Stihl 032 AVE rebuild

[OneStaple]

Ok, some of you convinced me to rebuild my 032 instead of selling for parts, especially since it ran well until I let it sit on a shelf with gas for a few years. It currently won't run, likely because of the carbs. And pulling the muffler shows some wear on the piston, but perhaps not enough to scrap it. There's a lot of carbon build-up around the muffler port too (see pictures, one at TDC, one in the middle, and one at BDC).

I'll be asking questions as I go, but here's some initial info.

• I got this saw used about ten years ago. I replaced the broken impulse line (which is why I got it cheap) and a couple things (filters, etc.) before pressing it into service. No full overhaul at that time.
• I think I replaced the intake boot back then, but it's been too long and I don't totally remember.
• Before this tear down, compression test says 165 psi (cold).

Things I plan to fix/replace/repair:

• Open up the piston/cylinder. Check for any additional damage to verify if this is worth the investment, and otherwise clean things up (carbon buildup, etc.) and put back together.
• New rings on the piston. This seems like a smart move once I have things open.
• Do a carb kit.
• New crank seals?
• Gaskets at all applicable locations.
• New AV mounts. They're all toast
• Clean fuel and air filters. Replace if necessary. Do they make a better air filter for this saw?
• Fix stripped threads, replace missing bolts.
• Hope everything works, tune it, and go have fun with it.

Let me know if there are other things I should be doing/checking

Tyler

 

[OneStaple]

Ok, first up is the vacuum test...

I put a piece of rubber inner tube between the exhaust port and muffler to seal that. The intake port has a rubber boot on it with no really good way to clamp a piece of inner tube in place. So, I just put on a rubber glove and shoved my finger in the boot to seal it up. Not perfect, as I could see the vacuum level drop if I wiggled my finger too much, but I think good enough for this test.

I pulled vacuum to 15 inHg. I let it sit for 5 minutes (again, still using my finger to seal), and rotated the crank about five times between the 2 and 3 minute marks. By the end of 5 minutes, it had gone down to 14 inHg. There's a decent chance that the lost vacuum was due to an imperfect seal with my finger, especially as I turned the crank. But based on what I read, I think this passes the vacuum test regardless. Do you all agree?

My Mityvac only reads vacuum. It can put out pressure, but the gauge doesn't measure it. I put some pressure in through the impulse line (same setup as above), and after a minute, heard a *puff* as I removed my finger, suggesting that some level of pressure remained. Given the results of the vacuum test, do I still need to get a gauge and run the pressure test? I suspect the answer is yes.

Also, if I pass vacuum and pressure, is there any value in replacing the crank seals?

Thanks,
Tyler

 

[tomalophicon]

Ok, first up is the vacuum test...

I put a piece of rubber inner tube between the exhaust port and muffler to seal that. The intake port has a rubber boot on it with no really good way to clamp a piece of inner tube in place. So, I just put on a rubber glove and shoved my finger in the boot to seal it up. Not perfect, as I could see the vacuum level drop if I wiggled my finger too much, but I think good enough for this test.

I pulled vacuum to 15 inHg. I let it sit for 5 minutes (again, still using my finger to seal), and rotated the crank about five times between the 2 and 3 minute marks. By the end of 5 minutes, it had gone down to 14 inHg. There's a decent chance that the lost vacuum was due to an imperfect seal with my finger, especially as I turned the crank. But based on what I read, I think this passes the vacuum test regardless. Do you all agree?

My Mityvac only reads vacuum. It can put out pressure, but the gauge doesn't measure it. I put some pressure in through the impulse line (same setup as above), and after a minute, heard a *puff* as I removed my finger, suggesting that some level of pressure remained. Given the results of the vacuum test, do I still need to get a gauge and run the pressure test? I suspect the answer is yes.

Also, if I pass vacuum and pressure, is there any value in replacing the crank seals?

Thanks,
Tyler

Before I got a pressure tester I used a cheap bike pump with a gauge. Worked well.

 

[MnSam]

It sounds like the seals are decent. It would be best to test with the crank play fully to one end and then the other (as in running it and tipping it on its side). I suppose this could be replicated statically as well. If it was me, I wouldn't mess with the seals unless you need to. Just learn to listen for a lean condition every time you run it, something you should be doing anyway. To me that piston looks fine. You could take it down and decarbon and re-ring it if you want a project. I would be tempted to leave it as is. Go through the carb, replace the fuel line/filter, clean the air filter, replace the AV mounts. As long as you are running appropriate mix and the electronics hold up it should last you many more years.

 

[OneStaple]

It sounds like the seals are decent. It would be best to test with the crank play fully to one end and then the other (as in running it and tipping it on its side). I suppose this could be replicated statically as well. If it was me, I wouldn't mess with the seals unless you need to. Just learn to listen for a lean condition every time you run it, something you should be doing anyway. To me that piston looks fine. You could take it down and decarbon and re-ring it if you want a project. I would be tempted to leave it as is. Go through the carb, replace the fuel line/filter, clean the air filter, replace the AV mounts. As long as you are running appropriate mix and the electronics hold up it should last you many more years.

Well, I'm not looking to take it apart and decarbon it just for the sake of doing so or because I don't have other things to keep me busy. So if it's not actually needed, then I'm fine leaving it as is.

My impression is that it's still worth cleaning out the carbon buildup in the exhaust port though, correct? So it doesn't flake off and fall back into the cylinder. Any suggestions on a good way to do that? Fine wire brush and anything else I can find to scrape it out, then vacuum and/or compressed air? Do it with the piston blocking the port or at BDC? I've seen both methods suggested. With the former, carbon could potentially get below the rings and into the crank. With the latter, I'd have to be careful to blow out the chamber when done.

I went ahead and got a pressure gauge to do a pressure test. Finding a way to block the intake port wasn't easy on this saw. I ended up putting gorilla tape over it and then clamping a small block of wood over that. Using my finger with a rubber glove as I did on the vacuum test quickly proved to not work.

Initial pressure was 10 psi. After 10 minutes, it had dropped to about 9.9 psi. Five crank rotations later, it was the same. So it appears that I now passed both the vacuum and pressure tests!

So, new plan (assuming everyone agrees with Sam's assessment). This should be much cheaper/faster/simpler. I'll still get to have fun with a full rebuild on my 051.

• Clean carbon from exhaust port
• Do a carb kit.
• New AV mounts. They're all toast
• Clean fuel and air filters. Replace if necessary. Do they make a better air filter for this saw?
• Fix stripped threads, replace missing bolts.
• Hope everything works, tune it, and go have fun with it.

Tyler

 

[OneStaple]

Ok, I have the saw back together and it doesn't want to start. Any thoughts from the brain trust?

Things I've done in the recent past:

• Vacuum test - passed
• Pressure test - passed
• Compression test - passed
• New AV mounts (doesn't affect running, but nice to have since the old ones were rotted out)
• New bar, chain, sprocket, and clutch drum
• New carb kit (real kit, not aftermarket)
  • Set L and H one turn out as starting point.
  • Set idle 1-1/4 turns out as starting point.
• New air filter (Proline)
• Fuel filter looks fine. I think I replaced it a few years back
• Brand new gas (Stihl motomix)

I tried starting it and it wasn't catching. After a bunch of pulls (probably should have given up earlier), the lower half of the air filter was soaked in gas, some was puddled under the filter/carb, and there was a small puddle of gas inside the cylinder (1/4 tsp?). So gas is flowing. When I pulled the spark plug and put it against the cylinder, it showed a good spark.

Thoughts on what to check/try?

Thanks,
Tyler

 

[tomalophicon]

Are you certain your carb is put back together correctly? Have you pressure tested your carb?
i know you say there is good spark. Have you gapped your plug?

 

[OneStaple]

Are you certain your carb is put back together correctly? Have you pressure tested your carb?
i know you say there is good spark. Have you gapped your plug?

The spark plug gap is correct (I just verified). The plug isn't that old.

I'm fairly sure the carb was put back together correctly, but it's always possible that something went wrong. I'm fairly careful with such things and consulted the Tillotson manual for my carb to verify everything.

I have not pressure tested the carb. I guess that's next on my list of things to do.

Tyler

 

[tomalophicon]

The spark plug gap is correct (I just verified). The plug isn't that old.

I'm fairly sure the carb was put back together correctly, but it's always possible that something went wrong. I'm fairly careful with such things and consulted the Tillotson manual for my carb to verify everything.

I have not pressure tested the carb. I guess that's next on my list of things to do.

Tyler

You don't mention fuel and impulse lines either. I'd replace all of those as a matter of course.

 

[OneStaple]

You don't mention fuel and impulse lines either. I'd replace all of those as a matter of course.

Impulse line was replaced about 10 years ago and passed the recent vacuum/pressure testing. I think I replaced the fuel line at the same time, but am less confident on that. But wouldn't the fact that fuel is getting to the cylinder suggest that the fuel line isn't a problem?

Tyler

 

[OneStaple]

Carb passed the pressure test just fine.

Tyler

 

[Captain Bruce]

The spark plug gap is correct (I just verified). The plug isn't that old.

I'm fairly sure the carb was put back together correctly, but it's always possible that something went wrong. I'm fairly careful with such things and consulted the Tillotson manual for my carb to verify everything.

I have not pressure tested the carb. I guess that's next on my list of things to do.

Tyler

and? the spark tester shows you have spark???

 

[OneStaple]

and? the spark tester shows you have spark???

I don't have a spark tester, so I was only able to verify what looked like a good spark by placing the spark plug against the outside of the cylinder. Is it worth getting a spark tester for further testing/verification?

Tyler

 

[Vintage Engine Repairs]

Disconnect fuel line, take spark plug out, pin trigger and open choke. Pull hard 10-15 times.


Then put a teaspoon of fuel into the plug hole, screw spark plug back in and connect boot.

Turn saw on, pin trigger and ensure choke is still off. Pull hard and fast until it starts for a few seconds and dies. Confirm this before anything else.

 

[Captain Bruce]

I don't have a spark tester, so I was only able to verify what looked like a good spark by placing the spark plug against the outside of the cylinder. Is it worth getting a spark tester for further testing/verification?

Tyler

WELL! Thats a loaded question. If a guy has an ounce of wrench in him, he's got a tool box, and it sits on his workbench.

Yes, you should have a spark tester, compression gauge, leak-down tester, set(s) metric / S.A.E. of taps and dies, J-B Weld, and everything in between. Gasket paper is a must if the tank needs be split.

I have worked on Stihls all my life / yrs...and enjoy these old, 40 yr. old, saws alot. I re-conditioned an O31AVE last Spring. The customer wanted a like-new machine, as it was his Dad's. The paint is TCS Magic...and the white is Ford Gray. The Orange is Kobota

Lots of research into parts. The magnesium casings are prone to having bolts/screws, vibrate loose. That stripes out the threaded hole. Lots of thread repairs to be sure.

 

[Captain Bruce]

Disconnect fuel line, take spark plug out, pin trigger and open choke. Pull hard 10-15 times.


Then put a teaspoon of fuel into the plug hole, screw spark plug back in and connect boot.

Turn saw on, pin trigger and ensure choke is still off. Pull hard and fast until it starts for a few seconds and dies. Confirm this before anything else.

So, you don't have an air compressor? 10-15 times? to clear a flooded cylinder? let it sit for 5 mins., and swipe your wifes keyboard air guster.....My arm was sore reading this.

 

[Captain Bruce]

Before I got a pressure tester I used a cheap bike pump with a gauge. Worked well.

Worked well is subjective, not accurate.

 

[Vintage Engine Repairs]

So, you don't have an air compressor? 10-15 times? to clear a flooded cylinder? let it sit for 5 mins., and swipe your wifes keyboard air guster.....My arm was sore reading this.

Your arm gets sore pulling 10x without a plug / zero compression ?!

 

[Captain Bruce]

Ok, some of you convinced me to rebuild my 032 instead of selling for parts, especially since it ran well until I let it sit on a shelf with gas for a few years. It currently won't run, likely because of the carbs. And pulling the muffler shows some wear on the piston, but perhaps not enough to scrap it. There's a lot of carbon build-up around the muffler port too (see pictures, one at TDC, one in the middle, and one at BDC).

I'll be asking questions as I go, but here's some initial info.

• I got this saw used about ten years ago. I replaced the broken impulse line (which is why I got it cheap) and a couple things (filters, etc.) before pressing it into service. No full overhaul at that time.
• I think I replaced the intake boot back then, but it's been too long and I don't totally remember.
• Before this tear down, compression test says 165 psi (cold).

Things I plan to fix/replace/repair:

• Open up the piston/cylinder. Check for any additional damage to verify if this is worth the investment, and otherwise clean things up (carbon buildup, etc.) and put back together.
• New rings on the piston. This seems like a smart move once I have things open.
• Do a carb kit.
• New crank seals?
• Gaskets at all applicable locations.
• New AV mounts. They're all toast
• Clean fuel and air filters. Replace if necessary. Do they make a better air filter for this saw?
• Fix stripped threads, replace missing bolts.
• Hope everything works, tune it, and go have fun with it.

Let me know if there are other things I should be doing/checking

Tyler

Tyler: My apologies for not starting at the beginning of your thread......I've made so many comments based on a current comment...

anyway, the photos show the piston, rings, and cylinder. ALL are junk. The burnished marks on the piston skirts are the last bit of raw/lean fuel past, before it seized. The rings clearly show as "welded/melted" into the lands. IF the won't move, they are fried. There is plenty of scoring on the piston face, and cylinder. This saw will be a work of art once completely restored, including a NEW OEM engine......Send Photos!

 

[Captain Bruce]

Your arm gets sore pulling 10x without a plug / zero compression ?!

NO, of course not....its that whole exercise that I was scratching my head at........blow out the cylinder, and try a different, new plug....

if it still floods, there is an ignition issue......and Miller time. So simple.