Fried my saw? But what's this yellow stuff?

Went to do some cutting today, and first pull told me it was toasted. Failed the drop test.




So, pulled the muffler, which fought like crazy, and found some weird yellow powder caked in the exhaust port. It FILLED the port completely. I picked most of it out with a screwdriver, and this is what it looks like:








The history is this:

This is a John Deere/Efco CS-52. I got it from an AS member (a couple of years ago) who modded (gutted) the muffler. It's been a champ so far. A few weeks ago, I changed the spark plug and cleaned the air filter after some heavy use. Spark plug looked good - nice light brown, evenly colored.

I found the muffler nuts had some loose, and the front half of the muffler had been rattling around, apparently for quite a while. I put it back together, using some star washers to hold it together better. The metal around one bolt had fatigued and cracked, opening up the hole a bit, so the wide star washer I used closed that up.

I've run about a tank and a half since then with no apparent problems. Last use was about a week ago. Went to use it today, and no joy.

When I pulled it apart, I found the back half of the muffler had also fatigued and broken:





This was hidden by a backing plate inside the muffler, so I didn't see it when I fixed the loose front half:






So, clearly I've had exhaust conditions for which the saw was not tuned, to say the least. (Where's the 'stupid' smiley here?)

I had expected to find smeared rings, but no, they just look collapsed. I see no smearing at all:





So, obvisouly I need to tear it down and rebuild it, but what in the world is this yellow stuff, and how did it get caked in the exhaust port? And what, exactly, did I do wrong?

High sulfur fuel? Organic bug guts? B-vitamins in the gas? Yellow fever?

Were you cutting yellow colored wood, like Hedge? maybe your air filter failed and it sucked a bunch of wood dust ??? I really have no idea, just a stupid thought???........

where was the saw stored at?

the yellow stuff wasn't there when you parked the saw.

bug poop???

Looks like a classic case of Suckback to me.

Classic case of using too much uranium in the fuel mix resulting in yellow cake in the exhaust, textbook.

That stuff almost looks like some sort of chemical or pigment.

Alright, cut the clowning guys, this is serious! A saw is lying here mortally injured!! Hey, it may not be a Stihl or a Husky, but it's still a SAW! And take your hat off! Ain't you got no respect??


Anyway, no sawdust. It seems to be more like packed sulfur, only it's not as bright yellow. I'm pretty sure it's not organic. Looks more something in the mineral family.

Saw was stored in the garage, and it's got plenty of room for critters to get in, but I don't think this is bug stuff. I do have plenty of mud wasps, but this is not their doing.

TreeCo said:

Mold from lack of use!

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Yo, Tree, it's been sitting all of a week!

TreeCo said:

Do you use Amsoil?

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Nope Stihl Ultra, 45:1. Non-ethanol gas, mostly.

COLD_IRON said:

That stuff almost looks like some sort of chemical or pigment.

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Yep. It was neatly packed in the port, and a bit fell into the muffler when I took it off. I should have taken a picture before I cleaned it out. I was anxious to get to the piston to see how bad things are.

BlueRidgeMark said:

Alright, cut the clowning guys, this is serious! A saw is lying here mortally injured!! Hey, it may not be a Stihl or a Husky, but it's still a SAW! And take your hat off! Ain't you got no respect??


Anyway, no sawdust. It seems to be more like packed sulfur, only it's not as bright yellow. I'm pretty sure it's not organic. Looks more something in the mineral family.

Saw was stored in the garage, and it's got plenty of room for critters to get in, but I don't think this is bug stuff. I do have plenty of mud wasps, but this is not their doing.

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id start doing some basic geology/chemistry on it. see if it burns/smolders and check with acids etc. i have seen yellow deposits on aluminum due to corrision, that would be alot though.

Dirt dobber nests? I assume your spark arrestor is gone?

spacemule said:

Dirt dobber nests? I assume your spark arrestor is gone?

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+1

I like the mud dauber theory but there may be some other causes.....

What kind of fuel were you using, pump gas, av gas, racing fuel, leaded, unleaded, additives?

It could be some kind of sulfer compound, chromium sulfate or an octane additive that was way too high concentration in the fuel. Does the substance dissolve in water or fuel? Might be way off as I mentioned I like the mud dauber theory. In any case that is just plain crazy and I have never seen anything like it in over 20 years of working on internal combustion engines.

Have you pulled the jug and piston yet? You may be able to clean it up, free up the ring, clean the groove and be cutting soon if there is no major damage.

If you look closely you can see some rust spots on the piston rings. My guess is the cylinder started to corrode is storage, and when you tried to start the saw the rings scraped that crap off the cylinder walls.

Bizarre! My first thought was sulfer too, Andy brings up a great point but what could leave corrosion that color? Old fuel varnish would sieze it or melt? I like the mud-dauber theory best. It can't be remnants of an old deteriorated filter because you'd think it'd be blackened from the exhaust, quite odd BRM, time for some scientific study, burn, melt, mix with fuel, mix with water, smell, texture, bake a cake?



Serge

djmercer1 said:

id start doing some basic geology/chemistry on it. see if it burns/smolders and check with acids etc. i have seen yellow deposits on aluminum due to corrision, that would be alot though.

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You forgot taste test JK :monkey:

Looks gross, never seen anything like that I'm laying my money on it having something to do with sulfur.

if you are going to run diesel, try to run lsd not hsd.


never seen a yellow dobber nest. it do looks like sulfur. question is how did it fill the port?

Do you and PlantBiologist share a BIL? Just wondering.:jawdrop: :jawdrop:

volks-man said:

never seen a yellow dobber nest. it do looks like sulfur. question is how did it fill the port?

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Yeah, the color is what makes me question the mud dauber. We sure have them around here, but all they make is plain old brown mud.

And yes, the spark arrester is gone, probably rattled out when the nuts were loose.

Here's a working theory:

Some mud daubers found something yellow to make mud out of, and started building in my exhaust port. (I have them in my garage often enough.) They got just as far as filling the port before I picked up the saw today.
When I pulled the cord, I sucked in some of the dirt, which grunged up the rings, thus the loss of compression.

Hmmmm. Well, whether heat related or mud daubers, it's gotta be torn down and rebuilt. Hope I didn't get any of that stuff in the lower end.


Maybe the mud turned yellow from the aluminum?


Just got back from taking a load of trash wood to the dump, so I'll try some experiments to see what I can learn about this junk.