Chainsaw Repair
Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Stihl => Topic started by: sean.o.farrell.52 on January 06, 2017, 11:06:12 pm
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I was given an old stihl 056AV by my dad last year to take care of some larger wood around my property. It has run great the few times I have used it. The past month and a half I have pulled it out about 3 times to cut firwood. I've ran it enough to cut about 6 rounds each time... maybe 5-10 minutes total run time. Then emptied the gas and put it away.
Last time it ran, it ran fine and I turned it off per usual, it did not die on my. I went to cut some wood a few days ago and it wouldn't start. Same gas I've been using, and the gas starts my other saws fine.
I pulled the plug and tested it (rested it on the head and pulled the starter) I was getting what looks to me like a strong blue spark.
The top of the cylinder looked wet, so I thought maybe I flooded it, so I let it sit with the plug out for a while, then put it back and had the same result.
I have also cleaned the air filter, didn't help.
I pulled with the air filter off and I am getting some gas running out the back of the carb. I'm not sure if that is normal.
Also, after I pull a several times, I hear a sort whine that sounds almost like a pully with a bad bearing spinning down... but nothing is spinning on the saw at that time...
I bought a new spark plug, didn't help
It has been freezing here lately, so I brought the saw in and warmed it up.over night and it still.didnt start.
I don't know what to look at next. Any advice would be really helpful.
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Well, I just pulled the top cover off to get a better view at the piston, cleaned it (the saw, not the piston) a bit and reassembled it. Spritzed it with starting fluid and it started right up. I goosed the throttle a few times and it seemed to be running on gas before I let off and idled down and died. It's too late to be running saws, but I'll investigate more tomorrow.
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Put it away when warm/hot, now won't start cold, wet plug, fuel backing up in the carb inlet. You have a good spark and fuel getting to the plug. Classic signs of little or no compression or air leak. Scored piston?? Strange it should run with fuel straight in the bore though and once burnt off it stalls- especially as you have already stated there's fuel getting it there. You pulled the exhaust- what condition was the piston in??
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You can pull the muffler and then turn it over while looking at the piston to make sure it is ok. But I suspect that it is the carb not delivering any fuel.
You can tell real easy. Pull the plug first to see if it is dry or wet. If the plug is dry then take a little 2 cycle mix and put it direct into the carb throat while holding the throttle wide open. Then while holding the throttle wide open pull the rope until it tries to fire. You should get it to pop off. If not then pull the plug again and see if it is wet.
What this will tell you is that the spark is good at the plug and that the compression is good also. It will also tell you that there is enough pressure in the crankcase to move fuel from the crank case up through the transfer ports into the combustion chamber. Then you will have to find out why the carb is not working. It could be the carb itself or a leak in a intake or a impulse to the carb. Let us know what you find.
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Thanks for the replies, I have used the saw twice since I posted, and he has been hard to start cold, but starts just fine after I warm it up. I'll check out what you guys recommended and see what I can find
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Welp.... Guess I'll start the teardown...(https://uploads.tapatalk-cdn.com/20170213/c223f071a88e5ee4c4ba91cc9dedda90.jpg)
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Welp.... Guess I'll start the teardown...(https://uploads.tapatalk-cdn.com/20170213/c223f071a88e5ee4c4ba91cc9dedda90.jpg)
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Oh my gosh Sean. Was that saw straight gassed? You need to find out why the piston scored so bad so you do not repeat it.
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Yeah, I'm pretty sure that's what happened. I must have filled it out of the wrong can. I'm going to try to clean the cylinder and see if I need a new one. I'll pressure test it once I get this fixed and see if I need any new seals.
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Or maybe I'll do the gaskets and seals all at once...
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Yep accidents sometimes happen. It is a shame but can be fixed.
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Well, when I pulled the piston it was pretty mashed up. The cylinder looked bad, but I was able to dissolve most of the aluminum off with acid. Then I honed it and got it pretty smooth.
I ordered a new piston, but I wasn't sure it would work, since I had no specs but diameter.
I put it back together today and it kicked over first pull, then started first pull when I turned the choke choke off. I let it idle for a minute and the idle seemed really smooth. It has never started so cleanly since I owned the saw. I think i should pressure test the crank case before I run it too long though.
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Yes by all means test that crankcase pressure.