Freeing up a Seized Stihl 070

[Sawcanuck]

I have read and learned a lot on here and thought I would take a little time to share what I tried/learned trying to unseize this Stihl 070 saw I bought it as a parts saw. It was locked solid and looked like it had sat a long time. It had some physical damage (to the top covers and clutch cover so I was hoping it was in running condition at the time that it got dropped/run over. I was hoping to free it up and see if I had a usable piston and/or cylinder.

I first removed the covers and tried to get it to move by putting a wrench on the flywheel nut. Stuck solid.
I then tried adding several different penetrating fluids etc down the spark plug hole. I wasn't in a rush so I would pour it in and let it sit for a few days and try the wrench on the flywheel nut. I would then dump it out and try the next one. I tried fuel/oil mix, diesel, Deep Creep, Marvel Mystery Oil, PB Blaster. Wouldn't budge. With every other saw I have tried to free up I had always had success by this point. I put a lot of pressure on the flywheel nut but I was worried about stripping/damaging the crankshaft threads (I wanted the crankshaft for another saw). I tried heating up the cylinder with a propane torch and tapping on a wood dowel in the spark plug hole to try to break the piston/rings free. Wouldn't budge.

I removed the cylinder bolts to see if I would get any rotation from the crankshaft. I did and I was happy that the crank/bearings were free. Tried tapping on a wood dowel again while suspending the cylinder. Nothing.

The piston was up pretty high in the cylinder. I read about making a fitting to pump grease into the cylinder to force the piston down. I made this...



It worked great. The hydraulic pressure pushed the piston down until it got to the ports and the grease escaped. But it was a start and I figured it would keep coming the rest of the way...it didn't.

To be continued...

 

[Sawcanuck]

I thought about using the same fitting pictured with a slide hammer to pull the cylinder from the spark plug hole but I was worried about damaging the spark plug threads.

I wanted to come up with a "pusher" to try to push the cylinder up from the case. I walked around the hardware store for a while and came up with this...



1/4 inch threaded rod (no metric rod available near me). I was worried about damaging either the base of the cylinder or the mounting surface on the case. I found these free spinning washered nuts. I locked them to one end of the threaded rod with a lock washer and a nut so the threaded rod would not make contact with the case and the whole assembly would spin without causing damage.



I then used a flat washer against the cylinder base to prevent damage. I added a couple of nuts tightened together on the top of the threaded rod to give me something to put a wrench on to turn the rod.

 

[Sawcanuck]

The whole assembly looked like this...


I put an open wrench on the nut under the cylinder and slowly cranked on the rod from the top, alternating from one to the next.

 

[Sawcanuck]

This worked fantastic. Cylinder slid off with very little pressure. Piston was a bit scuffed but cylinder was in great shape (once I cleaned all of the grease, etc out of it).



I took some pics as I did this and figured I would share in hopes it will help someone out at some point.

Those nuts with spinning washers worked great and there was no damage to the case or cylinder base. I also left the base gasket in place for extra protection.

 

[Deleted member 149229]

I would say you win the “McGyver” award. Innovative thinking.

 

[usmcbuckwild]

Ingenuity at its best! I guarantee this will be utilized by others. Good job

 

[056 super p26 2054 turbo]

Good idea as long as the base is thick enough if not could make a steel plate to spread pressure out. I've got a pioneer 450 that is stuck pretty bad I may have to try this on. Also have an 07 that and the 450 would be a mean pair of top handle saws lol

 

[Sawcanuck]

I would say you win the “McGyver” award. Innovative thinking.

I used to love that show!

 

[Sawcanuck]

Ingenuity at its best! I guarantee this will be utilized by others. Good job

I have learned so much from reading this forum. I figure it's about time I contributed something useful lol!

 

[burnses]

nice clever save!

 

[Sawcanuck]

Good idea as long as the base is thick enough if not could make a steel plate to spread pressure out. I've got a pioneer 450 that is stuck pretty bad I may have to try this on. Also have an 07 that and the 450 would be a mean pair of top handle saws lol

Gotta love the odd looking old top handle saws...I have always liked the 07.