026 Grief

[drf255]

Sure sounds like a vacuum leak to me as well. I’m with Bob.

You can check the impulse line by visually checking while flexing it an blowing/sucking air through it.

Running well at WOT and not idling is the sign of a vac leak. The other issue on the model is a lip in the intake snout that will puddle up after a while and make saw stall.

The Achilles heel of that model is the flywheel side seal. It’s usually where the leak occurs. Another common issue is the choke flap malfunctioning, so try it without the airfilter, won’t cost u a thing.

 

[Overlooker]

When blasting the carb cleaner through the passageways,

You should be very conservative with carb cleaner and your air hose when cleaning a carb. Zama specifically forbids blowing anything through the various orifices on their carbs, because it might cause permanent damage to check valves. Also, I have heard that carb cleaner can swell the rubber tip on your needle valve. Consider using an ultrasonic cleaner to clean your carb body. If you watch 7 different YT videos about carb cleaning, I guarantee you will get at least 9 different opinions on the right way to do it! T-A

 

[Mad Professor]

It's the muffler bearing for sure...............

 

[a. palmer jr.]

I usually dip the carburetor in carb cleaner after disassembly, then dip it in hot water then blow it off with compressed air. Don't put the needle valve or the spring in carb cleaner!

 

[GCTS]

OK so the new impulse line and the mityvac finally came in... In the meantime I re-cleaned the carb being careful to rinse with water and dry afterwards this time. Haven't put the saw back together to try the carb again because I wanted to wait for the new impulse line first.

First time testing pressure & vacuum so I hope I got it right. Tested by blocking the carb port (with carb removed) and muffler port with drilled steel plates and bicycle inner tube, reinstalling the spark plug, and testing through the new impulse line. After trying to hold for a bit, I pulled the cord to move the piston a bit and see if it still held.

Pressure looked great - held 8psi without dropping every time. Vacuum not so much... no matter how fast I pumped, it would never quite get up to 10 inHg, and would drop off quickly to about 6inHg and stay there for a while. I'm not sure if it might have been something wrong with my setup, or if that's an indication of a leak around the crankcase? Any suggestions where to go from here?

 

[pioneerguy600]

Apply some hard grease or heavy oil around the seals at the crankshaft ends, then re test. Seals are likely leaking under vac. I usually just pull 7 lbs vac, that is enough for chainsaw seals.
Just came across this post again, 7 lbs vac is incorrect, 7 inHG is the correct term.

 

[PV Hiker]

Might try one side at a time with the grease to see witch one is leaking.

 

[GCTS]

I remembered reading to test around 7lbs for vacuum, but my Mityvac reads psi for pressure and inHg for vac... I was assuming to aim for around 7 inHg - does that sound right? I could get it up to about 9 inHg at the top of the pumps, but each time I opened the handle for another pump the needle would drop down to about 7 right away, then quickly trickle down to about 6. I assumed it should go to around 8 or so and stay there? This picture is with the needle dropping on its way down to about 6. Am I reading this right that there is a vacuum leak?

 

[drf255]

Grease oir squirt oil around flywheel side seal. You will need a puller to remove the flywheel. I bet it holds 15 inch of Hg, or you can watch the oil get sucked right into the seal under vacuum.

 

[GCTS]

You guys are amazing - grease on the flywheel side seal stopped the vac leak until the grease started to get sucked in. Looks like the clutch side is still sealing. Just ordering the flywheel side seal from the dealer now Now I have to decide which of the hacks I've seen here to use to try to pull off the seal without wrecking the bearing... Hoping not to have to buy the puller. Any recommendations?

 

[Mad Professor]

You guys are amazing - grease on the flywheel side seal stopped the vac leak until the grease started to get sucked in. Looks like the clutch side is still sealing. Just ordering the flywheel side seal from the dealer now Now I have to decide which of the hacks I've seen here to use to try to pull off the seal without wrecking the bearing... Hoping not to have to buy the puller. Any recommendations?

Don't be a stoop.

Whole gasket set, costs less than seals alone; do BOTH seals.

 

[Overlooker]

You guys are amazing - grease on the flywheel side seal stopped the vac leak until the grease started to get sucked in. Looks like the clutch side is still sealing. Just ordering the flywheel side seal from the dealer now Now I have to decide which of the hacks I've seen here to use to try to pull off the seal without wrecking the bearing... Hoping not to have to buy the puller. Any recommendations?

Ditto. If one seal is bad, replace both. I own the China-made puller which worked well on my 036 but not on my old Homelite XL 923. I had to use a pick and a modified screwdriver. You might have to get creative. O

 

[a. palmer jr.]

The clutch side seal is easy to get off but the flywheel side needs a little more expertise. You can use a modified screwdriver to get it off if you're careful. Just grind your screwdriver end into an "L" shape at the end and it will hook under the seal, taking care to not scratch the crankshaft surface or the engine block where the seal sits. Don't get in a hurry.

 

[drf255]

If you tap one side of the seal in, the other side will pop out. Then just grab the edge that pops out with a pair of needle nose pliers.

You have to remove the key from the crank before you put the seal in. In addition, measure seal depth and take a pic before u pull seal so that you know how deep to put the other one in.

 

[Ronie]

The clutch side seal is easy to get off but the flywheel side needs a little more expertise. You can use a modified screwdriver to get it off if you're careful. Just grind your screwdriver end into an "L" shape at the end and it will hook under the seal, taking care to not scratch the crankshaft surface or the engine block where the seal sits. Don't get in a hurry.

That's what I use.

 

[a. palmer jr.]

That's what I use.

Mine's similar, I found it's not good to use a cheap screwdriver for this as the Chinese ones break when you put much pressure on them..

 

[GCTS]

Thanks - that's super helpful to see a picture, and good to know about the cheaper screwdrivers. I was thinking of grinding one of the little orange stihl ones that come with saws. Is it safer to insert the tool into the outer or inner edge of the seal, or does it matter? I'm assuming the screw trick is a riskier approach due to the likelihood of introducing drilled shavings into the bearings?

 

[Ronie]

Thanks - that's super helpful to see a picture, and good to know about the cheaper screwdrivers. I was thinking of grinding one of the little orange stihl ones that come with saws. Is it safer to insert the tool into the outer or inner edge of the seal, or does it matter? I'm assuming the screw trick is a riskier approach due to the likelihood of introducing drilled shavings into the bearings?

If your talking about the little carb adjustment screwdrivers, they would be to small. Here's some pics of me prying out a seal, you just want to catch the inner lip so you don't mess up the seal pocket..

 

[a. palmer jr.]

Thanks - that's super helpful to see a picture, and good to know about the cheaper screwdrivers. I was thinking of grinding one of the little orange stihl ones that come with saws. Is it safer to insert the tool into the outer or inner edge of the seal, or does it matter? I'm assuming the screw trick is a riskier approach due to the likelihood of introducing drilled shavings into the bearings?

You can use the screw trick if the seal is big enough, like on the clutch side of an 026. The flywheel side seal is a different story, the seal is too narrow to get any kind of screw in it, you just about have to use a puller. Use the puller between the crankshaft and the lip of the seal but be very careful so as not to scratch the crank. Stihl makes a puller but it's too pricy for me...

 

[atpchas]

Some other approaches:
https://www.arboristsite.com/community/threads/slide-hammer-seal-removal.240189/