twotalltree
New Member
Newbe here...
Looks like I missed something with my diagnosis on my Stihl 029 Super. I purchased this saw 20 years ago and used it every firewood season since then. I am a closet logger you know. I have three other Stihl saws but this one is my go-to saw.
Last weekend I was bucking some downed trees, took a 4 hour break and when I tried to restart the saw it would not start. I did all of the basic troubleshooting steps and in short the fuel and ignition were OK. Maybe I flooded it when I splashed some fuel in the spark plug port. I could not get it to even pop by bypassing the carb. It had a small blue spark too. I looked at the piston and rings thru the exhaust port and they looked fine, ie, no scoring or burnt colors.
This is where I drank-the-cool aid. Because the saw is like 20 years old I suspected poor compression so I bought a $30 compression tester at HF. You know the kind with a 6 or 8" hose and has the schrader valve near in the gauge (not the spark plug port) resulting in an incorrect reading of like 40psi. Eureka I said, it's needs a new piston and/or rings. I tore down the saw (thank you all for great insights as to disassembly and education) and on closer inspection of the cylinder, piston, seals, bearings, races and rings they look almost in new condition. I can still see the original tooling (witness) marks on the piston and the rings appeared good too. I even put them under a microscope. As an after-thought, I compression tested two other never used saws (MS290, MS362) and got the same 40psi or so measurements. Looks like I have a "project saw" for the summer. The rest is history...
I am (no pun) stumped because what else is left but a chain saw all torn down?
So, because the engine is torn down I might as well replace the rings and seals, reassemble and see if it will start; stuck rings maybe? Vacuum leak? Poor spark?
Any ideas would be very appreciated.
Steve
Looks like I missed something with my diagnosis on my Stihl 029 Super. I purchased this saw 20 years ago and used it every firewood season since then. I am a closet logger you know. I have three other Stihl saws but this one is my go-to saw.
Last weekend I was bucking some downed trees, took a 4 hour break and when I tried to restart the saw it would not start. I did all of the basic troubleshooting steps and in short the fuel and ignition were OK. Maybe I flooded it when I splashed some fuel in the spark plug port. I could not get it to even pop by bypassing the carb. It had a small blue spark too. I looked at the piston and rings thru the exhaust port and they looked fine, ie, no scoring or burnt colors.
This is where I drank-the-cool aid. Because the saw is like 20 years old I suspected poor compression so I bought a $30 compression tester at HF. You know the kind with a 6 or 8" hose and has the schrader valve near in the gauge (not the spark plug port) resulting in an incorrect reading of like 40psi. Eureka I said, it's needs a new piston and/or rings. I tore down the saw (thank you all for great insights as to disassembly and education) and on closer inspection of the cylinder, piston, seals, bearings, races and rings they look almost in new condition. I can still see the original tooling (witness) marks on the piston and the rings appeared good too. I even put them under a microscope. As an after-thought, I compression tested two other never used saws (MS290, MS362) and got the same 40psi or so measurements. Looks like I have a "project saw" for the summer. The rest is history...
I am (no pun) stumped because what else is left but a chain saw all torn down?
So, because the engine is torn down I might as well replace the rings and seals, reassemble and see if it will start; stuck rings maybe? Vacuum leak? Poor spark?
Any ideas would be very appreciated.
Steve
