Pressure testing carb/crankcase

[thompson1600]

What pressure test kit did you buy, or how did you put one together to do the pressure test? Just a dial gauge, small hose and small pump (what kind did you use?)? Do you just use a rubber piece of somekind to block off the exhause port? What pressure do you go up to for it to hold? How long do you want it to hold pressure? Thanks

Tom

 

[Jacob J.]

Tom- cut several pieces of rubber from an old inner tube and use those and the muffler from the saw to block off the exhaust port. The only piece you need to buy for Stihl saws is the adaptor block which goes on in place of the carb, and if I remember correctly there is one adaptor that will fit several modern Stihl models. After that you just need a bulb/primer pump with a gauge and a hand operated vacuum pump with a gauge ( sometimes at auto parts stores you'll see a unit that does both ).

There's absolutely no need to buy the high priced Stihl pressure gauge/vacuum pump. Mostly you're just paying for the brand name.

Husky and Jonsered have their own intake adaptors for checking pressure/vacuum.

However, it's my opinion that 95% of the time you'll do just as good with a visual inspection of the cylinder base and oil seals for leaks as you will doing a leak-down test. In the time itakes you to set-up for a leak-down test you could pull the flywheel and clutch off most modern saws and visually inspect the oil seals, and that's your key area since the cylinder base and/or crankcase components are rarely compromised except in extreme operating conditions or factory defect.

The leak down test I've found more useful diagnosing valve problems on modern 4-cycle engines.

 

[stihltech]

pressure test

I have insured a lot of my repairs by doing the pressure and vacuum tests. It is mandatory when repairing a lean siezed saw. A visual insection is always a good way to start, and on many saws it will suffice, IF you are familiar with the trouble areas of that model. It is one of those things I do to keep the comebacks away.

 

[Al Smith]

Cheap pressure tester

An idea,that worked for me.I used the squeeze bulb assembley,valve ,guage,and hose,from an old blood presure tester.Cheap.$8.,e-bay,works great.

 

[G-MAN]

prower probe make an awesome pressure, vac. combination tester. it sells for about $100.00. it's the best i've seen around!

 

[Crofter]

What kind of pressures or vacuum should be considered maximum to avoid popping a seal?

 

[Grande Dog]

For Husqvarna you pump it up to 80 kPa ( 0.8 bar ), after 30 seconds it should maintain at least 60 kPa ( 0.6 bar ). If it falls below that you need to start searching. The old soapy water in a spray bottle works good for locating the leak.

Grande Dog
Master Mechanic
Discount Arborist Equipment and Tree Care Supplies

 

[tony marks]

if i was sellin saws ,id do what stihl tech does.. for my self ,i just get her warmed up and see if she got good torque an such.. in other wds if it gets the job done ,,like it should ,thats my pressure test..
assuming u know how to set a saw to run at its best..or at least as best, as u
are able to set it up..i aint to great at that but not bad either.. besides if i need real know how .. i know who to send it to. yall know my opinion on that..