SXL-130 Pressure Test

[edju1958]

I've had this SXL-130 for well over 1 1/2 yrs.now.When I first got it I fired it up & it wanted to run at almost WOT.I rebuilt the carb & still had the same problem.About 3 or 4 months ago I pulled it down to do a pressure test & just never got around to doing it.Rather than start another rebuild on my SXL-922 (that's next) I figured I'd get this monkey off my back first.As I said,the clutch is off & the flywheel (it has the blue coil of death).I made block offs from an old inner tube & put them under the muffler & carb.Tomorrow I need to locate the Schrader valve (?) that a friend made for me a couple of yrs.ago & put my MightyVac to good use.I have a spray bottle of soap water to put on the crank seals & the cylinder gasket area where I can access it.

        Just to err on the side of caution I pulled the reed assembly to make sure all was in order there.Wouldn't you know it,when I pulled the reed cage out the retainer stayed behind & 2 of the reeds fell off & down into the engine.I guess I got lucky by turning the saw upside down & shook it till the reeds fell out.I wasn't easily amused by those antics.I have new crank seals to replace the current ones & I hope it's not more involved,i.e.cylinder gasket,but if I need to replace that I will.

[kevinm1980]

Sept 7, 2021 20:02:15 GMT -5 edju1958 said:

I've had this SXL-130 for well over 1 1/2 yrs.now.When I first got it I fired it up & it wanted to run at almost WOT.I rebuilt the carb & still had the same problem.About 3 or 4 months ago I pulled it down to do a pressure test & just never got around to doing it.Rather than start another rebuild on my SXL-922 (that's next) I figured I'd get this monkey off my back first.As I said,the clutch is off & the flywheel (it has the blue coil of death).I made block offs from an old inner tube & put them under the muffler & carb.Tomorrow I need to locate the Schrader valve (?) that a friend made for me a couple of yrs.ago & put my MightyVac to good use.I have a spray bottle of soap water to put on the crank seals & the cylinder gasket area where I can access it.

        Just to err on the side of caution I pulled the reed assembly to make sure all was in order there.Wouldn't you know it,when I pulled the reed cage out the retainer stayed behind & 2 of the reeds fell off & down into the engine.I guess I got lucky by turning the saw upside down & shook it till the reeds fell out.I wasn't easily amused by those antics.I have new crank seals to replace the current ones & I hope it's not more involved,i.e.cylinder gasket,but if I need to replace that I will.

How did it go?

[edju1958]

It didn't go well at all.I couldn't get any pressure at all.I even made new block offs to be sure it wasn't that causing the problem.Either there's a massive air leak (doubtful),or the way of pressurizing is all wrong.I'll just end up putting new seals in & hope that was the problem.If it wasn't the seals,then I'll throw the saw in the corner & part it out at a later time.Thoroughly disgusted.

[kevinm1980]

Unless a seal is missing I'd be surprised if that is what's causing a air leak that bad, I could be wrong let us know, thinking it could be cylinder gasket or intake manifold gasket, or a crack?

[tangobravo]

Having tried making some block offs and sealing one up for testing, I was unable to get any meaningful results too. I think you are better off with tip testing and visual looks at the seals for excess oil pushed out when diagnosing these for failure. I'd make them prove they need replacement before changing them out.

[edju1958]

No seals missing,they're both there,otherwise the saw wouldn't run at all.

Visual tests of seals can be deceiving.On the Jonsered saw that I just replaced the seals on they looked fine,even after I pulled them out.I put the new seals in & the high idle at the tipping stopped.FWIW,tip tests aren't always accurate either.Replacing seals is a guessing game IMO.In order for the saw to have such a massive leak I'd have to lean towards a cylinder gasket gone bad,or a combo of bad seals & a bad cylinder gasket.Maybe as long as I'm going through the saw I should do a compression test too,I did see some slight scoring on the piston on the exhaust side,but nothing major.Possibly do a gasket replacement too.Hell,might as well cover all the bases.

     I've been down this road before & I got laughed off the site,but I'll mention it again.I'll see if the ignorant ones rear their ugly heads again.A chainsaw repair guy who's been in the business for over 40 yrs.told me to go out & buy a pack of cigars of my choice & a can of PlayDough,color of choice,& put the PlayDough in the carb around a fuel line stuck in the throat of the carb,light the cigar & take a puff & blow the smoke into the fuel line.Kink the hose so the smoke can't escape & then watch where the smoke leaks out.He said you'll find your leak sure as shootin'.He said do this or go buy yourself a smoke machine that costs a bunch of money.This is how old timers fixed saws way before the MightyVac was on the scene. 

[tangobravo]

Maybe some kind of rubber hose- like a heater hose section could be put over the crankshaft end and used with a vacuum pump or pressure pump easily?? Something like that should be developed to test the darned things!

[stillsawing]

I like your idea of using a smoke test. If the saw turns out to be a complete piece of junk, you can convert it into a bong.

[edju1958]

Now we're going back to the 70's,Lol.

[stillsawing]

I take it that you can not hear air hissing. Not knowing anything about the SXL-130, do they have a decompression valve?

[edju1958]

I couldn't hear any air hissing because it wouldn't hold any pressure.The saw has no decompression valve.Some of the saws in this series had the decomp valve while others didn't,no rhyme or reason as to why or why not.