Sorry it i got the name wrong. Im would like to test a saw to see if its sucking in air somewhere. Could someone please walk me through it and show me a decent set up to use. Thank you
How to vacuum test a poulan strato saw
- Thread starter Welderman85
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Generally speaking, plug exhaust & intake with cut up inner tube between muffler & port / carb & intake (on strato's you have to plug the strato ports too which can be a PITA). Apply pressure / vac through impulse or a spark plug adapter to about 12psi/ just under 1 bar. Pressure should fluctuate slightly if you turn the motor over but shouldn't drop by more than about 20% over 30 seconds.
Mityvac testers have a good reputation. I'd recommend getting one that does both pressure & vacuum (& comes with all the extra bits for bleeding brakes etc as it costs very little more)
Mityvac testers have a good reputation. I'd recommend getting one that does both pressure & vacuum (& comes with all the extra bits for bleeding brakes etc as it costs very little more)
dsell
Addicted to ArboristSite
Take a look through this thread for general advice from others.
https://www.arboristsite.com/threads/pressure-testing.356230/
Use rubber sheets for gasket such as a truck or tractor tire inner tube.
I tested a Husky 455 strato and some of the pieces pictured here are from that test. You have to see what you can come up with. You could machine the pieces out of aluminum or metal if you have that capability. Polychrome is easy to work with and worked well for me. If you can find a workshop manual on your saw, it might show the special pressure testing tools to give you a plan. The first saws I adapted to were Husky 345/350 series, that's the small polychrome that fits the intake. You can adapt to the sparkplug hole, decompression hole, whatever you can adapt to. Maybe you use the hose from a compression tester and adapt to the sparkplug hole. The Echo rubber wedge in the picture is used to slide between the muffler or carb to block it off.
https://www.arboristsite.com/threads/pressure-testing.356230/
Use rubber sheets for gasket such as a truck or tractor tire inner tube.
I tested a Husky 455 strato and some of the pieces pictured here are from that test. You have to see what you can come up with. You could machine the pieces out of aluminum or metal if you have that capability. Polychrome is easy to work with and worked well for me. If you can find a workshop manual on your saw, it might show the special pressure testing tools to give you a plan. The first saws I adapted to were Husky 345/350 series, that's the small polychrome that fits the intake. You can adapt to the sparkplug hole, decompression hole, whatever you can adapt to. Maybe you use the hose from a compression tester and adapt to the sparkplug hole. The Echo rubber wedge in the picture is used to slide between the muffler or carb to block it off.
sawfan123
ArboristSite Member
Keep in mind, crank seals can leak under vacuum and not pressure.
Surprisingly, that instruction sheet doesn’t mention that.
For that reason, after you seal things with the inner tube
test vacuum first. Same spec.
Surprisingly, that instruction sheet doesn’t mention that.
For that reason, after you seal things with the inner tube
test vacuum first. Same spec.
Correct.
Interesting that Husky only ever reference pressure testing in their workshop manuals
Interesting that Husky only ever reference pressure testing in their workshop manuals
Backstage
ArboristSite Operative
That Mitivac is the one I ended up with. Very happy with it, and the little adaptors and plugs are essential.
Take off the carb and muffler. Cut a piece of rubber (you can get like 1/8” 4x4 rubber gasket squares at a good hardware store plumbing dept) using the muffler gasket as a template. screw on the muffler heat shield over top. Hse plugs in the carb ports. Detach the impulse lind (fuel lune from the carb that goes to the bottom of the cylinder. Attach your pressure tester to that and apply a good 10psi. It should hold positive pressure (unless your carb plugs cork out) and vacuum. If not, find the leak with soapy water.
It’s also good to try starting the saw and spraying carb cleaner at the seal points. If it dies immediately, that’s your leak.
Take off the carb and muffler. Cut a piece of rubber (you can get like 1/8” 4x4 rubber gasket squares at a good hardware store plumbing dept) using the muffler gasket as a template. screw on the muffler heat shield over top. Hse plugs in the carb ports. Detach the impulse lind (fuel lune from the carb that goes to the bottom of the cylinder. Attach your pressure tester to that and apply a good 10psi. It should hold positive pressure (unless your carb plugs cork out) and vacuum. If not, find the leak with soapy water.
It’s also good to try starting the saw and spraying carb cleaner at the seal points. If it dies immediately, that’s your leak.
Based on the saw your testing I'd skip the test and put new crank seals in it. That saw is known for leaky crank seals.
Only if it's a saw that has LOTS of hours on it. Most of them die long before any seals get worn, mainly because they come with a factory setting that is too lean and they are purchased by people who know nothing about chainsaws and can destroy any saw in short order.
Ok do a simple compression test first then and if it passes that then put seals in it.
