What's wrong with this picture...

[Lakeside53]

I don't have a clue why something would get that covered in rust, unless you leave it sit outside all the time...


But Im in a boderline desert around here...

Oxygen (in water often) acting on iron causes rust. It doesn't have to be outside.

 

[rahtreelimbs]

The screw that holds the pivot pin for the needle!

 

[RiverRat2]

I cant concentrate Rotten Tree limbs

Well..........I could see the rust clogging up jets and the saw running lean as a result!!!

every time I scroll over anything you post my brain is................. running away with me!!!!!!!

What is not SST cost .10 dang it I cant look anymore!!!!!!

 

[Lakeside53]

from your pics, the only piece that has rusted is the head of the little screw that holds the metering arm down.

BINGO



Replace that plated POS with a stainless screw and the problem will be greatly reduced...

 

[somebum]

the part with 3 4 on it or the screw to hold the float together yes i have the carb off the 044 torn apart in front of me now it says a23 on it though oh or its the little cover in between the two

 

[rahtreelimbs]

every time I scroll over anything you post my brain is................. running away with me!!!!!!!

What is not SST cost .10 dang it I cant look anymore!!!!!!

Maybe I should get a free saw for my sig!!!:biggrinbounce2:

 

[somebum]

BINGO



Replace that plated POS with a stainless screw and the problem will be greatly reduced...

damn i lose mine is clean as a whistle had a little sawdust in it though

 

[Stihl_Learning]

Great thread Andy
Thank you

 

[Just Mow]

every time I scroll over anything you post my brain is................. running away with me!!!!!!!

What is not SST cost .10 dang it I cant look anymore!!!!!!

were you saying something, I keep having boobie flashing through my head.

 

[Lakeside53]

O.K., that's over...

I figure the alcohol in the gas absorbs water. It slowly attacks that screw particularly if it sits in the carb for months. Once the plating is gone, it's rapid rusting.

I see this more and more. Great for service (NOT) but it often clogs the carb really bad. I'm still not sure if I can save that L jet/check valve in that carb, and it's not replacable.

The cylinder cleaned up o.k.. amazing...


I'm replacing all my carb metering arm screws..

 

[Just Mow]

O.K., that's over...

I figure the alcohol in the gas absorbs water. It slowly attacks that screw particularly if it sits in the carb for months. Once the plating is gone, it's rapid rusting.

I see this more and more. Great for service (NOT) but it often clogs the carb really bad. I'm still not sure if I can save that L jet/check valve in that carb, and it's not replacable.

The cylinder cleaned up o.k.. amazing...


I'm replacing all my carb metering arm screws..

I STIHL say it was the rust fairy

 

[BobL]

I just saw this post and as a follow up, recalling some high school chemistry, if you heat rust in the presence of ally the following happens;

Rust (Fe203) + 2Al (metal) = 2Fe (metal) + Alumina (Al203)

This is a well known chemical reaction called the thermite reaction - you can fuse-join railway lines with it - ie a handfull of rust and Al powder. Any rust get's inside the cyclinder and sits on the piston will convert any nearby ally to a metallic iron coating mixed with a serious abrasive (Al203) - I guess thats what we're looking at.

 

[Lakeside53]

I just saw this post and as a follow up, recalling some high school chemistry, if you heat rust in the presence of ally the following happens;

Rust (Fe203) + 2Al (metal) = 2Fe (metal) + Alumina (Al203)

This is a well known chemical reaction called the thermite reaction - you can fuse-join railway lines with it - ie a handfull of rust and Al powder. Any rust get's inside the cyclinder and sits on the piston will convert any nearby ally to a metallic iron coating mixed with a serious abrasive (Al203) - I guess thats what we're looking at.

Great theory, and I remember doing that experiment in School, but the rust never made it to the piston - just blocked the carb and leaned out the mixture.

 

[KMB]

O.K., that's over...

I figure the alcohol in the gas absorbs water. It slowly attacks that screw particularly if it sits in the carb for months. Once the plating is gone, it's rapid rusting.

I see this more and more. Great for service (NOT) but it often clogs the carb really bad. I'm still not sure if I can save that L jet/check valve in that carb, and it's not replacable.

The cylinder cleaned up o.k.. amazing...


I'm replacing all my carb metering arm screws..

Does Stihl have the stainless screws available? Where else is an easy place to get them? And as already mentioned, great thread and info. Thank ya!

Kevin

 

[Jaxx]

Great post -- informative. Thanks Lake.

Rah's posts were distracting.... If you know what I mean.

 

[Lakeside53]

Does Stihl have the stainless screws available? Where else is an easy place to get them? And as already mentioned, great thread and info. Thank ya!

Kevin

Nope... I'll measure them, but they look like 6-32 screws to me.. Available at a real hardware store. I might make a list (I think there are only 2) of the screws in the common carbs.

 

[BobL]

Great theory, and I remember doing that experiment in School, but the rust never made it to the piston - just blocked the carb and leaned out the mixture.

OK - I agree that the leaning of the mixture was the major culprit but how can you be sure that small amounts of very fine rust didn't get to the piston?

 

[buzz sawyer]

Thanks Lakeside, great post!
I shuddered when I saw that piston! (I had actually narrowed it down to the screw or the suckback preventer about halfway through the second page. lol)

Could this be one reason they recommend not leaving a saw for extended periods with fuel in it? Maybe better to just run it empty when it will not be used for more than a week or so? Does this happen with saws other than Stihls? I haven't seen this on my Homies or the Mall.

 

[Lakeside53]

It's not a Stihl issue - it's a Walbro/Zama/Tillotson issue... and those carbs are used everywhere. One stupid plated steel part in the carb and the potential for rust exists.

Water in the gas is the real problem. Use fresh mix, no alcohol if possible, dump out your gas cans now and then, don't store it in a saw for more than 60 days etc etc.. If your saw dies and you suspect water in the gas, flush it out and clean out the carb - don't shove it to one side and get back to it months later.

This won't happen in every saw or area, but it sure does happen a lot out here, and more frequenjtly than in the past. The saw in question wasn't even three years old!

 

[Lakeside53]

OK - I agree that the leaning of the mixture was the major culprit but how can you be sure that small amounts of very fine rust didn't get to the piston?

I can't, but I see a a lot of piston failures, and this is was just like all the other abused "lean" burn outs. The user was obviously inept - it doesn't melt down like that in a minute...