Stihl 038 AVS Farm Boss (late ‘80s) worth saving?

[Ratman]

Ok kids before I upload lots of detailed shots of the cylinder and piston outside and in - is the crank supposed to have as much wiggle as this? Hoping videos are allowed here. More pics to come. Cheers

Side to side movement is fine, you dont want any up down movement between the con rod and crankshaft if that makes sense to you.

[Wonky]

Arr the crudd I was cleaning the last few days.. and a few mistakes I made  🤦‍♂️
 

i fooked one side of a case.. the crud hid a case screw 🤬 that means one case half is well and truly knackered… I’ve helicoiled  ore two other threads.. but this repairing of small 2stroke saw is something I enjoy..as a part time thing.. it helps to learn to  maintain  everything else.  And not ruin the exspensive stuff.

the fugged case one is spare parts now 🤣

🙈
I will say @Rough Hewn got me these saws and  few other (junk)  saws,

that's a few 018's. There old monsters compared to the new 181's epa's mincie saws…

[Ratman]

This is as far as I got @spudulike et al - the cylinder to my untrained eye looks like it may have some deposits but to me it does not look very scored. What should I be looking for when taking in the heady sights and smells of a head assembly soaked in oil and WD40? I’m gonna take a break until the brain trust has spoken (please remember I know nothing, in fact, less than nothing, and any advice is mega welcome!).
cheers all [emoji846] 

From your pics i think the cylinder will probably clean up well and you’ll get away with fine emery/light hone but hard to be 100% sure without sticking a thumb nail in there [emoji6]

[Wonky]

Umm. I like to read but one finger typing is crap.

i like to play with saws. And share my learnings , so you mabe lucky.

 

but I,m not on here that much as I like to play 😉👍

 

thease old saws… in their80's may have seen a little or a lot of use.

so my advise is to change the bearings while you there doing the rest of other bits and bobs..

 

 

yes it’s a pain but it’s worth it in the long run/time as the two 038's with pto bearing problems were down to the cages holding the bearings in place seemed to be knackered and the bearings were all around one side.

 

to change the crank seals means stripping it clutch &flywheel off and all the bits to get to them.

so really it’s not that much more  to split the crank… or is it.  I’ve got one to do soon. I hopefully will get it on vid. My smacking it hard etc..

 

then once it’s sorted it will have a longer life than if I just changed the crank seals and then if a bearing was to go … you be at the same place as before .

 

ask me about a 200t I put China bearings in 🙈 the seals were fine (026 flywheel seals) that’s why i said about simply bearings  ..I’m going skf for thr 038..

 

 

 

 

[spudulike]

I would check the main bearings for play by moving the crank end and flywheel up and down, forward and back and if you can feel no play then carry on 

I say this as to do the bearing work will require splitters and a 10" G clamp and a good engineering background. There is much that can go wrong and if the bottom end is sound, leave it well alone.

Cleaning - I use white spirit, cheap paint brushes and a compressor.

The cylinder looks reasonable. Rub those streaks of transfer with wet and dry, apply acid or strong alkali, when it stops bubbling, clean and rub a little more and repeat until no bubbling is present. You then need to rub the cylinder to roughen the bore and so you can't feel any high points on the cylinder surface. A hone does this and is what I use but you can get by with just abrasive paper. 

How were the manifold and impulse? If you have no pressure/vacuum pump, check the rubber parts and tune the carb a bit rich to ensure the repair lasts. 

 

Edited March 30, 2022 by spudulike

[Wonky]

Looking at your pic of the intake side piston and cylinder I’d  say you do have a pto bearing problem. And the front side (exhaust) shows the air leak. 
lve  some pics for you. And a redneck case splitting vid that will make spud cry 😉🤣👍

I think the crank on this saw is past it’s best

these fag bearings seem to break & loose the plastic cage, if you look closer at the fw side you can see the crack in it where as the pto side is gone

[Wonky]

The case splitting 🙈

lve done a few of my own saws like this..although I should spend about £80 to buy a China case splitter.  where this was done cheap and quick with a bit of springy steel and an angle grinder to cut a slotted bit for the bar nuts. The other end is in a bench vice. It’s a shame the floor is so far away.🤫 so it’s best I don’t recommend my way to split the cases

 

[Wonky]

This pic shows the case half I broke (bottom of pic) because I missed a case bolt due to the crud and me being lazy 🙄

 although I though I,d show the case half I split today (top of pic) and the same sort of crud as to why I missed it the first time.

pits a shame but it’s not the end of the world. As I said I was gifted 3 x 038 nonrunning saws that I intend to make 2 out of 

[spudulike]

The intake damage on the piston is often when the build up of transfer on the exhaust side pushes the piston backward and against the inlet port side causing a mini seize.

A bad bearing is more likely to scuff the sides of the piston.

If the machine is going to get some serious use, you want to learn a bit and are a bit masochistic, fill your boots, otherwise, just check for play like I said.

You could pull the clutch side seal to check the cage further but up to you and your ambitions. Splitting and rebuilding a saw is generally a bit beyond most unless you have been around engines a good time.

[Just_Alex]

9 hours ago, spudulike said:

The intake damage on the piston is often when the build up of transfer on the exhaust side pushes the piston backward and against the inlet port side causing a mini seize.

A bad bearing is more likely to scuff the sides of the piston.

If the machine is going to get some serious use, you want to learn a bit and are a bit masochistic, fill your boots, otherwise, just check for play like I said.

You could pull the clutch side seal to check the cage further but up to you and your ambitions. Splitting and rebuilding a saw is generally a bit beyond most unless you have been around engines a good time.

Thank you @spudulike, I’ll have a wee bit of time with it this weekend and will check play and hoses. From what I’ve researched it seems to do that properly I need to remove the handle/tank from the crank case, right? 
Couple of other questions: assuming the cylinder is serviceable, which grit do you recommend using in terms of sandpaper? I have a bunch of higher wet-and-dry grits here, just not sure how high to go. Also, do you wrap the paper round your finger or perhaps use the old piston as a template for a “sanding block” of sorts to not accidentally overdo any one area? 
And when it comes to the piston itself, we are replacing that, correct? Or just sand and new rings? Any links to recommended / favoured piston kits to use? I’ve been searching online and getting Option Paralysis 😂, and I saw you recommend Meteor etc before but I’m not sure which retailer to go through (same for OEM auf that’s the case). 

You said in an earlier reply “You then need to rub the cylinder to roughen the bore” and I’m trying to digest this- do you mean we use chemicals to get rid of transfer, then abrasive to make even and smooth, and then use a different/lower grade grit to make it a bit rough again? If so- why do we do that and which grits would you recommend for each step?

I’m also planning on using MotoMix - are there any other rubber parts I should consider at this junction? Fuel line / filter I assume as well?

 

So many questions. I apologise. You’re a saint for putting up with me.