041 Problem and Theory

[lawless154]

Last fall while cutting wood, my 041 sounded like it ran out of gas and died. I filled it back up and it wouldn't run. I could start it with the choke on and it would idle, but take the choke off and it would die pretty quick. Give it a little gas and it would bog down and die. I got home and tried getting it to run, but got the same results. Eventually, I couldn't even get it to start with the choke closed. I took the carb off, cleaned it, and replaced all of the wear parts on it. Still nothing. I put some mix straight into the carb and it would run for a second or two and then when that ran out, it would die.

At this point I figure I've got a fuel supply issue, so I replaced the gas line, filter, and the impulse line. I get air coming through the impulse line when I crank it by hand, but not sure if it's enough to flex the diaphragm. I dig down deeper and take off the carb intake flange and deflecting plate and the gasket between the carb deflecting plate and the cylinder is deformed inwards towards the intake. My current theory is that that gasket failed while cutting wood and developed an air leak. After running it with the choke closed, it got worse until there was not enough vacuum to pull fuel through the supply line. I'm going to get a new gasket kit and reassemble it to see what happens.

Does this theory sound reasonable? Also, when replacing the gaskets around the carb, do you guys usually grease or oil the gaskets, or put them in dry? If nothing else, it's been a good learning experience for how a chainsaw gets fuel from the tank to the cylinder. I appreciate any thoughts on this.

 

[hotshot]

You're correct, running lean with an air leak, and that's not uncommon for those intake gaskets to suck in like that. I put Motoseal on my fingers tips and then coat the intake gaskets on the 041 before I set them on. Only the 041, and the P3400 Poulan series saws do I coat the intake gaskets like that. Also need to use blue/medium Loctite on the intake bolts' threads.

There are literally a dozen places for those old 041s to have air leaks, and 8-10# air pressure testing with a bottle of kids soap bubbles or Windex will show them all, as you covered three of them!

1) PTO or Right Side Crank Seal
2) Oiler Worm Gear to shaft Seal -OR- Bar oiler gear cover seal
3) Starter/Magneto or Left Side Crank seal
4) Cylinder Jug Base to Crankcase (CC) & the Studs x4
5) Crankcase, Case halves Punch Pins (x2), & the CC Side Halves Case Gasket
Also "bubble check" the oil filler hole (Double checks the internal crankcase gasket integrity when the oil tank is a common casting). Pressure test only.
6) Impulse Line Elbow Fitting at CC & the Impulse Hose
7) #1 Lower Intake Cylinder/Shield Gasket
8) #2 Lower Intake Shield/Manifold Gasket
9) #1 Upper Intake Manifold Block Gasket
10) Bar Oiler Rate Adjuster Screw O-Ring (at rear)
11) Bar Oiler Drive Gear Front Grommet
12) Bar Oiler gear shaft brass plug (back of case)

 

[lawless154]

Thanks for the info. I'm going to start with the intake gaskets and go from there. Hopefully this problem is as easy as that and I'll have my favorite old saw back up and running again.