Stihl BG-55 self ingesting parts...

[whitedog]

My wife took the blower over to the MIL's house to clean up some leaves...naturally it came home broken.

The only explanation was that the choke switch came loose. I suspect it was running AFTER the linkage broken inside the air filter. The choke is an orange two part linkage connected with a small round metal friction clip.

I ordered a new housing with new choke linkage on eBay for 12 bucks, I also ordered a couple extra of the metal friction clips.

Once it arrived, I reassembled the blower and gave the starter a tug...Ugh! it feels like something is hanging up inside the cylinder! So, I pulled the plug and removed the starter cover so I could spin the flywheel by hand.

Without the plug in, the flywheel is very tight and comes to a stop in a few different positions. Something is definitely binding. Shouldn't the flywheel spin easily? The worst case seems to have come true.

I'm sure my wife just kept running it after the link broke. Since it was hot and likely running, she probably hit the gas, opening up the throttle to the now liberated friction clip that is coincidentally just the right size to shoot through the throttle body and on into the intake...eventually lodging between the piston and one of the ports.

BTW - upon initial dis assembly, the friction clip was nowhere to be found.

So, my question is now: What's the easiest way to get the piston out for inspection?
TIA!

 

[KenJax Tree]

Honestly for $149 i would just buy a new one

 

[whitedog]

let's assume I want to spend $148 fixing it, how is the piston removed? or more importantly, shouldn't the flywheel spin free without any obstruction once the spark plug is pulled?

 

[KenJax Tree]

Not sure i never took one apart. Yes the flywheel should spin real easy without compression.

 

[jughead500]

Blown crank bearing.better check they like to ingest bearing cages.

 

[whitedog]

I think most engineers would agree, including a tiny metal fastener within the (unfiltered) air filter intake chamber that upon failure can be ingested into the motor is a moderate design failure. Perhaps it's more of a planned obsolescence feature. That friction fastener won't last forever. If I had a working BG-55 I would slap a dab of RTV silicone over that friction nut to keep it from moving far if it fails.

 

[whitedog]

Blown crank bearing.better check they like to ingest bearing cages.

I'm pretty sure it's the friction nut that fell off and got sucked into the motor. It was nowhere to be found in the air filter housing.

 

[whitedog]

Verified:
I removed the piston and the rings and side of the piston are pretty torn up.
Rings were cracked and the side of the piston scored. No big surprise, chunks of the friction nut were found in the crank case totally shredded, but one bit was positively recognizable as the nut.

Anyone think a ring & piston replacement might work? The upper cylinder feels perfect and smooth.

 

[jughead500]

Yeah that will work.I have a bg 55 in the same condition.ill have to look I may have been in your boat too.I assumed it was bearing cage that got mine too.

 

[whitedog]

I just received the new piston and rings, installed everything and fired it up. The blower idles great but as I squeeze the throttle, it dogs out. I release the throttle and it goes back to a nice idle again. Any ideas? I'm almost there!
It's always fun fixing these little engines.

I'm just hoping the intake ports didn't get clogged with part of that friction nut...you know, between the crank and the cylinder. The only thing that would be suspect might be the gasket between the cylinder and the crank case. I think it's symmetrical. If it's not, then I might be blocking the port with the gasket...not sure...

BTW - the spark arrestor is clean. I removed it entirely and the blower is very loud but revs full throttle...a little weak tho. Must be something on the carb side.

 

[ANewSawyer]

I seem to recall a recent thread where there was a blown cylinder and piston. Piston was trashed but the cylinder felt smooth at first touch. When the guy reexamined on the recommendation of the folks here, he found the cylinder damaged.

Also, have you done any adjustments on the carb?

You are probably used to this kind of work and all ready know all of this.