028AV super question

[sawjo]

I am just starting to dabble with saws and have successfully torn down and rebuilt about 1/2 dozen smaller saws and a couple of Homelite super XL's. I am facing my first Stihl saw and need some newbie advice. My buudy gave me this saw and said it was locked by straight gas. I dove into it Sunday and after removing the starter cover and muffler discovered that it was'nt siezed. It turns in both directions back and forth but will not make the cycle. Its funny, I was working it back and forth and it started to turn all the way - I even had spinning with a drill/socket to check spark. Then I removed the flywheel and now its hitting something with a metal clang sound - not good. Something is loose or broken. Any tricks to getting the jug off? Should I remove handle/carb/boot first? Do I use a long handle Torx driver to remove jug? And finally, I am confident that I could replace piston/pin - is it worth it?
TIA.

 

[rmihalek]

Maybe it seized but also broke the connecting rod in the process? When you spin the flywheel, can you see (or hear) the piston moving up and down? If the con rod is broken, the crankcase may be beyond repair.

To remove the cylinder, you'll need a long handle T27 Torx driver. You should remove the muffler, carb, carb boot and spark plug/wire before attempting to get cylinder off.

To get the throttle linkage off the carb, just squeeze the throttle trigger wide open, reach in and hold the outside throttle plate still then let go of the throttle. The throttle rod will loosen a bit and then pop off the throttle plate. The impulse line and fuel line then need to come off the carb. Carefully push the rubber boot through the housing once the carb parts are all off.

Oh yeah, clean all the saw dust from around the cylinder base so when you pull the cylinder off, you don't have all that crap falling into your crankcase.

 

[sawjo]

Thanks Bob,
I can see the piston going up and down and its in good shape so I believe it hasn't been lean seized. It is clanking and stopping on something at or near BDC though. I will remove jug and futher investigate. Is it worth repairing if I do the job myself? I have never dealt with Stihl for parts and availablity and I know there is not much available on the Web.

 

[sawjo]

Well I got to the root of the problem last night. I pulled the jug and noticed a small (1/2") long piece of the main drive bearing outer race ( I can see the broken bearing) floating around in there. I am wondering if it broke while saw was shut down because there is no damage to the other parts. Can this bearing be replaced by itself or is the crank/rod/bearings a one piece assembly? Any tips?

 

[rmihalek]

I can't help with with disassembling the bottom end since I've yet to do this with my saw. I'd bet that you can split the cases, pull the crank out and replace the bearings, but you may want to try this: most broken 028s on eBay are seized. I bet you can get a decent saw that had straight gas run thru it, swap over your piston/cylinder and you'd be good to go.

 

[TonyM]

Went through the same thing. Had an 028 Super with bad crank bearings. Picked up an 028 Woodboss crankcase on eBay for total of $25 and put it back together. The Woodboss crankcases work, but have a minor difference in the chain tensioner area. Either make sure the plastic sprocket/oiler cover and tensioner is there if you buy a used Woodboss, or plain on cutting the plastic cover from the Super to fit and buying a tensioner screw. The 028 had a three screw recoil cover at one point that later switched to four screws. Just some things to watch for.