Vac/pressure testing saws

[stilh036prohog]

Just got my mityvac 8500 today. First of I have never done it before. Should had brought this year's ago but I just winged it. Couple of questions. Do you do the vac or pressure test first? I got some 1/8 thick silicon rubber to block the exh and carb. Just looking for tips. First saw is a 026. And the evapo-rust is the bees knee.

 

[stilh036prohog]

Just open the case and its broken already. Sucks

 

[LonestarStihl]

Well that was a quick thread...

 

[homemade]

I don’t think it really matters if you do a vac or press test first. I do a vac first and if it leaks hen press to find the leak. Remember, you only need 5lbs or so to find a leak. Once you start getting past 10-15 the lip seals won’t hold.

 

[hotshot]

Remember, you only need 5lbs or so to find a leak. Once you start getting past 10-15 the lip seals won’t hold.

Well I’d rectum sore!

10-15 of what?

A standard radial seal is rated at 7 # pos & 15”Hg neg...at ambient temperature.

 

[cedarhollow]

what do you use evaporust for. i tried it a couple years ago on a pto rototiller
it didn't do anything. but then again if the county fair gave out rust awards i'd have blue ribbon winners

 

[homemade]

10-15 lbs Of pressure on the case. That will blow past the oil seals making you think the seals are bad but instead it’s just over pressure.

 

[stilh036prohog]

what do you use evaporust for. i tried it a couple years ago on a pto rototiller
it didn't do anything. but then again if the county fair gave out rust awards i'd have blue ribbon winners

I soak hand tools in overnight. They came out looking new

 

[stihl86]

Vac first. Then pressure. (.5 bar / 7.5 psi) Rock the crank slightly when doing the vac test.

 

[hotshot]

I soak hand tools in overnight. They came out looking new

Good on muffs too!

 

[stilh036prohog]

Evapo-rust is good stuff. Now to get a new mityvac. I was really excited to do my first test. O well my spring came today for the 281xp I been waiting for three weeks. I want to put some wood this weekend. My biggest saw to date. Damn cad.

 

[Vintage Engine Repairs]

Good on muffs too!

View attachment 774773 View attachment 774774

I needed to know this! What about removing the carbon

 

[pioneerguy600]

I needed to know this! What about removing the carbon

Do it all at once, bead blast!

 

[Vintage Engine Repairs]

Do it all at once, bead blast!

I’d love a bead blaster but the compressor noise and space restrict me from getting one!

 

[pioneerguy600]

Paint stripper will remove carbon if one does not have to worry about paint, Tal Strip, paint remover for aluminum surfaces removes carbon quickly, I have used it for years when doing valve jobs and engine rebuilds.

 

[Vintage Engine Repairs]

Paint stripper will remove carbon if one does not have to worry about paint, Tal Strip, paint remover for aluminum surfaces removes carbon quickly, I have used it for years when doing valve jobs and engine rebuilds.

Amazing i’ll have a look online for some now! I was going to get the dremel and wire wheel out

 

[TheTone]

This may not be the most efficient method, but it works for me. Turn the cylinder upside down with a spark plug in it. fill the combustion chamber with brake fluid, just above the level of the carbon buildup. Let sit 3 days or more. Use a wire broom shaped brush on a Dremel and go over the combustion chamber. Comes off nicely. For carbon on a piston crown, I turn it in a circular motion on 220 grit on a flat surface. For carbon in the exhaust port, I go straight to a carbide bit and grind it all off. Then I do the flapper method with progressively finer sandpaper to end up with a polished port which will resist carbon buildup in the future.

 

[stilh036prohog]

Slow down on that grinding wheel. Aluminum is different than magnesium. If you right y understand

.

 

[stilh036prohog]

Slow down on that grinding wheel. Aluminum is different than magnesium. If you right y understand

.

Tig

 

[TheTone]

Slow down on that grinding wheel. Aluminum is different than magnesium. If you right y understand.

I'm thinking you mean that at high speed aluminum will stick to the grinder and clog it up. All I really do is grind off the carbon and get into the metal as little as possible. I used to use the sanding flap method on the carbon, but it took forever. Once the carbon is off, the flap polishing goes fairly quickly.