Advice to run, unexpected Mahle cylinder piston o38

[GDS]

Piston has a blemish but not so bad I think, jug transfers are ported matched with waving beveled piston. Realize parts are cheap but curious about this pairing. Should I just swap out and let saw find a new normal. Hasn’t run in a very long time. Don’t know why saw was used as door stop.

 

[Vintage Engine Repairs]

Hard to see the extent of the damage from those photos, but often you can save cylinders. Stihl don’t use Mahle any more and from what I have read, they’re excellent. Go slowly and carefully if you use acid or alternatively you can use abrasives for a safer route.

Once you’ve established the condition of the cylinder, although not ideal, you can use feeler gauges if you don’t have a dial bore or snap gauges and measure the clearance between skirt and cylinder - post it here and I’ll get some specs about it being good to run or not.

Don’t use sandpaper or any other coated abrasive on the piston. Only use a file on the high spots, very gently.

Edit: one more note about acid - I have used it a few times and it has its place, but this image has stuck in my mind since seeing it - it got under the plating and destroyed the cylinder. Image courtesy of Tinman Saws from YouTube. If you pay close attention and use small amounts very carefully you’ll likely be fine, but worth keeping this in your minds eye when dealing with muriatic acid!

 

[spuldup]

That image makes my stomach turn!

 

[SteveSr]

Piston has a blemish but not so bad I think, jug transfers are ported matched with waving beveled piston. Realize parts are cheap but curious about this pairing. Should I just swap out and let saw find a new normal. Hasn’t run in a very long time. Don’t know why saw was used as door stop.

The reason that this saw became a doorstop is because the IDIOT that tried porting it didn't have a clue. Throw that top end away and start over with OEM.

 

[Mad Professor]

Hard to see the extent of the damage from those photos, but often you can save cylinders. Stihl don’t use Mahle any more and from what I have read, they’re excellent. Go slowly and carefully if you use acid or alternatively you can use abrasives for a safer route.

Once you’ve established the condition of the cylinder, although not ideal, you can use feeler gauges if you don’t have a dial bore or snap gauges and measure the clearance between skirt and cylinder - post it here and I’ll get some specs about it being good to run or not.

Don’t use sandpaper or any other coated abrasive on the piston. Only use a file on the high spots, very gently.

Edit: one more note about acid - I have used it a few times and it has its place, but this image has stuck in my mind since seeing it - it got under the plating and destroyed the cylinder. Image courtesy of Tinman Saws from YouTube. If you pay close attention and use small amounts very carefully you’ll likely be fine, but worth keeping this in your minds eye when dealing with muriatic acid!

View attachment 1131945

Acid won't do that to plating unless it's already compromised with holes, or someone honing with 50 grit.......

 

[ballisticdoughnut]

Replace piston and cylinder. Someone trashed the original which is a shame. OEM top ends are hard to find and expensive for the 038’s these days.

 

[NSEric]

That cylinder will never run good, it's toast.
The finger ports arent done right at all, the one on the exhaust side is way to high.
If you do them right finger ports work well in the older stihls with those style transfers. I have a big bore clone 066 with them but I only put them on the intake side of the transfer.

 

[GDS]

Yes will replace, have the saw up in running and use the old cylinder as a door stop.