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

[spudulike]

Right...use battery acid, brick cleaner or a strong alkaline solution to eat the aluminium transfer away. Start with around 180 grit once the acid/alkaline has done its job and then try more chemical as it will oxidise the transfer surface and then you take off the surface to let the chemical work again. 

Once the bore is pretty clean, roughen up the surface with the wet and dry so the new piston beds in...the 180 or a bit finer will do the job but don't go mad with it.

Fit a new piston, OEM Stihl, Meteor and Hyway are best and them Golf and VEC who I suspect are the same Indian manufacturer or take your chances with a no brand type.

No need to remove the tank, just remove the cylinder, the inlet manifold bellows should come off with the cylinder and the impulse should be easy to remove and inspect once the cylinder is off.

Motomix....fit a new carb kit- I think Stihl used Bing carbs on some models and either Zama or Walbro on later units so ensure you identify carb type before ordering the kit. Rowena are very good but may not take a single order. A new fuel line and filter would make a lot of sense.

When it is working again, tune the carb to run rich to protect the saw and avoid any issues  

[adw]

You cannot use sand paper sir, you need emery cloth and plenty of oil, just use your finger with the emery cloth, use a fine emery cloth and work on the ares that has the aluminium transfer, cross hatching I guess Spud is referring too is going around the complete bore in a random motion this will help remove any glaze and leave a cross hatch finish.

[spudulike]

As above, go around the bore as if you abrade up and down in one area, you can create a slight cavity in the bore and get issues with blowby past the ring. Just do it lightly and let the chemical do the heavy lifting.

[Just_Alex]

Well, perhaps time for an update, as I have spent some quality time with the old hornet today. I’m fairly certain there is no axial or lateral wobble on the crank shaft, can feel nothing move at all. Clutch is still attached though, not sure if that makes a difference. 
In the end I could not get to the impulse line (clumsy fingers) so I did take the tank off (wanted to clean under there anyway) and as far as I can see there is no visible crank case seal oil leak anywhere, but maybe it’s too early to tell, as there is still plenty of gunk to get rid of.

Impulse line removed and inspected. Aside from stiffening over the years there was nothing wrong with it, to my surprise. I have ordered new tubing from LS. 

 

I also had a careful look at the crank shaft bearing by rotating it all the way with a pointy thing to make sure the race is not broken (poor @Wonky!). Bearing race looks good. 

 

Questions I have: 

1. Boot- can I remove that from the cylinder side by tugging/gently prying? Or do I need to work from the carb side and remove the carb first? ( @spudulike if I proceed to the MotoMix side I’ll need to remove the carb anyway…). I’m having a hard time inspecting the boot for cracks in position so would like to replace it I think. 

 

2. The crank case / tank case mounting: are the black rings supposed to be attached to the plastic tank assy or are they broken off “slices” of the rubber AV mounts? 
 

3. Good idea to replace the river AV mount grommety things all over I assume? 
 

4. is there supposed to be any fleece filling inside the air filter? Looks like nylon webbing front and back but is empty inside for me which I found odd, but maybe it’s intended this way. 
 

5. The drive shaft on the sprocket side- I can see some tempering colours on the steel- from dark straw to blue and back to straw. Is this caused by normal operation or is this a symptom of overheating in the past? 
 

6. The oiler set screw at the base of the crank case seems a bit weepy, is that normal? I’ve not tried unscrewing it but maybe there’s an o-ring in there that might want to be replaced?

 

Anyhow, I am rambling. Thank you all for all your input, I’m trying to learn as fast as I can, and am actually enjoying this. If it weren’t for you I’d probably have sold the saw in parts or something, I don’t know. I might still fail here to get it back to life but I’ll have learnt a lot. 😊

[spudulike]

The impulse line looks like a length of fuel line that L&S sell in Meyer lengths so just purchase 1m and cut to length.

Remove the carb and boot support ring and the boot can be pushed through the air box back and withdrawn from the tank moulding and will then come off with the cylinder and is held on with a metal clamp.

The AV mounts...best replace them ..not sure about the other stuff you mention about them ..worth looking at the parts list and seeing what the bits you talk about are shot or not. If the rubber disks are the bits on the front tank mount, they look OK but worth fitting new if perished. They are buffers!

The crank looks OK, no pitting that I can see so OK despite the colour.

You have inspected the big end cage....the bit you rotated with the pointy thing....good thing to do if you have big scores in the bore.

Just clean, inspect and replace what is shot. 

The carb will obviously need removing and check for type.

 

 

[Just_Alex]

Thank you Spud, sounds like I’m vaguely ambling in the right direction. Tomorrow I hope to clean and inspect the head a little closer, I’ll see what acids I can get my hands on too. I’ll remove the carb to see what type it is and hopefully unseat the boot. 
I checked out of curiosity and sadly L&S don’t have 50mm piston kit listed in stock as far as I can see. Where do I go - eBay? Not sure how rife it is with imitations of the replicas (as a novice I don’t want to end up buying a piston that says it’s Meteor but ain’t, if you see what I mean).  
I’m trying to work out if the 50mm piston from the 044 will fit the 038 av super, but maybe that’s just the Google algorithm confusing me…

If anyone has a trusted source of parts and could link me to their website that would make me eternally grateful. I really like the way this site collates the 038 parts but if I can avoid import duties / get better quality parts that would be great 😂 https://shop.saegenspezi.de/Passend-fuer-Stihl-br-038

 

Thanks all!

 

[peatff]

28 minutes ago, Just_Alex said:

I’m trying to work out if the 50mm piston from the 044 will fit the 038 av super, but maybe that’s just the Google algorithm confusing me…

 I think the 044 is a longer stroke than the 038. 

[Just_Alex]

9 hours ago, peatff said:

 I think the 044 is a longer stroke than the 038. 

This makes sense thanks @peatff 👍🏻

[spudulike]

I usually use eBay for non OEM parts but there isn't much available out there. Not sure what you are going to have to do....trouble with old saws!

[Stubby]

22 hours ago, Just_Alex said:

Well, perhaps time for an update, as I have spent some quality time with the old hornet today. I’m fairly certain there is no axial or lateral wobble on the crank shaft, can feel nothing move at all. Clutch is still attached though, not sure if that makes a difference. 
In the end I could not get to the impulse line (clumsy fingers) so I did take the tank off (wanted to clean under there anyway) and as far as I can see there is no visible crank case seal oil leak anywhere, but maybe it’s too early to tell, as there is still plenty of gunk to get rid of.

Impulse line removed and inspected. Aside from stiffening over the years there was nothing wrong with it, to my surprise. I have ordered new tubing from LS. 

 

I also had a careful look at the crank shaft bearing by rotating it all the way with a pointy thing to make sure the race is not broken (poor @Wonky!). Bearing race looks good. 

 

Questions I have: 

1. Boot- can I remove that from the cylinder side by tugging/gently prying? Or do I need to work from the carb side and remove the carb first? ( @spudulike if I proceed to the MotoMix side I’ll need to remove the carb anyway…). I’m having a hard time inspecting the boot for cracks in position so would like to replace it I think. 

 

2. The crank case / tank case mounting: are the black rings supposed to be attached to the plastic tank assy or are they broken off “slices” of the rubber AV mounts? 
 

3. Good idea to replace the river AV mount grommety things all over I assume? 
 

4. is there supposed to be any fleece filling inside the air filter? Looks like nylon webbing front and back but is empty inside for me which I found odd, but maybe it’s intended this way. 
 

5. The drive shaft on the sprocket side- I can see some tempering colours on the steel- from dark straw to blue and back to straw. Is this caused by normal operation or is this a symptom of overheating in the past? 
 

6. The oiler set screw at the base of the crank case seems a bit weepy, is that normal? I’ve not tried unscrewing it but maybe there’s an o-ring in there that might want to be replaced?

 

Anyhow, I am rambling. Thank you all for all your input, I’m trying to learn as fast as I can, and am actually enjoying this. If it weren’t for you I’d probably have sold the saw in parts or something, I don’t know. I might still fail here to get it back to life but I’ll have learnt a lot. 😊

Alex you are like a Jack Russel on a rat . I love it !