Fixing 009 muffler

[Mad Professor]

I have a 009 top handle that started to get loud and rattle.

When I pulled off the recoil cover to access the muffler, I found the 3 self tapping screws which hold the cover had backed out and two were bouncing around loose. The screws had some aluminum in the threads so I assume the holes in the inner muffler housing are wollered out, and the screws won't hold.

I forgot to measure up the screws and the IPL I have don't have the screws shown. The saw is at my other place and I want to get screws in advance. The aluminum inner housing # is 1120 145 2805. It is same as this one:





Has anyone else done this repair with success so the the screws don't back out? The holes are not blind but I don't think there is room to get nuts on the other side, maybe. Might be able to grind the housing and/or nut.

My thoughts are larger self tapping screws (size?), through cap screws with nuts (size?), or drill and tap the muffler for a threaded Stihl screw (more work).

Anyway, trying to get parts in advance so I can do the work when I get back to the saw. I know best idea is to bring the muffler to the hardware store.


Will post pictures of the fix for people who run into this on 009/010/011.

P.S. I know some people don't like the 1120 series saws, but this little saw is in great shape, has the larger 38mm bore/41 cc, oil pump still works and runs and cuts great. The reed valve engine has good mid-range torque and cuts strong without revving the piss out of it.

I only use it for pruning my orchard, if a small limb comes down in my yard, or to take along ice fishing to get wood for fires.

 

[TLG]

I got a complete muffler for cheap if interested. So the cylinder mount is ok?? If not I should have a nice cylinder too.

 

[Mad Professor]

I got a complete muffler for cheap if interested. So the cylinder mount is ok?? If not I should have a nice cylinder too.

Besides the stripped out holes the muffler is fine. It's just the holes in the inner casing, that hold the outer cover/casing on, not the mounting holes in the cylinder. My P/C look fine through the ex port.

I have a friend who has a Stihl 010 that may need parts so I'll keep you in mind. What size bore is the cylinder?

 

[TLG]

I'll have to check on bore size. Let me know of any interest and I'll pull and measure//inspect I have it tagged as a good cyl. Thx. TLG

 

[Mad Professor]

I'll have to check on bore size. Let me know of any interest and I'll pull and measure//inspect I have it tagged as a good cyl. Thx. TLG

If you pull the muffler you can check the bore size with a plastic straw in the ex port. Crimp the straw with the piston and measure from the end to the crimp.

I think there is three size cylinders that fit, 36 38 and 40mm.

 

[TLG]

Yes, I get that for sure. But if your Bud needs a cylinder I would like to inspect it. Just don't want to waste the effort if not interested that's all. TLG

 

[Mad Professor]

Yes, I get that for sure. But if your Bud needs a cylinder I would like to inspect it. Just don't want to waste the effort if not interested that's all. TLG

I'll give him a holler and see what's up with his saw. Not sure that the cylinder is toast. He ran it with the air filter not sealing and he said it ingested some debris.

 

[Mad Professor]

I got to working on the saw. Had not been taken down with clutch and flywheel off, in 2-3 years? Spent a good time on cleanup.........clutch side was ugly.

Went with drilling and taping the holes for 5 X 20mm stainless cap screws. Plenty of metal to drill out the old holes. Also an excuse to buy some more metric tap/dies and bits to prep the holes.

What is best way/cleaner to remove oil/carbon from an aluminum ex housing? Can't cook it like a steel one.

Good news is P/C look great as can still see original machine marks in the piston.

 

[Mad Professor]

Update. I have the muffler repaired.

Oven cleaner helped get some of the crud off but was harsh on the aluminum that was bare.

Original screws (3) appeared to be Stihl 3.9mm X 13mm self-tapping (same as screws for the spark screen and handle cover/molding). They are not shown in the 009 IPL.
Used:
5mm-0.80 X 20mm stainless cap screws (3)
5mm stainless lock washers (3)
5mm- 0.80 tap
Drill bits. 11/64”/0.172” /4.4mm (for tap) and 7/32” (for cover, a little sloppy for 5mm screw).
Note that 5mm tap calls for a #19/0.1660" drill bit but could not find one quickly
11/64” is a bit oversize (0.006”) but 5/32” is 0.010” too small.

Some pictures of the strange muffler this Stihl series use and the fix: