I have a few questions for some of the mechanical gurus. In my experience, most engine and small equipment issues that homeowners have come down to simple things like improper fuel, dirty carburetor/blockage, simple mechanics vs. complicated end fixes. I found a Husqvarna 350 (yea yea, homeowner saw. But for here in Wyoming, I think it's the perfect saw for Lodgepole cutting) that looks brand new. One owner. He mentioned that it needed crank seals because when he goes to full throttle, it dies. I inquired further about his comments and he wrote: "I had it into a mechanic because it would kill after throttling it up. He rebuilt the carb, but that did not fix it. I have owned it for 20 years. Evidently, the crank seals get brittle and fail over time. This can cause the engine to run lean, causing it to run hot, leading to the wear on the pistons. The cost of the repair for me was not worth it. Crank seals are cheap, but not the labor. If you are mechanically competent and can replace the needed parts, this is a good deal." Looking at the saw, it's been replaced with a chinese replacement carburetor. To me, it's not getting fuel. Either the fuel line is cracked, the impulse line is cracked, or there is an obstruction in the carburetor, or improperly tuned. Thoughts? Second question on a 350, I recently have had an issue with the chain brake. It's as if the side cover has tilted outwards on the top and when you go to release the chain brake, it slides past without disengaging. You have to hold your hand on the cover at the top and then it grabs correctly. I cleaned everything and it still occurs. Is it possible the chain brake itself is the issue (maybe the plastic tabs have rounded over on the chain brake area) OR is the bar cover somehow bent? Thanks all!
Can you ask him if it was pressure tested? I'm not inclined enough to know what crank seal symptoms show them selves as. In my mind, air would be pulled in around the seal making the air/fuel mixture very lean and making the saw want to rev? Perhaps on the bottom side air can be pushed out the seals. Outside my normal wheel house. I did rebuild one of these a long time ago. If you can get it going, it is absolutely a great firewood saw. Mine used to outrun larger cc Stihl models my buddies had, much to our surprise. The one I have is an old one. 1998 model. Carburetor is fully adjustable and no prime bulb or dished piston. Longshot could be the tank vent...some of these have 'duckbills' some have 'white pills'. That condition would change with opening of fuel cap. It's always something I consider after being fooled on many a small engine by a gas cap that isn't allowing air in/fuel out.
When you open up the throttle, it creates a vacuum in the case. If the crank seals can't properly seal, that vacuum will suck air in from the seals. This air that did not flow through the carb will lean the saw out, eventually scoring(melting) the piston. Seals for this clamshell design do not look like the typical crank seals. They wrap around the entire bearing, as seen here: I love these saws. There are a few know problematic areas though. One is the screws that hold the riser base to the case. They come loose, allowing air to leak in (same deal as above. Any air leak is a problem). If you look at the bottom of the saw, kinda under the gas tank you can see them. Here's a vid showing what I mean. When I get a 350, I remove one at a time and put blue Loctite on them. EDIT: found a better vid, hopefully it starts about 5min in. It would be helpful if you removed the clutch cover and posted a pic of that brake band. Maybe we could see something you don't.
If the riser base screws are #1 #2 would be the muffler screws. They come loose, allowing hot exhaust gasses to melt the case. Either remove them and use Loctite, or mod a 346 muffler bracket to solve the issue. Most guys use the bracket. #3 can be the plastic clamp for the intake boot. Get yourself a metal clamp and replace the plastic one. Right here: Husqvarna 350/346 Repair Thread. is a great resource for working on them and where I pulled the pics from.
The Wood Wolverine Thank you Thank you, I had considered those as possible reasons for the leak. To me, keep things simple. I think some mechanics jump to extremes or odd reasons for a problem. More likely than not, it's something more basic. I have a 20 year old 350 and no concern that the crank seals have become brittle and suck air. Btw, did you go to Penn State? My dad, my sister and I all went. Originally from West Chester, PA.
I have the same style 350, no primer bulb and removed the limiters on the carb. This sounds like a homeowner selling it so I'm doubting he knows if it was pressure tested.
Just re-read your post, if you suspect fuel line, that is fairly easy to replace and can cause the issue you talk about. Fuel line can collapse and restrict flow. Definitely throw new lines in (and filter) before going full monte on the seals. AND check those riser base screws. If you find one seems a bit loose, this could be the source of the leak. Not a PSU alum.. born in Gettysburg and grew up just outside of there. "Happy" Valley is about 2 hours north of me, Philly is about 2 hours east.
Forgot about the clamp issue. Shop should have caught that one. Also...mine no longer has a brake band in it. I fixed it once and it 'exploded' again, then I had a shop fix it and it exploded again. So it was deleted. I suspect my clutch cover probably is the culprit but was never bothered to chase it further. My carb has/had no limiters. There are about 10 variants of this saw if you count the 353s. I have the first iteration. Looks like this.
A 350 is a decent saw. Leaky seals don’t normally allow enough air to kill it. If the fuel system components are working correctly the saw will rev to the screw settings for a half second and will then scream. That 350 likely has impulse issues, a torn boot, or needs a fuel filter/line and a carb or at least a rebuild kit. But seals and bearings are doable with simple tools and some wrenchability if that’s what it needs
With what you’re describing, the first thing I’d do is replace the fuel filter. No matter what it looks like.
