Stihl 066 magnum...bad news??

[Jason280]

After chasing a few problems on my newly acquired 066 Magnum, I decided to do a pressure test. I first tried pulling a vacuum on the fuel tank, but didn't have much luck. I never was able to pull a vacuum using a Mity Vac, but was actually able to pressure the system through the fuel line. Not sure if that is indicative of anything, but I don't believe that is my real issue.

I blocked off the carb using a piece of flat aluminum over a double thick piece of rubber inner tube...



...and did pretty much the same with the exhaust:



I tried pulling a vacuum with the Mity Vac through the impulse hose, but was never able to pull anything. I then tried blowing throw the same hose, and definitely have a leak. It was difficult to narrow down, but it sounds suspiciously like its coming from behind the clutch assembly here:



I assume this is likely the clutch side crank seal, but not positive. Assuming it is, what am I in for, and how difficult of a job am I facing? Do I need to tear down the saw further to confirm?

Any suggestions? Thanks!

 

[gunnusmc03]

Seals are an easy repair, spray a little soapy water where you suspect a leak. With pressure then soapy water will bubble up where ever there's a leak.

 

[z71mike]

Yank the clutch and oil pump. Get down to the seal and go from there.

 

[Jason280]

Question is, how do I get to the seal? Is the clutch assembly a pain to remove?

 

[gunnusmc03]

Just need a piston stop and a scrench. The crank is left hand threads though, righty loosey.

 

[z71mike]

Stuff a rope down through the plug hole at TDC, as a piston stop. Then impact the clutch off.

 

[fearofpavement]

If you use an air impact, don't put rope or any other kind of piston stop in the engine. It's just not necessary for one thing. Don't even need to have the spark plug in, it'll come off no prob.

 

[Jason280]

Snap On MG725 should make short work of the clutch, I'll try to get it pulled in the morning, Anything else I should check/change while I'm there?

 

[watsonr]

Change both seals. If the saw has lots of wear and tear, changing the impulse, fuel line and filter is cheap insurance.

 

[hseII]

Change both seals. If the saw has lots of wear and tear, changing the impulse, fuel line and filter is cheap insurance.

Those hoses are cheap in comparison to having to revisit this.
if you have go this far, replace all seals and hoses and be done with it.

 

[Jason280]

Change both seals. If the saw has lots of wear and tear, changing the impulse, fuel line and filter is cheap insurance.

I've already changed the impulse hose, fuel line, and filter, as well as rebuilt the carburetor. I'm getting ready to pull the clutch side seal, except no one locally has a replacement. Closest option is 45 miles away, so I have to decide if I want to order it or drive.

 

[watsonr]

Want your cake now or later....

 

[Jason280]

Exactly...im considering going ahead and swapping out the flywheel side seal as well. I'm sure the dealer has a Stihl seal puller, so I may try to con them into pulling both for me when I pick up the seals.

Are both sides reverse threads?

 

[z71mike]

Exactly...im considering going ahead and swapping out the flywheel side seal as well. I'm sure the dealer has a Stihl seal puller, so I may try to con them into pulling both for me when I pick up the seals.

Are both sides reverse threads?

No. Flywheel side is normal thread. And yes, do both seals at the same time.

If you're friendly with your dealer, maybe he'll help you out. But I don't know a dealer who would do that for free. It's easy enough to do it yourself with a modified carb screwdriver. Don't be afraid!

 

[Jason280]

I may try pulling them tonight, just to see how difficult they may be....sounds like its time to notch a screwdriver or two!

 

[z71mike]

Now that's the spirit!

 

[lwn9186]

To save some money, but the whole gasket set. Seals will be included with the gaskets.

 

[MrGiggles]

Just be really careful not to put a scratch in the case. Be careful with the crank too, but you'd have to try pretty hard to damage that.

Sometimes a drywall or sheet metal screw can be screwed into the edge of the seal. Grab the screw and try to yank the seal out..

 

[cedarshark]

I replace seals with the Stihl puller. Sometimes I replace seals now just to enjoy how well the puller works.

 

[Jason280]

To save some money, but the whole gasket set. Seals will be included with the gaskets.

What all is included in a complete gasket set?