Author Topic: I know it's a stupid question -- can't get flywheel off pro mac 10-10  (Read 828 times)

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Offline strad

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I've got what I think is probably bad crank seals.  it'll idle (but it idles too fast) but falls on its face when it gets any throttle.  It started doing this rather suddenly.  Carb is clean.  Looking through the intake port (carb removed), I can see scoring on the piston.  Doesn't look too bad but no way to really know for sure inspecting it that way.  I did get the flywheel nut off, but the flywheel is stuck on the shaft.  Pulling up by hand on it does not budge it.  I have pullers, but I really don't want to bust this thing up by doing something wrong. 

I also haven't tried to remove the clutch assembly yet -- was going to work one side of the problem at a time hehe.  So any suggestions would be great.   

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Offline Warped5

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Put the nut back on there 1/2 way or so ... lay the saw on its side - flywheel up.  Grab a flat area on one fin with some vise-grips and lift .... now give that nut a good whack or two.

Offline brokenbudget

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don't bother with the vice grips. there's enough room to grab the flywheel with one hand if you remove the coil. set the nut down until it's flush with the top of the threads. put the socket on the nut and give it a sharp blow with a hammer. should pop off easily.
when I grow up, i wanna be an adult.

Offline Al Smith

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The 10 series of McCullochs are by far the easiest saws ever made to work on .On a non AV mount style such as the 10-10 I can have one completely disassembled in about 20 minutes .

Scuffing on the intake side of the piston is not uncommon because of the rather poor design of the air filter .Not to worry you'll never know it's scuffed once it's running .

Now you do as you like but to change seals I usually take the engine apart rather than  dig them out with a drywall screw .It's a clam shell design with 4 small bolts on the outside and 4 larger inside the oil tank which is the front of the crankcase .

If you can't get the flywheel off once to pull it apart a little tap of a hammer usually knocks it loose .Not big ball peen hammer now .A small dead blow,wooden mallet ,lead hammer or block of wood cushioning the blow .

Offline strad

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Ok.  I now have the thing all apart.  It took me longer than 20 minutes Al (!)  Next time will be faster  Anyways, the piston looks mostly okay.  I can see the scuffing, but can't feel it with my fingers.  I'm concerned about the cylinder though.  Especially the exhaust side of it.  I've posted pics of the cylinder and the piston.  I can most definitely feel the scoring in the cylinder with my finger.





So what do I do about the cylinder and/or the piston, and where can I get the crankshaft seals?  Btw, I should mention that our family has had this saw since I was about five years old.  We got it and I remember seeing it used when we still lived in Oregon.  So it has lived in Oregon, Illinois, California and Nevada over the past 35 or so years. 

Offline Al Smith

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Get a Scotch -Brite pad and use kerosine ,diesel fuel WD -40 and clean the cylinder of what little bit of tramp aluminum it has in it .You might sand off the piston a tad too using real fine paper with kerosine .Don't get too carried away it doesn't have to be smooth as silk .Get the high spots off is all .

Usually a low spot will be okay,the high spots break the surface tension of the oil film .Once you get it together run it on 32 to 1 mix it should be okay .

Seals probabley the easiest would be Randys engine repair in Seamans Ohio .They are standard SAE sized seals but most bearing houses have to order them. All told you can get them from Randy Duncan about as cheap . http://www.randysenginerepair.biz/servlet/StoreFront      He sells on flea bay as well as others .

The large seal on the flywheel side should be mac #67906 and the smaller on the clutch side 110260. If you can't find them I can cross reference them with CR seals .

Offline Al Smith

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It that's an iron lined cylinder which it appears to be you can hone it .If it's chrome don't attempt it . If  worse comes to worse I have some decent pistons I could part with .Fact I've probabley got a decent cylinder or two but I can't be certain if it's a left hand or right hand start .

Offline strad

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Not sure what you mean by left or right hand start.  I can tell you that the starter cord is on the opposite side from the bar and clutch.  That would be the left side of the saw.  I have all the parts cleaned.  I took a small piece of green scotchbrite and did a little work on the cylinder, mostly on the exhaust side.  Although I can see the scoring all the way up to the top, I can feel it only near the bottom.  And I can feel it less now that I did a little work with the scotchbrite.  I did not do a compression test before I took it apart (I don't have the right adapter for my compression tester), but it sure felt like it had excellent compression.  The piston rings are not stuck.  One question.  I was able to insert the piston back into the cylinder without the help of a ring compressor (which I have).   The end of the cylinder has a taper to the liner, almost like a ramp, which I assume helped me to insert.  So the fact that I was able to do that -- does that mean the ring's fit in the cylinder is too loose?  or am I good to go? 

Oh, and I used my fingernail to remove what looked like clear sylicone all around the mating surfaces of upper and lower crankcase halves.  Should I use something similar to put it back together, or should I use permatex gasket maker of some type?

Offline Al Smith

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That's the way all McCulloch are made ,with a chamfer.The early  clam shells they used something like Indian head gasket shellac which is just thin Permatex .The later ones they used RTV .Either one will work .I personal use Indian head or Permatex number 2 .

FWIW I have never used any type of ring compresser on any chainsaw engine I've ever worked on .On say a removable cylinder like most Stihls if you do it correctly with a little wiggle here and there you can stuff the piston slick as anything .

Offline strad

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Well I'm somewhat impatient lol.  I called Randy's shop this morning and got a no service beep beep beep.  So I emailed him and got no response within an hour.  So I contacted Chainsawr in VT and got one of the seals, and then I found oldmowerparts in IN and got the other seal.  I ordered two of each so the next time I work on a 10 series I'll be covered.  I think I'll take my chances with the cylinder.  The scoring is there, yes, but it's probably not the worst thing to ever happen.  I'll just run it on 32:1 and see what happens. 

 

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