What would make this seal tear? (036)

[drf256]

What's would make this OEM seal tear?

I built this 036 from the ground up. Case split, new OEM bearings and seals.

Seals oiled before pushing in. I put electric tape over the crank threads and keyway before sliding the seal over as to not damage the lip.

The PTO bearing was frozen, the oil pump attached, and the case heated. The bearing literally dropped right in and the pump set its depth.

No play in the bearings at all. I don't not believe that the seal lip rolled out during assembly.

Here's the jug. Just 25 from the band to clean it up and a base cut to get squish to .019 with an oem base gasket.

Timing with gasket came in at 106/126/80. Muffler modded and key advanced .025. No port work at all.

 

[drf256]

Here's the video. The saw starts out set to 14300. It's painfully long. At about 1:15 it starts to leak, you'll see me start to richen it after each cut, then you'll see it idleing at about 8000 rpm when the air leak s becomes massive.

 

[drf256]

So I pressure/vac test it, and it's got a huge leak. Won't hold anything.

 

[drf256]

I trace the leak to the PTO seal. I find this...

 

[drf256]

Here's some pics of where the bearing is located in the case. Again, it's brandy new. I think I may have pushed the seal in too deep and the crank caught the inner part. It's all I can think of.

The 036 has a step in the crank that a washer and sleeve sit against to locate the oil pump worm gear. So as long as the seal is past that stop, it shouldn't rub on the washer.

 

[Mattyo]

yikes...

slap a new one in and go for it? see if it tears again?

 

[drf256]

That's done already. No time to run in daylight till Friday.

 

[Mattyo]

it looks like someone jammed a screwdriver in there ...... wow

 

[lwhaples]

No guesses,but am interested to hear how it turns out.

 

[Backtroller]

Me too. I wonder if rubber wasn't formed correctly from the factory but the outside looked ok?

You are meticulous. I doubt you would have missed something on assembly.

 

[Mastermind]

Just a fluke....

 

[Chainsaw Jim]

Good thing it exposed itself before shipping it back.

 

[malk315]

Whole new learning opportunity thanks for sharing Al. The end idling at 8000 as it draws more and more air and less fuel... Primitive version of strato

Hope you get to a root cause. I'm thinking bad seal I agree that you are very precise about things. Hopefully nothing is catching that seal.

BTW my 262 was throwing chips like mad saw at GTG with Dan's square chain... And no leaky tank didn't even stink during the car ride.


Sent from my XT1585 using Tapatalk

 

[Mastermind]

I'm trying to acquire all the correct seal tools. Having them sure speeds things up.

 

[smokey7]

I have 2 strokes that backfire and blow seals out or apart. Did it ever do anything funny like that?

 

[Moparmyway]

Is this boogers on the crank ?
It looks like the little divots could have torn the seal
They show up in more than one pic

 

[Mastermind]

Damn good eye Clint.

 

[Moparmyway]

Damn good eye Clint.

Yeah Clint .............. Dang good eye

 

[drf256]

Kev, that's just dirt. Was sprayed and wiped clean before the next seal went in.

I'm perplexed.

 

[Onan18]

Kev, that's just dirt. Was sprayed and wiped clean before the next seal went in.

I'm perplexed.

After seeing those pictures I am going to say bad seal as well, chit happens.