Galled Piston Stihl 044

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It's spread over the workbench. Cylinder/piston and fuel tank were off before first post. All that's left is removing the clutch and flywheel, then a good bath. Does the case gasket also seal the bar oil tank? If that's the case I may split the case. It leaked bar oil sitting on its side, caps up. Know more once the flywheels off.
Don't worry about the oil. It likely came from the bar oiler outlet and/or the tank vent. You definitely want to do a vac/pressure test of the case and cylinder assembly after you have the jug mounted.
 
Thanks for the links. Found the operators manual for the 044 on line, would like to locate a shop manual too. If nothing else, a list of clearances and torque specs.

Don't intend to use the old cylinder so it will become a vacuum/pressure test block-off "plate" once the port openings are sealed.
 
Thanks for the links. Found the operators manual for the 044 on line, would like to locate a shop manual too. If nothing else, a list of clearances and torque specs.

Don't intend to use the old cylinder so it will become a vacuum/pressure test block-off "plate" once the port openings are sealed.
That's a good use for a fubar-ed jug. That said, the base gasket is a possible leak source so you may want to test after installation of the new bits.

In the meantime, check your Inbox for manuals.
 
It will be easier to remove clutch/flywheel with P/C back on and using a piston stop or a rope in sparkplug hole.

Clutch is lefthand thread, a $10 flywheel puller will fit many stihl saws.

New OEM P/C clearance is about 0.002" at the skirt. The pistons have ~ 0.005" taper top to bottom.

I'd try to clean up the OEM cylinder, the plating is really tough and it usually just piston smear/aluminum you need to clean up. Read up on this here.

Post some pictures of cylinder.
 
atpchas - Of course I dumped what you sent before opening thinking it was only a notification. Thank you for sending but... could I get you to resend, please?

MP - No obvious stuck aluminum, some pretty good grooves though. It still had compression so I suspect the saw was run for quite some time burnishing the damage. I'll run a dial bore gauge through it before spending any money. I have a fair amount of experience with Nikasil, you're right it is tough. Is that piston to wall clearance measuring the piston at the pin cl, tail of the skirt or somewhere in between?

First casualty of inexperience; clutch "basket", the part that unscrews. Haven't figured out exactly what I did wrong. No big deal to break it loose, but as soon as it turned it fell to pieces. All three spokes broke away from the center and the outer ring.
 
atpchas - Of course I dumped what you sent before opening thinking it was only a notification. Thank you for sending but... could I get you to resend, please?

MP - No obvious stuck aluminum, some pretty good grooves though. It still had compression so I suspect the saw was run for quite some time burnishing the damage. I'll run a dial bore gauge through it before spending any money. I have a fair amount of experience with Nikasil, you're right it is tough. Is that piston to wall clearance measuring the piston at the pin cl, tail of the skirt or somewhere in between?

First casualty of inexperience; clutch "basket", the part that unscrews. Haven't figured out exactly what I did wrong. No big deal to break it loose, but as soon as it turned it fell to pieces. All three spokes broke away from the center and the outer ring.


Bottom of skirt to cyl.

Usually don't get grooves unless something hard was bouncing around inside. Put a little muriatic acid on the "grooves" with a q-tip, it it bubbles up it's aluminum, or a groove through the plating.

Post some pictures of piston/cylinder.
 
First casualty of inexperience; clutch "basket", the part that unscrews. Haven't figured out exactly what I did wrong. No big deal to break it loose, but as soon as it turned it fell to pieces. All three spokes broke away from the center and the outer ring.

This happened to me recently. It was a real tough one to break loose and I went at it upping the torque of the impact driver. It finally gave, but the speed of the spinning because of the torque sent pieces flying. I was going to put it back together with new springs until I found half of one of the shoes. New clutch installed. Take home message: start at low torque and work in short bursts so as not to start it spinning like a whirling dervish when it breaks loose.
 
atpchas - Thanks! Didn't have reader for them so the wife will handle opening and printing at her work today.

MP - That's what I thought. You must like carnage, two requests for pictures! Don't a own cell phone but I do have a 19 year old digital camera, hope they're legible.

The Tone - Exactly what I came up with, instant RPM, weights flew out into the case and wtf?

Scallywag - If I did it that easy way... then what good is this dial bore gauge... ;-p
 

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Been following your thread but didn`t jump in right away, your cylinder will clean up , just be careful around the port edges/lips. The 044 and MS440 has been my mainstay saw since 1989 and have been through and through dozens of them. Currently have 7 real good working ones and they are still my favorite 70 cc class saw. Good luck with your build, any questions will be answered by the members here.
 
I've seen much worse pistons. It looks to have run rich at least for a while and may be mostly carbon scores. I'd go in light (use hand fingers) with some 220 wet/dry and water/detergent just to see whats there on ex side for a start, and get carbon/oily residue off. Hard to tell if some marks may be gouges? Still may have had a lean event later on.

I like to use acid to remove aluminum transfer but you must be careful not to get any in port edges or anyplace that might have small gouge/hole in plating. Alternate that with finer grades of paper. Wear gloves/goggles and have baking soda solution for mistakes or spills.

For clutches I use a breaker bar and piston stop (rope).

Stihl is proud of their parts, New OEM piston is ~$90, Meteor 1/2 that. Same idea W P/C assys. A Stihl gasket set will also have seals.

Feeler gauge method will get you~ +/- 0.0005-0.001" for clearance. Not as accurate as mics/bore gauge but will tell you if worn out.
 
Thanks to atpchas I have a parts list. Going with Meteor for either the piston kit or P/C kit. But the other stuff, mainly the carb and chain oiler hoses, filters, etc... I'm thinking of going with one of Amazon's mid range $$ rubber parts kits by Coolwind. I'd like to think paying a bit more than the cheapest available means a better product but it is likely that 90% of what's on Amazon is the exact same stuff repackaged and rebadged.

The crank seals are coming from my Stihl dealer and so is the replacement for the clutch carrier I broke and a shoe retainer. The flywheel has proven stubborn, the dealer offered to remove it n/c.
 
Thanks to atpchas I have a parts list. Going with Meteor for either the piston kit or P/C kit. But the other stuff, mainly the carb and chain oiler hoses, filters, etc... I'm thinking of going with one of Amazon's mid range $$ rubber parts kits by Coolwind. I'd like to think paying a bit more than the cheapest available means a better product but it is likely that 90% of what's on Amazon is the exact same stuff repackaged and rebadged.

The crank seals are coming from my Stihl dealer and so is the replacement for the clutch carrier I broke and a shoe retainer. The flywheel has proven stubborn, the dealer offered to remove it n/c.


Stihl gasket set comes with seals $21, seals alone $26
 
That jug looks like it might be salvageable. Theres a spot dead center above the ex port that looks questionable, but it's out of focus and could just be dust. Get your gasket and seal set together from the dealer. Intake and rubber lines too. It's worth it on a ~$400 saw.
 
That jug looks like it might be salvageable. Theres a spot dead center above the ex port that looks questionable, but it's out of focus and could just be dust. Get your gasket and seal set together from the dealer. Intake and rubber lines too. It's worth it on a ~$400 saw.

I would not be happy with putting $$$ into a saw and having a failure due to cheap AM rubber/carb parts, especially if they get run with corn fuel/gasahol. AV buffers might be an exception.

Let's see what cylinder looks like with a little clean up?
 
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