Stihl 036 scored piston?

[arrow]

Well if anything BG its a learning experience. As a former logger for 30 years, i discovered a little about chainsaws but mostly when they wouldn't start or minor mechanical or fuel path difficulties. I never had a saw (any saw) last more than a couple -3 years before it was wore out and tossed and never had the inclination to rebuild any one of them. May have saved some money but I was too wore out at night to start messing with saws that were past. Kind of regret that and am pulling for you to get this saw "as new"

 

[LD1]

Sounds like you got a good handle on it. I agree to get a new cylinder. Dont try to save that one IMO.

And the one pic of the piston shows the deal with the rings that I was talking about.

 

[Baby Grand]

Thanks for the positive thoughts, arrow. I'm pretty beat from my cubicle job by the time I get home, but tinkering with the saw is interesting and I've always enjoyed turning wrenches. Plus, the more designs you fully examine, the better your design "sense" gets. I steal ideas from everywhere I can!

 

[Baby Grand]

Captains log, day 21 ... still no sight of land.
Got all my parts and tools & started to begin the job of reassembling the new jug & piston, when I noticed something.
What's wrong with this picture?

 

[LD1]

That aint gonna work. Are those the bolts that came out of the base?? Most saws use either an allen head or a torx head bolt so you have clearence. Probabally an 8mm. You may have to get some new bolts with the right style of head. Thats what the holes through all the fins are for, so you can get at them with a torx driver:thumbsup:

 

[xyz123]

Using wrong bolts with huge heads that wont clear creating angle.


Didnt you say you used a torx 27 to remove the cylinder bolts? Thats what should have been in there torx 27 heads.

BG you said you had a service manual. Better start using it. All the bolt sizes etc are listed. Cylinder bolts. 036 = IS-M5x20


I just looked you said torx wrench to remove cylinder bolts.

Okay, got the jug off last night after some difficulty. The long series of holes through the fins on the jug/head were misaligned with the bolts and almost exactly the same diameter as my Stihl torx scrench - so the bit wouldn't engage the bolts. Typical, shoddy German engineering! Sorry, as an American engineer, I couldn't resist...
Had to open up the holes in 2 locations with an N sized drill to seat the bit:

 

[Baby Grand]

Guys - sorry about the confusion - my fault in expressing myself poorly.
Allow me to explain:
I have all the bolts laid out on a board, in the shop, just as I removed them.
I didn't want to disturb my "dirty teardown layout", so I just gabbed 2 bolts to show my dilemma.
What can I say - I'm a little OCD about this stuff.

What I was trying to show is that the surfaces that the bolt heads bear against weren't machined,
and are far from being parallel to the machined flange that mates to the crankcase .
The Torx bolts would sit in there the same way.
It's as-cast & the flange faces have about a 7 or 8 degree draft angle to them.
Even if I could torque those bolts to spec without snapping heads, they won't last long once I start cutting.

I did get a Wiha 2.7mm torque wrench along with a red, plastic ring compressor kit and a flywheel removal tool for 22/26mm-1.5 pitch.
I'm all about doing this job by the book (service manual). Just this setback put me off my game plan a bit.
Very disappointing to have all the stuff finally ready to go, only to discover that the star of the show isn't ready to play ball.

So I went to Harbor Freight and got their 6" x-y cross slide vise.
I'm going to do something foolish and use it on my drill press to mill the flange faces as flat as I can get them.
I'll be taking very light cuts with a 5/16" 2 flute end mill and will have the jug tightly clamped to a 1/2" steel plate with
the flange oriented vertical and 3 of the flange bolts securing it to the steel plate.

Like shooting fish in a barrel - if I don't hit my foot.

 

[xyz123]

Thanks for explaining it. I can see what you were showing now. The oem one is flat across.

May I ask what brand cylinder that is?

 

[LD1]

Thanks for explaining it. I can see what you were showing now. The oem one is flat across.

May I ask what brand cylinder that is?

That would be my question as well, if the OEM one truly is supposed to be flat. IDK, I never had an 036 appart.

On a side note, I think you will be fine milling it. Its just cast aluminum and cuts easy. But I would use a 4-flute, and with a 5/16 cutter and aluminum, I'd be zinging at about 2500rpm if your press will go that high.

 

[Baby Grand]

Thanks for explaining it. I can see what you were showing now. The oem one is flat across.

May I ask what brand cylinder that is?

48mm Cylinder Kit for Stihl from Northwood Saw for $89.95.

 

[LD1]

A few questions:

Have you tried contacting them?? IF you look at the photo on their website, it looks like it is machined flat for the bolt.

Also, is the cylinder you got chrome plated or NiSi (nikasil)?

Cause if it is chrome, I wouldn't touch it yet. I'd send it back. You can get the NWP aftermarket kit that IS NiSi coated of only $30 more. Well worth it IMO. And NWP is one of the better "low cost" aftermarket companies.

Either way, I am still curious to see what northwood has to say

 

[Baby Grand]

A few questions:

Have you tried contacting them?? IF you look at the photo on their website, it looks like it is machined flat for the bolt.

Also, is the cylinder you got chrome plated or NiSi (nikasil)?

Cause if it is chrome, I wouldn't touch it yet. I'd send it back. You can get the NWP aftermarket kit that IS NiSi coated of only $30 more. Well worth it IMO. And NWP is one of the better "low cost" aftermarket companies.

Either way, I am still curious to see what northwood has to say

No, I haven't tried contacting them - I'll give it a try - good suggestion.
If I don't get satisfaction from Northwood, and I do trash the part, then I'll get the NWP one and eat the expense as a lesson to myself that often you get what you pay for. I had second thoughts about getting the cheapie when I ordered it.

I'm getting impatient to get this project moving again, so not sure I really want to go through the whole mail it back & wait thing. Other than the the unmachined flanges, it does look like a good quality part, and I don't see the milling op as being a major risk. And yes, it's NiSi coated.

It's a big adventure!

 

[MasseyWV]

Looking good so far. :thumbsup:

 

[LD1]

No, I haven't tried contacting them - I'll give it a try - good suggestion.
If I don't get satisfaction from Northwood, and I do trash the part, then I'll get the NWP one and eat the expense as a lesson to myself that often you get what you pay for. I had second thoughts about getting the cheapie when I ordered it.

I'm getting impatient to get this project moving again, so not sure I really want to go through the whole mail it back & wait thing. Other than the the unmachined flanges, it does look like a good quality part, and I don't see the milling op as being a major risk. And yes, it's NiSi coated.

It's a big adventure!

If its NiSi coated, then thats a plus. Seems the only issue now is the mounting flanges. I would def. call them. Northwood seems like a big online place. If anything, you will see what kind of business they are

 

[Baby Grand]

If its NiSi coated, then thats a plus. Seems the only issue now is the mounting flanges. I would def. call them. Northwood seems like a big online place. If anything, you will see what kind of business they are

Message sent with photo. Hope they are willing to deal.

 

[LD1]

keep us posted. this has got me very interested.

 

[Baby Grand]

Response is that unfortunately sometimes these after market kits require some tweaking before installing.
They offered me $25 store credit for my trouble diddling with it or they would swap with another part.
Not sure the replacement would be any better, so I'm taking the credit and will proceed with the plan to mill the sucker flat.

 

[LD1]

Yea, I dont think I would want a replacement unless they could confirm it was okay.

But hey, $25 credit is well worth the phone call:thumbsup:

 

[Baby Grand]

Yea, I dont think I would want a replacement unless they could confirm it was okay.

But hey, $25 credit is well worth the phone call:thumbsup:

It certainly is, and thanks for the suggestion to try!
I was so frustrated and embarassed by getting sucked into the whole cheaper-is-better thing that I honestly hadn't even thought of contacting them.
I'll post again as soon as I have made some chips.

 

[Baby Grand]

Ack! I messed up the smaller of the 2 replacement oil seals.
Was having great luck seating it with a 3/8" drive socket & a ball peen hammer.
Everything was going well until I noticed that the seal was .060 - .080 below the flange face.
Hand spinning the crank didn't feel right, so I ordered a new seal and will be careful to choose a tool that is larger than the bore the seal fits into next time. Lesson learned.