stretch the spring further to speed it up or compress the spring to slow it down. burning too rich add bit of speed to the top end..bent it tiny bit. want to clean that up, especially the breather. separate section cut in the sponge for breather see light coming through it's clear. take a rag. nice thick rubber gasket preserve that nice seal here on this aluminium deck. Tuck the pick-up into this here, line up breather. put screws back in. best reason keep machine clean these fins are cooling surface area air cooled depends on fins to provide larger surface area to exchange heat with air outside. pack that with lawn clippings going to become insulated and not do the heat exchange it needs operate efficiently. put in spark-plug after quick check. you may want to change your sparkplugs. cheap sometimes have a no-start could be a dead plug. such a common problem still have a no-startnot a bad idea to get a second new plug and make sure just tried isn't also dead.be prepared for smoke first couple minutes if wet compression test. little smoky at start up and might take a couple of pulls harder to ignite oil but it'll start and it'll burn off. guys will tell you to leave the sparkplug out and put a rag covering the hole but I respectfully disagree. all my internal combustion engines have the sparkplug stored in them. spring tune-up you're ready to go. fresh fuel pull the cord and it should start right up for you. My philosophy on almost any machine is: if it didn't quit on you while it was running -- if you shut it down, then it will run again. But if it quit on you while it was running, well... you could be in for a world of pain. run the machine for an hour after tune up. It's starting to whiten. it's obviously hotter this side. Either the tune-up or the raising of the operating speed has leaned out the mixture enough that we're starting to get a nice clean burn.