A REALLY dumb question!!???

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K7NUT

K7NUT

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I have been thinking about this since Saturday...
My 064 has a really bad leaky crank seal(clutch side) and so it acts just like the manual lists...
hard to start(if at all)
won't idle
runs at WFO only...:censored:

Now being a shady tree mechanic all my life, if a car or bike leaks oil out the crankcase, it still runs! Why does a Stihl not run when the crankcase seal is bad?
Remember, dumb question.:confused:
 
Not dumb, just not a 4 stroke.

When the intake charge enters the engine it is swirled through the crankcase. Through displacement, the piston can pump about half of the volume that is in the case up through the transfers to the combustion chamber. Because the piston moves up and down you have a suction pressure situation on each revolution. This is called impulse.

With a bad seal the fresh charge first is pushed out through the bearing, and then fresh outside air is drawn back in. What fuel remains of that intake charge is about gone by this time.

Dont run the engine any more untill you replace the seal. The next thing that could happen is the piston will scuff.

Best wishes,
Bob
 
just hope it's the seal. Take the clutch drum off, grab the crank and wiggle. A tiny bit of movement is normal and is maybe un in-noticible with the drum off. If it wiggles a lot, it's either the berring or the metal ring that is cast into the crank case in which the berring fits into. Which means you need another crank case and a lot of work.

Seals can be replaced easily enough without splitting the case or tearing apart the whole saw.
 
Air gets sucked into the bad seal and leans out the fuel/oil mix reducing its lubricative properties which leads to eventual siezure.
 
To add to what rmh3481 said, the carb also will not deliver as much fuel, which makes the air/fuel mix leaner.

Lean conditions lead to failure.
 
Thanks guys, the 2-4 stroke thing got me. I am going to check on the "wiggle" effect when I get home and don't worry, it's half torn apart now, so it can't run. BTW, how do you get the clutch off?:confused:

GM
 
I use a rope through the spark plug hole to stop the crank from turning. Bring the piston up just above the ports first so you dont get the rope down in them. Bring the piston up to the rope until the crank stops. Then remove the cluctch, remember the clutch is reverse threaded, clockwise removes it. I dont use impact with this method.
 
K7NUT said:
Thanks guys, the 2-4 stroke thing got me. I am going to check on the "wiggle" effect when I get home and don't worry, it's half torn apart now, so it can't run. BTW, how do you get the clutch off?:confused:

GM
Click to expand...

There are a couple of different ways to get the clutch off, there will be people that don't like either method, but they both work.

#1 buy a piston stop that screws into the spark plug hole, then using a wrench, take off the clutch (LEFT hand threads!!!)

#2 MAKE SURE THAT IT'S GOING THE RIGHT WAY (REVERSE), use short blips with an impact. If you do this, it's recommended to leave the spark plug in the cylinder head to create some back pressure. Some also suggest removing the flywheel just as an insurance policy against shearing the key. On an 064, there's an actual key, and it's not built into the flywheel, so if it does shear, it's just a key, not the whole flywheel. Oh, and do NOT use anything to "hold" the flywheel while you're using the impact. The impact will break it loose all by itself. If you try to hold the flywheel, sumptins' gonna break!

Hope that helps.. As I said, there will be some that agree, some that disagree with either method.

Good luck!
 
Evanrude said:
I use a rope through the spark plug hole to stop the crank from turning. Bring the piston up just above the ports first so you dont get the rope down in them. Bring the piston up to the rope until the crank stops. Then remove the cluctch, remember the clutch is reverse threaded, clockwise removes it.
Click to expand...

Okay, there's 3 ways.. ;) I'd forgotten about that one.
 
Oh, I guess I better say it.. Just in case.. :)

Don't use an impact with the piston stop! :) Ask Brad how thin the tops of these pistons are! (He knocked a hole in the top of a piston with just a piston stop and a wrench, although I think he also bent a crank that way, so maybe he's just a gorilla) :)
 
OK, like I promised, pic's, but the stick in the old spark plug trick didn't work. I need to figure out how to get the clutch off. I might just have to get a piston holder?:confused:
And oh yes, the beer, of course...
You can't get anything done without one, or two or three or...:givebeer:
<BR>
<BR>
<img src="http://mcallisterdrywall.com/AS/04-14-2009/0641.JPG"><BR>
<BR>
<img src="http://mcallisterdrywall.com/AS/04-14-2009/0642.JPG"><BR>
<BR>
You can see how bad the oil is leaking out and thats after I drained it back into the jug!
 
K7NUT said:
No, I took one stab at the spark plug thingy and it didn't work, then someone came over. Do you run the rope through the spark plug hole and out the Exhaust?:confused:
Click to expand...

NO

Before you put the rope into the cylinder make sure the piston is on the up stroke of the direction you're turning the clutch nut. In this case it will be clockwise. If you were to get the rope caught in the ports you'll cut the rope and have to pick out the pieces. Been there done that....:cry:
 
manyhobies said:
NO

Before you put the rope into the cylinder make sure the piston is on the up stroke of the direction you're turning the clutch nut. In this case it will be clockwise. If you were to get the rope caught in the ports you'll cut the rope and have to pick out the pieces. Been there done that....:cry:
Click to expand...

Exactly. Must be the OP didnt read my post explaining this already...:confused:
 
K7NUT said:
OK, like I promised, pic's, but the stick in the old spark plug trick didn't work. I need to figure out how to get the clutch off. I might just have to get a piston holder?:confused:
And oh yes, the beer, of course...
You can't get anything done without one, or two or three or...:givebeer:
<BR>
<BR>
<BR>
<img src="http://mcallisterdrywall.com/AS/04-14-2009/0642.JPG"><BR>
<BR>
Click to expand...

I just figured out another way to remove a clutch....: 1. Open bear 2. Remove spark plug. 3. Pour bear in through spark plug hole and fill cylinder. 4. Replace spark plug and the piston will hydro lock and allow clutch to be removed.

Disclaimer:This is just a joke and should not be tried!
 
manyhobies said:
I just figured out another way to remove a clutch....: 1. Open bear 2. Remove spark plug. 3. Pour bear in through spark plug hole and fill cylinder. 4. Replace spark plug and the piston will hydro lock and allow clutch to be removed.

Disclaimer:This is just a joke and should not be tried!
Click to expand...

I think you need a bigger disclaimer. Im sure someone will try it. Hehe :clap:
 

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