Barn Find Stihl 031 AV

[Cliff R]

Went to look at a car and some car parts and look what followed me home.

Never ran one of these but it looked like it might be a good one. Has been sitting in a machinery shed for at least 25 years if not longer.

All I could find wrong with it was the carb diaphram was torn. Has good compression (155psi) and good spark. We'll find out how it works in a few days......

 

[Ikeholt]

Wow, nice job cleaning that up. I have one about like that, has torque, fun to run now and then.

 

[Mad Professor]

Nice clean up!

 

[Cliff R]

Thanks. I have zero experience with the 031AV and haven't had one brought to the shop in all the years I've been working on them.

I pulled three 038's from a dumpster behind a rental shop decades ago and made one good saw out of them. Although I didn't keep it that saw was built like a tank.and ran well. I don't remember it being overly impressive for top end power but pulled pretty well in the mid-range.

I like resurrecting old saws from the brink of extinction and enjoy running them once in a while, but I'm pretty much all "business" when it comes to firewood, and we cut for three boilers here so no time is wasted on any outing. I'll load up at least 5-6 saws ready to cut, and run all of them till empty or I hit something where they quit cutting well. Then we load and haul wasting not one second all day long messing around with equipment, or sharpening chains, refueling, etc, etc.......

 

[saxman]

My great uncle bought one new in 1975 or 1976. I ran that saw for many years until it was stolen from my garage. They are a very solid saw, a little heavy for their power but smooth to run.


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[Cliff R]

I wasn't really expecting high HP to weight from the 031AV but for sure it's fun to run older saws once in a while. I ended up stripping this one all the way down just to get it cleaned up effectively, but did not remove the flywheel or split the case. It's very well built and super easy to work on. The "drop in" fuel line and plastic fitting is pretty cool, and a lot better than fishing a line thru a hole in the tank. Remarkably all the rubber parts are in great shape aside from the torn pump diaphragm. Doesn't even need a new pull rope. Hopefully it will be up and running tomorrow when the carb kit shows up..........

 

[HarleyT]

Take apart the fuel filter and see if the foam insert is still there. After @ 30-40 years, that foam will crumble and the particles will clog your carb up.

 

[Cliff R]

I removed the filter from the hose and blew it out. Didn't notice any insert in it, just a steel mesh screen....tks....

 

[HarleyT]

Yeah, it is just a barrel shaped piece of foam, the mesh screen, and the lead weight. Stihl just sells a whole new filter assy.

 

[Cliff R]

I went back and removed the filter and the rubber end plug and the foam insert was still in there. Although intact I didn't risk putting it back in place. Thanks for the tip.....Cliff

 

[HarleyT]

Yeah, it is amazing that most of the 031's running these days have the original fuel line, the foam in the filter doesn't start breaking up until 30 years old.

 

[Cliff R]

Carb kit showed up today, that went well, but this saw will not fire at all. Has spark, fuel, compression, nothing, not even a "pop". Had the carb back off twice, even replaced the spark plug, nothing. I walked away from it late last night, will mess with it some more today. Not sure at this point what's going on? Although the spark is strong it seems like it isn't doing anything at low cranking speeds, but fine with the plug out and I'm spinning it pretty fast. Hopefully something simple that I missed someplace.......

 

[HarleyT]

Carb kit showed up today, that went well, but this saw will not fire at all. Has spark, fuel, compression, nothing, not even a "pop". Had the carb back off twice, even replaced the spark plug, nothing. I walked away from it late last night, will mess with it some more today. Not sure at this point what's going on? Although the spark is strong it seems like it isn't doing anything at low cranking speeds, but fine with the plug out and I'm spinning it pretty fast. Hopefully something simple that I missed someplace.......

The spark can easily fool you on these models. It may appear strong. I would suggest you clean and adjust the points, set them @ .016. There are usually two windows on the flywheel.

 

[Cliff R]

That's where I'll go next, pretty much have ruled out fuel. It woln't even "pop" if I introduce a little fuel directly into the intake. The plug is also wet when removed, so off comes the flywheel cover when I get a little time to look at it again.....

 

[HarleyT]

The two plastic windows are removed by backing the center screws of a tad, and the white plugs will pull out.

 

[HarleyT]

the cam is on the flywheel, so you need it to adjust it with the flywheel on.

 

[Cliff R]

Cool, will do....tks. for the pics and info...

 

[HarleyT]

Cool, will do....tks. for the pics and info...

No problem cuz.

 

[Cliff R]

The points weren't far out of adjustment so I fear other issues. I cleaned them up a bit and set to .016".

Spinning the engine with my drill it's firing nicely once moving pretty fast, but inconsistent at very low speeds and often not firing at all. Not sure what's up with that?........

 

[HarleyT]

Some of the guys here had found a good cheap replacement for the condenser, but the last ones I just switched over to a electronic trigger module. If you get the incorrect aftermarket one, you will have to alter the timing, so I just use the ones I find on junk 011s, it has the same STIHL module.
Here is the blowup of the 031, and also the list of saws that share the same trigger unit. The 032 uses a different one.