Stihl 038 Magnum

[Brian Y]

Hello,
I have been fortunate enough to buy a good-looking Stihl 038 Magnum. Sad to say, though that some years ago the owner put the dirty saw in his shed and left it. So, the steel parts have rusted and seized.

I’ve removed the clutch so that only the crankshaft stub remains on one side of the saw. On the other side the flywheel remains for now. I’ve also removed the muffler

After soaking the bore with diesel, I can rotate the crankshaft freely. However, intermittingly something sticks/strikes and stops the rotation. Looking through the exhaust port, it feels like the piston rings catch below that port.(Always in the same position).

I haven’t come across this problem before. Any thought please before I remove the cylinder.
Many thanks

 

[Mad Professor]

Hello,
I have been fortunate enough to buy a good-looking Stihl 038 Magnum. Sad to say, though that some years ago the owner put the dirty saw in his shed and left it. So, the steel parts have rusted and seized.

I’ve removed the clutch so that only the crankshaft stub remains on one side of the saw. On the other side the flywheel remains for now. I’ve also removed the muffler

After soaking the bore with diesel, I can rotate the crankshaft freely. However, intermittingly something sticks/strikes and stops the rotation. Looking through the exhaust port, it feels like the piston rings catch below that port.(Always in the same position).

I haven’t come across this problem before. Any thought please before I remove the cylinder.
Many thanks

Welcome to AS. 038 are one of my favorite saws

Better to put this in chainsaw forum for best responses.

You may need to take flywheel off for various reasons, do that before removing cylinder, best w/puller.

What does piston/cyl/rings look like through ex port, pictures will help. Any scores or gouges ? Is the cover off on flywheel side? And is it free of obstructions?

How solid is the obstruction? Turning flywheel by hand, can you make a full turn, or does it lock solid? One thing that won't stop rotation but you can feel turning the saw is the flywheel magnets passing by the coil. This will just be some resistance, nothing to worry about

If it's solid the saw may have a broken ring, one of the bearings let loose, or it "ate" something through intake side.

 

[mehmetk]

Welcome to AS. 038 are one of my favorite saws

Better to put this in chainsaw forum for best responses.

You may need to take flywheel off for various reasons, do that before removing cylinder, best w/puller.

What does piston/cyl/rings look like through ex port, pictures will help. Any scores or gouges ? Is the cover off on flywheel side? And is it free of obstructions?

How solid is the obstruction? Turning flywheel by hand, can you make a full turn, or does it lock solid? One thing that won't stop rotation but you can feel turning the saw is the flywheel magnets passing by the coil. This will just be some resistance, nothing to worry about

If it's solid the saw may have a broken ring, one of the bearings let loose, or it "ate" something through intake side.

I agree. With a few pieces of equipment and a solid sharpening, it can be used for a long time after the problem is solved. In my opinion, it is necessary to dwell on this beautiful product. I'll do the same for my other model vehicle. @Brian Y Good luck my friend.

 

[MacAttack]

Hello, you'll get a lot more responses and help by sharing some pictures of the saw, exhaust port, etc

 

[Jack Clancy]

Welcome to AS. 038 are one of my favorite saws

Better to put this in chainsaw forum for best responses.

You may need to take flywheel off for various reasons, do that before removing cylinder, best w/puller.

What does piston/cyl/rings look like through ex port, pictures will help. Any scores or gouges ? Is the cover off on flywheel side? And is it free of obstructions?

How solid is the obstruction? Turning flywheel by hand, can you make a full turn, or does it lock solid? One thing that won't stop rotation but you can feel turning the saw is the flywheel magnets passing by the coil. This will just be some resistance, nothing to worry about

If it's solid the saw may have a broken ring, one of the bearings let loose, or it "ate" something through intake side.

Good thinking! I also would not dismiss broken bearing assembly...

 

[Jack Clancy]

Hello,
I have been fortunate enough to buy a good-looking Stihl 038 Magnum. Sad to say, though that some years ago the owner put the dirty saw in his shed and left it. So, the steel parts have rusted and seized.

I’ve removed the clutch so that only the crankshaft stub remains on one side of the saw. On the other side the flywheel remains for now. I’ve also removed the muffler

After soaking the bore with diesel, I can rotate the crankshaft freely. However, intermittingly something sticks/strikes and stops the rotation. Looking through the exhaust port, it feels like the piston rings catch below that port.(Always in the same position).

I haven’t come across this problem before. Any thought please before I remove the cylinder.
Many thanks

I wrote a longe answer ....forgot to mentio that if the piston was stuck in the bore and you used diesel to free it......you may have a stuck ring..passing compression. Did you (also) drain the crank after the diesel job?

 

[sbc350]

If its that bad honestly If your keeping it pull jug and inspect make a executive decision to replace or not but just change bearings and seals anyways well worth spending a few dollars to go the extra mile but ... make sure to check the crank bearing too if pulling apart before ordering a topend if you has to go that route