Stihl 029 etc. Who is the freaking moron engineer....engine pan bolts

[Jedthro]

That is not my point- I care little what you do, what you have done in the past, present nor future.
You implied the design was at fault- I implied the design was never intended to be torn apart and upgraded by owners of consumer grade saws and using non OEM parts from dubious manufacture..

If that were the case, stihl would not sell individual parts and would instead sell complete motor assemblys.

 

[Jedthro]

Ive done the 029 to 039 swap and its a very good boost in power.
Like others have said ,I used oil 3in1 to lubricate the process and to be perfectly honest my wrist was sore from the slow tapping of cutting new threads with the bolt.
That cylnder was made to "NOT" have threads so they weren't forgotten. The process of putting the new bolts in helps hold everything together.
By the way a Pro Mac 7-10 is a clam shell design and it took most other manufacturers 25yrs to make a saw that would even come close to cutting with it in the 70cc class, McCulloch may have been an exception to rule but there are no hard fast rules to most things.

Now that my project is on hold till I get new bolts, I noticed HLSupply has the 49mm cross popup piston on their daily deal for 10 bucks....

 

[Bob Hedgecutter]

If that were the case, stihl would not sell individual parts and would instead sell complete motor assemblys.

But you admit to not using Stihl parts- mentioning soft aftermarket bolts and possibly harder alloy aftermarket cylinders.

 

[Maintenance supervisor]

Now that my project is on hold till I get new bolts, I noticed HLSupply has the 49mm cross popup piston on their daily deal for 10 bucks....

That's the exact same kit that I used.

 

[furb]

I used the oem bolts in farmertec cylinders. I’m not sure if they were tapped but the screws ran in easy enough with a cordless impact.

 

[Jedthro]

But you admit to not using Stihl parts- mentioning soft aftermarket bolts and possibly harder alloy aftermarket cylinders.

Of course. Oem is not just a little higher than aftermarket but almost an order of magnitude. It's not a collector saw, it cuts wood. There is no resale to worry about. It cuts wood.

 

[Bob Hedgecutter]

Of course. Oem is not just a little higher than aftermarket but almost an order of magnitude. It's not a collector saw, it cuts wood. There is no resale to worry about. It cuts wood.

Yes, but the beginnings of your post were a complaint about the design- you strayed a fair way from that design and things went bad.
The design works for the intended purpose, when others copy it for cheaper manufacture and supply- is the original design at fault?

 

[RED-85-Z51]

Historically i ram them home with an impact wrench...ive had hundreds apart and haven't noted any issues

Sent from my SM-G996U using Tapatalk

 

[Jedthro]

Yes, but the beginnings of your post were a complaint about the design- you strayed a fair way from that design and things went bad.
The design works for the intended purpose, when others copy it for cheaper manufacture and supply- is the original design at fault?

i still think its bad design. I doubt there is any benefit beyond cost savings. 4 less holes to tap in how many engines built is a lot of money.

 

[frank_]

i think the main benefit is the shakeproof high friction/self locking of the self tappers, i had done at least 3 stihl blowers that had the 3 crankcase screws shake loose and foul the flywheel or impeller, and they have the serrated underface too, but they are conventional metric threads
i dont recall any self tappers that came loose, you always need a t bar to remove them

 

[Chevboy0167]

I went through a similar process with a little Husky 137e. New OEM cylinder with no taped holes in base. New OEM crank seals and bearings, new OEM oil drive gear, new Meteor piston and rings. Re-used crank as Re-used the bottom pan as well as the 4 pan bolts. It took me a good hr to run them bolts in carefully and not snap the heads off. I admit I was a bit leary of that happening. Never thought of using an impact...lol And yes... my wrist hurt like h*ll too.

I too thought factory forgot to tap the holes and a few four plus letter words shot out of my mouth! But in the end I won and saw runs perfect.

 

[Mad Professor]

I guess when you are only paying ~$50 for a cylinder kit, buying some quality cap screws and tapping the holes might seem an expense.

I found black oxide coated carbon steel 6mm (1.0) X 50mm for $0.42 USD each. Stainless was lots more expensive.

 

[Jedthro]

I guess when you are only paying ~$50 for a cylinder kit, buying some quality cap screws and tapping the holes might seem an expense.

I found black oxide coated carbon steel 6mm (1.0) X 50mm for $0.42 USD each. Stainless was lots more expensive.

Nah, wasnt the cost rather ignorance on my part. I didn't think bolts sold for an application would turn out to be inferior.

Oh well, now I know...

 

[a. palmer jr.]

I know, but it's what I've used for the last 10 years strictly for firewood. Almost all are uprooted trees or trees taken down by pros that I would cut up.

I've been getting into some larger stuff, over 30" diameter the last couple years and the 029 works fine if I take my time, I just want a little more power so I bought a 49mm p/c for it. I then realized all I needed beyond that was a crank, pan and bolts to have a complete engine that I could just swap out.

According to my tap chart, it looks like I can tap an m6x0.75 still get 75% engagement. I guess that's the way I'll go with it.

I'm also going to assume it's bad practice to reuse these bolts on a new cylinder? I ran one in slowly, using cookies method and the treads on the bolt looked halfway stripped. Really seems to be a piss poor way of doing things.

I've always used the old bolts when installing a new aftermarket cylinder but then again, all of the ones I've bought are already threaded. It's probably a good idea to ask if the holes are threaded before you buy the kit...

 

[Jedthro]

I've always used the old bolts when installing a new aftermarket cylinder but then again, all of the ones I've bought are already threaded. It's probably a good idea to ask if the holes are threaded before you buy the kit...

That was the original plan but then I found I could get a replacement crank and an engine pan for like 40 bucks more, the bolts were all that was left to build a completely new motor and I could take the old one and just put it on the shelf.

More of a hobby than anything else.

 

[cookies]

They do not pre thread the bolt holes because they are self tapping very coarse threaded bolts meant to be run in and left, basically locking them in place. Even the oem cylinders are blank bolt holes, I did not trust the aftermarket cylinder metal being the same formula as oem hence my mentioned method. As long as the bolts reach the oem torque spec after install its golden, if your scared red locktite will make you sleep better at night until the day you have to take it back apart. The last oem cylinder kit ran me almost 200 squirrel nuts for a ms390, I have it saved for a rainy day emergency.

 

[Jedthro]

Have you ever seen one come loose tapping m6x1 with blue loctite?

 

[Jedthro]

The last oem cylinder kit ran me almost 200 squirrel nuts for a ms390, I have it saved for a rainy day emergency.

I gave less than that for the saw.....

 

[StihlSolo]

Yes, I've broken a bolt too. I just built a MS310. Build started out with a MS290 Mahle cylinder, snapped a bolt, tried extracting no go. So went ahead and got an oem 310 P&C (I already have an 039 that I built).

For the 310 I did a preassembly run. On an empty cylinder, tapped holes with a twist tap bit, cutting lubed, just a little to allow bolts to engage. Cleaned out the the shreds. Set bottom end dry to act as bolt guides, used old seals for alignment. Used cutting lube on both bolts and in holes, flooded the holes. Did 1/4 turns. Once all were tapped through, disassembled and cleaned up everything again. Then assembled everything with sealant and P&C lube.

In hindsight I think the bolts are good for one tapping run.

 

[Pioneer]

It was such a pleasure working on a Husqvarna 50, then I worked on the Stihl ms250 and its big brother the 310... I decided there must be a special place in hell for Stihl engineers, the ms250 in particular was nothing but torture for anyone to work on. |Their only saving grace is that when you finally finish your cursing and get them together they actually run not too bad.