064 - >066 hybrid air leak

[Kwood]

Alright here goes,

As the title says I performed my 2nd 064 to 066 big bore conversion, not sure if that's relevant to this issue though..

After the swap I pressure/vac tested, found a leaking Flywheel side crank seal, replaced that. Then found a leak at the clutch side bearing seat in the crankcase. Bearings are fine so I Fixed the leak by vacuuming loctite into the leak spots. Bolted her up and the idle screw had no affect. It ran great, however. Put in a carb kit just in case. Idles at 2600 and tached to 10500 to be on the safe side. When on its flywheel side the idle runs high indicating an air leak.

I tore it down and it passed vac test perfect, failed pressure. Thinking it was the bearing seat again, much to my surprise I found that to be holding fine under pressure, which was a relief. I found the air leak coming from the oiler line at the chain tensioner(where the oil line compression fits to the bar). I removed the oil pump and plugged the outlet hole from the oil tank(where the oil pump compression fits into the oil line) and it built pressure, indicated when I released my thumb. When plugged it also leaked at a small hole in the middle of the chain tensioner(see pic), not sure what that is.
Can anyone lend some advice as to what the problem could be? Air must be getting into the oil tank from somewhere but I don't know much about that area and how it connects to the case, I didn't think it did... I'll do more research but thought this was an interesting issue to have so I posted here. Any help is much appreciated !

Also the saw compression tests to 165 after a half tank of fuel, new fuel line, and carb boot also.

 

[HarleyT]

Look at a pic of the blowup, more specifically, the crankcase gasket.

 

[kenton.a.frank]

Leaking through gasket in oil tank?


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[L34]

The case gasket that is between the 2 case halves is leaking into the oil tank.

 

[Kwood]

I was hoping that wasn't the case, but I've been skirting along that line since the bearing seat leak... So I'll need to split the case then. Dang.

Time to do some more research... So that crank seal was a waste of $23. I don't suppose there's a way to salvage the seals. I'll do the bearings for sure but the one seal is new and the other is fine.

 

[blsnelling]

Sounds like you are going to have to spilt the case.

 

[pioneerguy600]

The seals are likely toast but you could try heating the half crankcase up to 300F and then slamming the case half down hard on a wooden bench/ plank or other flat surface, often times the bearing will fall out without damaging the seal.

 

[HarleyT]

The seals are likely toast but you could try heating the half crankcase up to 300F and then slamming the case half down hard on a wooden bench/ plank or other flat surface, often times the bearing will fall out without damaging the seal.

You Canadians play rough!!

 

[PA Dan]

I was hoping that wasn't the case, but I've been skirting along that line since the bearing seat leak... So I'll need to split the case then. Dang.

Time to do some more research... So that crank seal was a waste of $23. I don't suppose there's a way to salvage the seals. I'll do the bearings for sure but the one seal is new and the other is fine.

You're going to have to buy a gasket set and seals are included! You paid $23 for one seal? Ouch!

 

[Kwood]

J

You're going to have to buy a gasket set and seals are included! You paid $23 for one seal? Ouch!

Yes! Tell me that's exorbitant, I want to stay oem for bearings and seals but the price seems ridiculous for what they are. That's from my local and only stihl dealer in town, if there's a better way to order oem that I'm unaware of please enlighten me and help my wallet.

 

[Kwood]

Sounds like you are going to have to spilt the case.

Likely so... To be honest, while it's a royal pia costs wise, I do enjoy learning something new. Rebuilding my 57 massey fergusons cav injection pump was fun.

Just a thought, I haven't inspected the oil trough with flashlight, but if I can pinpoint the leak by peeking in (assuming I can see the halves, then maybe I could pull a vacuum and try the loctite method yet again. It would be a band aid at best, but it would be nice to have my saw working properly for the first time since purchase without shelling out more cash. Any thoughts?

 

[PA Dan]

J


Yes! Tell me that's exorbitant, I want to stay oem for bearings and seals but the price seems ridiculous for what they are. That's from my local and only stihl dealer in town, if there's a better way to order oem that I'm unaware of please enlighten me and help my wallet.

Look up @definitivedave for Stihl parts!

 

[kenton.a.frank]

I’ve pulled one side and resealed before without messing up the other sides seal. I don’t know locktites ability seal under constant oil and the pressure of the case.


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[HarleyT]

OOOzing loctite into nooks and crannies of a running saw sounds like a real bad idea!!

 

[pioneerguy600]

You Canadians play rough!!

It takes what it takes John, when in the backwoods camps we didn`t have everything on hand so we made do with what we had til fresh supplies were brought in. One becomes very self reliant when things have to be fixed and not every part and piece is readily available.

 

[HarleyT]

I've heard stories of you "burly boys" in backwoods camps!!!!

 

[Kwood]

OOOzing loctite into nooks and crannies of a running saw sounds like a real bad idea!!

It's certainly not my first choice, and may not even be possible. If the leak is anything like the leak in the bearing race to crank seat than it takes an u noticeably small amount to fill the spot and then wipe the excess, it then hardens in the absence of oxygen. Smart? Certainly not, but the worst case would likely be a burnt bearing from grit getting in right? Which means a split case anyways. I like to follow the motto of do it right the first time, as that typically holds true in the end...but I am tempted to try, if possible.

 

[grizz55chev]

I've heard stories of you "burly boys" in backwoods camps!!!!

 

[pioneerguy600]

I've heard stories of you "burly boys" in backwoods camps!!!!

Self reliance again ,ole buddy.

 

[pioneerguy600]

It's certainly not my first choice, and may not even be possible. If the leak is anything like the leak in the bearing race to crank seat than it takes an u noticeably small amount to fill the spot and then wipe the excess, it then hardens in the absence of oxygen. Smart? Certainly not, but the worst case would likely be a burnt bearing from grit getting in right? Which means a split case anyways. I like to follow the motto of do it right the first time, as that typically holds true in the end...but I am tempted to try, if possible.

You are not the first one to do this, it has worked every time for me thus far, applied vac to the chassis and the Loctite got pulled in. Two 064`s and a 460 still running fine with this fix.