James Sawyer
ArboristSite Operative
I'm finally get around to rebuilding one of my dads old 461. What method do you use to block off the intake on a short block for leak testing without the tank assemble on.
Leak testing a short block Stihl... Intake block suggestions.
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Best is to use a proper block off plate if possible, alternatively some inner tube between the carb and manifold, but this can be a leak point that won’t be tested with the second method.
I carve plugs out of closed-cell foam.
https://www.arboristsite.com/threads/show-us-your-pressure-vac-tester-and-block-off-plates.368677/
https://www.arboristsite.com/threads/show-us-your-pressure-vac-tester-and-block-off-plates.368677/
You really need about $400 worth of mighty vacs and block off plates to test a 461. You won’t have any $ left to buy saw parts, but these fellas will have you a nice airtight 461.
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I have made tools out of old junk carbs and silicon. You can put a nipple on it to for testing there as well.
James Sawyer
ArboristSite Operative
I do have intake block-off plates for cylinders that have carburetor mounting studs...but to use the one's I have... I'd have to install the fuel tank assemble back on this MS461. The intake boot attaches to the cylinder (hose clamp) and then fit inside a bore in the fuel tank assemble. The fuel tank assemble has the carburetor mounting studs that holds the carburetor against the boot to make the seal. Surely someone has leak test a newer Stihl short block like this after a rebuild without installing the fuel tank. I've been looking on-line figured someone sold an intake boot plug for leak testing these saws, so far haven't found one. This is an old saw my dad had that had lot of hours on it. He said the saw was completely worn out and a bought new saw. It's been sitting in my barn for few years now. I started tearing the saw down for a rebuild...looks like the PTO seal may have been the problem. I wanted to leak test it, get the timing numbers and squish before tearing it completely down. I just want to know what failed on it before rebuilding it and a leak test tells a lot.
I'd just go ahead and replace anything made of rubber on it, then vac test once you have it back together.
Stuff a rubber plug in the intake and clamp it.
Maybe a pic of what you got would help. It sure sounds like you just shove a foam plug into the rubber intake boot.
The best test is with the tank on as that is also a sealing point.
