SteveSr
Addicted to ArboristSite
OP said that this was a "low hour" saw which sparked my question as to what might cause this much damage in such a short time.
Stihl 026 Leakage Test
- Thread starter 2tone
- Start date
Help Support Arborist Forum:
@SteveSr it could be many issues or a combination. I would guess that most cylinders are not mic'ed and they could not be true to size throughout the bore. Pistons can have defects and not be true to size either. A smallish piston in a larger than normal bore can cause the piston to rock and wear over time. The more it rocks the greater the piston slaps the top bore chamber.
We don't know how the chainsaw was stored between usage and where and for how long. Ethanol fuel has a short shelf life (3-6 weeks) and will start breaking down the oil added to the fuel over time. If the saw was stored with ethanol fuel it will attract moisture. So you can see where I'm heading... If the gas was not drained and fresh fuel and oil used for the next usage, then the saw was run with more moisture in the fuel, lack of lubricating oil and fuel that is old that is having a hard time producing combustion.
Have any of these conditions makes a impact on a piston going 14,000 RPM.
I'm sure there are other variables that we don't know of with the history of this chainsaw.
When the OP is finished rebuilding his 026 he'll have a great saw for years and have gained a valuable benefit doing it himself.
SteveSr
Addicted to ArboristSite
OP said t hat this was a "low hour" saw which sparked my question as to what might cause this much damage in such a short time.
2tone
ArboristSite Member
Case is split. The bearing stayed in the clutch half. Stuck my finger in the inter race and turned, It has one rough spot. I heated the case around the bearing with a heat gun and pressed it out using a carriage bolt and some washers and spacers.
Heated the flywheel half case with heat gun and tapped on the crankshaft, with nut on end, with a plastic shock hammer. The crank popped right out of the bearing. The flywheel bearing had light rough spots so reheated and pressed out with bolt.
The crankcase had light sludge spots but no other debris. I had already purchased the OEM seal kit with crankcase gasket, cylinder gasket and muffler gasket. So it looks like I need piston, rings, piston pin bearing, both crankcase bearings. In the meantime I need to clean up the upper cylinder. I need to research that.
One note and question: The bottom rod bearing on the crankshaft doesn't look replaceable and is not on the IPL. I pushed in and pulled out on it. No detectable movement. As previously discussed there is side to side slide movement. One other check I made is rocking the top of the rod towards both ends of the crankshaft. There is play there. Any thoughts?
Heated the flywheel half case with heat gun and tapped on the crankshaft, with nut on end, with a plastic shock hammer. The crank popped right out of the bearing. The flywheel bearing had light rough spots so reheated and pressed out with bolt.
The crankcase had light sludge spots but no other debris. I had already purchased the OEM seal kit with crankcase gasket, cylinder gasket and muffler gasket. So it looks like I need piston, rings, piston pin bearing, both crankcase bearings. In the meantime I need to clean up the upper cylinder. I need to research that.
One note and question: The bottom rod bearing on the crankshaft doesn't look replaceable and is not on the IPL. I pushed in and pulled out on it. No detectable movement. As previously discussed there is side to side slide movement. One other check I made is rocking the top of the rod towards both ends of the crankshaft. There is play there. Any thoughts?
drf255
BAD CAD
I forgot that part. As he bought it new, the low hour part is true (unlike most sale saws).
Honestly, no idea.
2tone
ArboristSite Member
Back working on Saw. Putting saw back together. On bearing installation - manual has flush side up up on clutch and open side up on ignition side. I'm curious as to why?
On further reading I'm calling the retainer side the flush side. The crankcase side is obvious in that the lip mates to the oil pump and the seal goes there.
On the ignition side the manual says place the open side to face the inside of the crankcase. So my question is - Why is the open side of ignition side facing the inside of the crankcase and the open side of the clutch side is facing out?
On further reading I'm calling the retainer side the flush side. The crankcase side is obvious in that the lip mates to the oil pump and the seal goes there.
On the ignition side the manual says place the open side to face the inside of the crankcase. So my question is - Why is the open side of ignition side facing the inside of the crankcase and the open side of the clutch side is facing out?
