pressure/vacuum test via spark plug hole?

[half_full]

Sorry for the potentially stupid question.
Can I use my compression tester hose with quick disconnect to do pressure/vac testing?
My thought is that the piston/ring would interfere.

I can make a plate for the exhaust if I have to. Just looking for easiest way to test on a 55 rancher

 

[Steveo_supremo]

Yep, it'll work. I test saws that don't have an impulse line that way. Make sure You take the valve core out of the bottom of the hose.

 

[asdf4240]

Sorry for the potentially stupid question.
Can I use my compression tester hose with quick disconnect to do pressure/vac testing?
My thought is that the piston/ring would interfere.

I can make a plate for the exhaust if I have to. Just looking for easiest way to test on a 55 rancher

I'm not sure this is a good way you still need to block off the intake, exhaust, and impulse line. And depending on where the piston is in the compression stroke it will pass, example if it's under full compression. The reason for doing a pressure test is to test the integrity of the case not the combustion chamber, thus the reason for using the impulse line.

Note saws with good compression create 150psi and good cases hold pressure at 10 psi (or Hg).

 

[half_full]

I'm not sure this is a good way you still need to block off the intake, exhaust, and impulse line. And depending on where the piston is in the compression stroke it will pass, example if it's under full compression. The reason for doing a pressure test is to test the integrity of the case not the combustion chamber, thus the reason for using the impulse line.

Note saws with good compression create 150psi and good cases hold pressure at 10 psi (or Hg).

Thanks for the replies. The impulse on the 55 is direct from cylinder to carb. Wouldn't vac/pressure slowly equalize due to minute ring gap?

I was going to use an innertube chunk to make a cover for the muffler and carb and bolt them back on. Like in this thread

http://www.arboristsite.com/chainsaw/42768.htm

 

[jus2fat]

I can make a plate for the exhaust if I have to. Just looking for easiest way to test on a 55 rancher

The easiest way to make the blocking is to use Eternabond Tape..!!

http://www.arboristsite.com/chainsaw/182878.htm

See photos...can be found at Lowe's...

It looks like you can get the small stuff at Walmart...3" x 24"...$9.96

http://www.walmart.com/ip/Eternabond-Microsealant-Tape/10825191

J2F

 

[brokenbudget]

I'm not sure this is a good way you still need to block off the intake, exhaust, and impulse line. And depending on where the piston is in the compression stroke it will pass, example if it's under full compression. The reason for doing a pressure test is to test the integrity of the case not the combustion chamber, thus the reason for using the impulse line.

Note saws with good compression create 150psi and good cases hold pressure at 10 psi (or Hg).

if you put the piston at btc, you ARE checking the case integrity. what difference does it make where you fill the engine with air on a 2 stroke?
if your not rotating the crank while checking for leaks, you're not doing it right.

 

[redunshee]

if you put the piston at btc, you ARE checking the case integrity. what difference does it make where you fill the engine with air on a 2 stroke?
if your not rotating the crank while checking for leaks, you're not doing it right.

If you're checking via the impulse line, piston needs to be at TDC. Exactly opposite of using the sparkplug hole.

 

[redunshee]

if you put the piston at btc, you ARE checking the case integrity. what difference does it make where you fill the engine with air on a 2 stroke?
if your not rotating the crank while checking for leaks, you're not doing it right.

Only time I rotate the crank is when doing a vacuum test for seal integrity. Should be no need to rotate crank for a pressure test.

 

[blsnelling]

IMHO, piston position is a non-issue. Rings do not create an air tight seal.

 

[brokenbudget]

Only time I rotate the crank is when doing a vacuum test for seal integrity. Should be no need to rotate crank for a pressure test.

i do it for both. they should hold.

 

[Streblerm]

IMHO, piston position is a non-issue. Rings do not create an air tight seal.

I almost always pressure test saws through the plug hole. I use my leakdown tester with the regulator turned down all the way and then gradually bring the pressure up. I have vacuum tested them this way as well, with a vacuum pump of course. I like to spin the crank over while under vacuum/pressure to test the seals. The gauge bounces a little when you do this but there is no change on the gauge when it settles down

Be careful using quick couplers. I spent quite a bit of time chasing down a leak that turned out to be a leaky coupler. The simpler the hoses between the saw and the gauge, the better.

 

[kykayaker27]

learning alotopcorn:

 

[Log Hogger]

Bailey's carries Husqvarna's spark plug adapter for pressure testing, Husqvarna part no.: HVP 503 84 40 02

I think Stihl sells an exhaust port plate w/hose barb, but being a Stihl part it probably costs as much as it would to replace the bearings, seals, and case gasket on a Husqvarna, lol. I guess if you have a welder the plate w/barb would be easy to make.

 

[half_full]

The easiest way to make the blocking is to use Eternabond Tape..!!

http://www.arboristsite.com/chainsaw/182878.htm

See photos...can be found at Lowe's...

It looks like you can get the small stuff at Walmart...3" x 24"...$9.96

Walmart.com: EternaBond MicroSealant Tape: Plumbing & Fixtures

J2F

Thanks for all the replies. I was expecting someone to tell me I'm a dork and do it a different way.
I did see the eternabond thread as well. I just figured I'd like to make something. I'm a tinkerer. I was thinking of breaking an old spark plug and welding a barb on there. I agree with making it as simple as possible to rule out any connections.

 

[old 040]

Thanks for all the replies. I was expecting someone to tell me I'm a dork and do it a different way.
I did see the eternabond thread as well. I just figured I'd like to make something. I'm a tinkerer. I was thinking of breaking an old spark plug and welding a barb on there. I agree with making it as simple as possible to rule out any connections.

never hurts to spray soapy water at all posible places where a leak could occure, including the tester hose and fittings (pressure test), and watch for bubbles

 

[brokenbudget]

never hurts to spray soapy water at all posible places where a leak could occure, including the tester hose and fittings (pressure test), and watch for bubbles

i fill the 'lip' of the seal around the crank while doing the vacuum test if there seems to be a problem. if the liquid 'sinks' in or gets pulled in, you have a leak.

 

[old 040]

i fill the 'lip' of the seal around the crank while doing the vacuum test if there seems to be a problem. if the liquid 'sinks' in or gets pulled in, you have a leak.

i'll have to try that on the next vac test, what type a liquid do you use, seams like the lighter the better

 

[brokenbudget]

i'll have to try that on the next vac test, what type a liquid do you use, seams like the lighter the better

gas o leeeeen!:msp_thumbup:
or just the same old soapy water. a little being sucked in won't hurt anything.:smile2:

 

[Eric Modell]

Windex is a good fluid to test with.

 

[brokenbudget]

Windex is a good fluid to test with.

not really. the ammonia in it will eat the rubber seals if left long enough.