Stihl 076 gas leak question

[rayrayyj]

Hi all, got a nice 076 I mill with, she runs great (full rebuild), but when left sitting pukes gas all over the floor. It looks like the gas comes out of the carb...

The tank is self contained, no gasket, and doesn't leak.

New fuel lines, all of them.

New carb, I rebuilt the old one, figured the needle was sticking open, still leaked, so got new.

Kind of at a loss as to why the gas leak....

Could it be as simple as the gas cap?? These saws don't have tank vents like newer ones, so the caps vent. Could my gas cap be old and non-functioning causing a vacuum or pressure in a sense and pushing the gas out into the carb as a leak??

Pukes out to the half tank level.

Thanks in advance for any ideas, going crazy here!!!

 

[alexcagle]

What do you mean " the tank is self contained, no gasket, and doesn't leak?"
*
Is it a remote tank on a mill?

 

[Cease232]

What do you mean " the tank is self contained, no gasket, and doesn't leak?"
*
Is it a remote tank on a mill?

The tank on an 076 is one piece, no seam.

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[alexcagle]

Did you pressure test the tank?
You can use your thumb to block off the cap vent.
How long has it been doing this?
That is strange.

 

[rayrayyj]

I haven't pressure tested the tank, but no leaks on the tank, it's out of the carb, I'll check to be sure.

And yeah, odd, no clue why/how it leaks to the halfway point...I'm at a loss.

Going to mess around with it now.

 

[1Alpha1]

It's been my experience that some of the greatest mysteries ever encountered, originate from chainsaws and other various pieces of outdoor power equipment.

Who would have thunk?

 

[tomdcoker]

The tank on an 076 is one piece, no seam.

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The tank has a seam. Look at the line between the fuel cap and the fuel line. The screws that hold it together are on the right side in the picture. Yje tank vent is in the cap. It is possible that it is not functioning and pressure builds up in the tank. Tom

 

[Cease232]

The tank has a seam. Look at the line between the fuel cap and the fuel line. The screws that hold it together are on the right side in the picture. Yje tank vent is in the cap. It is possible that it is not functioning and pressure builds up in the tank. Tom

Not sure what screws your talking about Tom. There is a seam yes but it's welded.



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[alexcagle]

It is a vestige of the earlier tank design.
It is cast, but made to look like a seam for some reason.
An 032 I used to have was same way, but leaked at that seam strangely.
It was detectable though under pressure with soapy water.

 

[Cease232]

Seems like a leak at the seam would actually help in this situation.


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[alexcagle]

 

[tomdcoker]

It is a vestige of the earlier tank design.
It is cast, but made to look like a seam for some reason.
An 032 I used to have was same way, but leaked at that seam strangely.
It was detectable though under pressure with soapy water.

OK. I have had 031 saws that were cast in two halves and is made on the same style. I looked on an IPL and it did not show it to be a two piece. Should have noticed it, but due to old age ( best excuse I have got) I missed it Tom

 

[s sidewall]

Sounds like fuel cap not venting, pressure test and see if the cap releases pressure.

Steve

 

[rayrayyj]

Ok....got it figured out, should have pressure tested first as suggested.

Took the tank off, cleaned it up, filled with gas, and hooked up carb to see which would leak. Turns out I have a tiny pin hole in the tank, took a bit to find it, but leaving it for a few minutes sitting on a blue paper towel showed it was the tank.

Crazy how the location of the leak allowed gas to drop as if coming from the carb, guess by checking the saw while on it's side allowed gas to travel right along the carb body.

Another lesson....

 

[Bwildered]

The tank is two piece, the halves are glued together with some sort of super dooper adhesive.
Stanks

 

[alexcagle]

The tank is two piece, the halves are glued together with some sort of super dooper adhesive.
Stanks

*
Area 51 technology.....lol
They must use the same stuff to glue car hinges on to support 80lb doors.

 

[Bwildered]

*
Area 51 technology.....lol
They must use the same stuff to glue car hinges on to support 80lb doors.

I'd almost say it's a very hot melt plastic they use, because mine only leaked after having a weld repair done.
Stankski

 

[rayrayyj]

Used pro-poxy 20 (from amazon) to seal the tank, great stuff, works great....if anyone needs to fix a tank.